Gunsmithing Any thoughts on structured barrels?

[ohiofarmer]

@sirhrmechanic Perhaps I’m being dense, but what are you describing regarding the recoil lug install? Is there a secondary recoil lug hidden from view on the underside of the barrel?

 

[sirhrmechanic]

Barrel button from the blank...

If you ever want something to do with your 'saved' buttons (and you DO save them, right?)

They make great case pulls...

TacOps finest!

Cheers,

Sirhr

 

[sirhrmechanic]

@sirhrmechanic Perhaps I’m being dense, but what are you describing regarding the recoil lug install? Is there a secondary recoil lug hidden from view on the underside of the barrel?

Cheers,

Sirhr

 

[ohiofarmer]

View attachment 7839954


Cheers,

Sirhr

Yes, that’s a recoil lug. I guess I didn’t understand your “We installed a recoil lug on the barrel at John Mills suggestion.” Is something different normally done on the structured barrels?

 

[Nik H]

Barrel button from the blank...

If you ever want something to do with your 'saved' buttons (and you DO save them, right?)

They make great case pulls...

View attachment 7839936View attachment 7839937

TacOps finest!

Cheers,

Sirhr

What was the contour profile or the OD of the blank if it is a straight contour?

 

[John Baker]

I still have to get some photos... but with this now in hand and having had a day to spend fondling -- er -- evaluating it in the most scientific and professional ways possible... some impressions. And probably have a window to shoot it this weekend, but not to any kind of potential. So that will have to wait for mud season to end.

First, it was a long process but totally worth it! For those who do not know, it's a M700 .300 Winchester Magnum action/bolt face. Bought the action from, I think, @powdahound76 here on SH a year or so ago for... whatever project cropped up. I chose .300 Win Mag because it would work with this action and because I have another superbly-accurate .300 Win Mag in my Mk 13. They are good to compares side-by-side. And I know I have great ammo loaded as well. So as this was as much to really get a feel for a structured barrel as anything, this is the reason I chose a cartridge that is really not going to see the full-potential of a structured barrel compared to some of the big ELR calibers.

The chassis is a KRG Whiskey 3 (@Massoud) and is my second chassis from them. My first being a very early Bravo. And I got to play with a prototype TRG stock from them in about 2012... so have a long history of loving everything the KRG folks put out. Big fan of the mag release button for some reason ;-) Anyway, there was some concern about the barrel channel being large enough for the OD of the structured barrel. No worries, it fits with plenty of room to clear!

Final assembly was supposed to be done by Vestals. But by the time the barrel was done, they were backed up something like 9 months and my 'slot' was gone. Which ended up being a good thing because @John Baker and the folks at TACOM up with John MIlls at Buffalo Creek Precision in Bellingham, Wa. https://www.buffalocreekprecision.com/ John Mills is another ELR builder who is making a name for himself and this is his first structured barrel project and won't be his last for sure. He was an absolute pleasure to work with on this project. In fact, we ended up having several very indepth conversations about gain twist, chambers, harmonics and a wide array of gun topics. He is so sold on the structured barrel idea that I think he is ordering one for himself at this point. He was reasonably priced, great at communications, did the work in a timely manner and was overall everything one could want in a builder. I am already looking for our 'next' project to work on.

Rifle is done in a gain twist. I will share the @Frank Green Bartelin barrel "Button" cut off the end of the barrel when I post some pictures. Worth the wait! The reamer used for the chamber was a .339 NK. John Mills suggested it and I have no issue with his recommendation though may have to do some neck turning. It chambered my 'fireforming' rounds fine.

We installed a recoil lug on the barrel at John Mills suggestion. And it has a brake that will hold a suppressor fitted to it. With suppressor, I may need guy wires to support it. It will look like Anzio Annie.

An older Sphur mount and one of my Signature USO 3.2-22 (or something like) that EREK Mil scopes for optics.

The fit and finish on the barrel is gorgeous! It has several small 'steps' along its length. I am not sure if those were put in at TACOM, but assume they were. The cooling 'dimples' add surface area over the chamber and are beautifully done. I have not figured out the purpose of the holes into the 'structured' drilling holes. Either for air circulation or perhaps to prevent the air inside from acting like a hammer or a spring when the gun is fired. I could see a desire to let air flow through the drillings, not sit static inside. That's a question for John Baker, I guess!

As I have not fired it yet, but I will quote John Mills from his range trip where it shot extremely well with nothing more than fireforming ammo I sent him: "I will say the recoil was very interesting and I was able to see impacts at 100yds which was really pretty amazing." He also mentioned that the think is a "Lookie-Lou" magnet at the range. Lots of "What is that." Here is one of his targets. Again, keep in mind that this was fireforming ammo only. With 'leftover' lead soft nose hunting bullets and some Sierra's left over from another project... This ammo was thrown into the cases for function testing, not match quality. Overall, no issues with the 'test' group!

View attachment 7839826

Only other thing we are running into is some feeding from the mags and I need to order a mag lip adjusting tool. 4th round was diving until a slight lip modification was made. After that, the mags fed fine.

So when the weather gets to not suck.... I'll take this and the Mk 13 out for a side-by-side comparison. And I expect that the structured barrel is going to be really great to shoot. And with proper handloading is going to shoot absolute holes in holes.

Overall, a worthy and fun journey and one that has not stopped by any means. Already working on getting a structured .300 NM barrel done for "Boomer" the MRAD. And possibly another ELR project that is cooking away on my back burner. Both should have some serious ELR potential to them.

Thanks to everyone, especially the folks at TACOM who showed up here to explain their product... and I hope are gaining some serious converts to a cool technology!

Cheers,

Sirhr

To answer some of the basics:
Blanks all start as straight blanks: 1.5, 1.75 and 2.0 inch are the most common.
We use every bodies blanks as long as they meet the initial basic criteria.
Any gunsmith can chamber these barrels as long as their lathe takes the diameters and lengths.
OD's presently go from 1.210 to 2.10"dia. Sub 6lbs to 19lbs.
Like all "engineering", compromises are present. Running to an existing chassis will pull our barrels out of their sweet spot but weight for weight will be superior in multiple aspects. Certain geometries allow maximum cooling with maximum resistance to bending/whip. An optimum barrel is 1.77"Dia at 32" weighs 10.2lbs- within one pound of most F class and PRS barrels. Producing 1.25"D barrels create a barrel approximately 2lb lighter than the typical heavy barrel.
They will run cooler for much longer strings, less group drift, less SD drift.
Very lenient on powder ladder tests and bullet weights.
Longer life... cooler running typically equals longer life.
Bolt or gas gun capable.

The holes- yes they are vents that are quite active during a shooting cycle. Brake designs are available to maximize the flow of air thru the barrel (up to 25m/sec) and have been known to create little piles of sand/debris on the backside of the brake while shooting (Mark & Sam After Work).

This barrel is smooth - normally we supply the barrel with a threaded pattern- alternating left and right hand- to increase the surface area and cooling effect, further interrupt the vibration event, and to reduce the silhouette of the barrel by introducing a Moire' fringe event, both to the eye and to electronic detection.

We cryo most barrels- my first hand experience with cryo says it absolutely stress relieves material and adds a "toughness" to the system.

The dimples- interrupt the wave events.

We ran a new 6.5CM this past week: three factory ammos and one hand load (from previous gun). Four total ammo types- two target match type and two hunting styles. We shot a Hornady 142gr round at 2710 and a 143grNosler Accubond at 2940fps. Both printed 1/2moa groups stacked vertically with essentially sub 1/4moa left or right change. However, all three factory rounds 129gr to 142gr all shot sub 3/4moa- including the clean cold bore round. Multiple 3rd parties confirm this type of performance.

I look forward to the paper results... I think I might know what they are...

 

[6.5SH]

@John Baker Can you explain more on "Running to an existing chassis will pull our barrels out of their sweet spot" ?
Are these preferred to be used with a specific action and chassis?

 

[John Baker]

It would be kind of like comparing an airplane wing that weighs two tons: One wing is a solid flat bar the other designed shapes/bulkheads/spars. Or a radiator who's core weighs 5lbs: a solid 5lb block or a finned unit.
Our base design looks for the optimum cooling surface with the maximum OD that can be obtained. The two line up pretty good using the current design. Multiple design structures are occurring within the barrel- each bringing a positive/negative to strength vs cooling. Therefore if we reduce the OD to fit a channel we decrease the ability to resist a bending moment and reduce the surface are presented to the atmosphere. Current chassis and stocks have settled in on the 1.25 channel (due to weight restrictions?) but that value is well below our optimum value. Shooters have noted (F class) that our barrel that weighs 24% less equaled the performance of the heavier barrels (Mark and Sam noted the same) - but also had superior cold bore shot capability. It might take a bit before someone is willing to shoot a 1.75" barrel...
We can easily shoot a 20shot string on our 300Norma, 6.5CM approaches 50rds before drift sets in, data compensation on large calibers is 2x rounds fired with a normal barrel typically.
Concerning actions: no particulars.
Chassis: a primary question when a barrel is ordered is the barrel channel requirements. We have cut a few chassis for sure.... Scott McRee produces fore ends specifically to clear the big barrels.

 

[sirhrmechanic]

^^^ This is why this whole project started.

Because gain twist, structured barrels... are among the technologies that will take ELR well into the future.

All you all should start reading this thread from the beginning. This is stuff that has been proved out in artillery and large-scale guns for decades... now taken down to small arms and MORE importantly.... affordability in small arms.

Why I've been on this bandwagon since the first post. And why this kind of tech is going to be game-changing for the precision marksmanship game.

But more to come. Much more. Structured barrels are just one part of the equation and I will bet dollars to donuts that in just a few years, there are a lot of converts to structured barrels... gain twist and a LOT more being discussed/debuted here on SH. @lowlight has some podcasts that are just starting to scratch the surface of what's to come.

Cheers,

Sirhr

 

[camocorvette]

@sirhrmechanic Perhaps I’m being dense, but what are you describing regarding the recoil lug install? Is there a secondary recoil lug hidden from view on the underside of the barrel?

I think this is what you were wondering about.

 

[camocorvette]

I just stumbled on this. At first I was like wtf??
Then I read and read some more.

Fuck I live under a rock...
Gorgeous rifle @sirhrmechanic.

 

[Leftie]

This is an extremely interesting thread, and I am glad that I took the time to read up to this point, as I had heard about these barrels some time ago, but couldn't find much information outside of what has been provided by the company.

Eagerly following what's going on here, as the science behind what you all are doing here is fascinating, and it appears from what I've read and seen that there are very tangible benefits to the shooter from these barrels.

Looking forward to seeing how this progresses.

 

[ohiofarmer]

View attachment 7840306

I think this is what you were wondering about.

No, I know what a pinned recoil lug is. His “We installed a recoil lug on the barrel at John Mills suggestion,” is what made me think there was something different. Apparently not.

 

[sirhrmechanic]

No, I know what a pinned recoil lug is. His “We installed a recoil lug on the barrel at John Mills suggestion,” is what made me think there was something different. Apparently not.

Yes, I should have said Action or "Between action and barrel." My bad.

Cheers,

Sirhr

 

[ohiofarmer]

Yes, I should have said Action or "Between action and barrel." My bad.

Cheers,

Sirhr

No worries. Thanks for clarifying. Not having a structured barrel, I wasn’t sure if they do something different on that front. Because they sure seem to do a lot, “differently,“ from the old norms! I look forward to hearing how it works out for you.

 

[NamibHunter]

This is an extremely interesting thread, and I am glad that I took the time to read up to this point, as I had heard about these barrels some time ago, but couldn't find much information outside of what has been provided by the company.

Eagerly following what's going on here, as the science behind what you all are doing here is fascinating, and it appears from what I've read and seen that there are very tangible benefits to the shooter from these barrels.

Looking forward to seeing how this progresses.

Good point.

Would be fascinating to see if a ladder test confirms that positive compensation does not happen with structured barrels. Faster shot always impacts higher, for all powder loads. It means no ugly 2” scatter nodes where the opposite of positive compensation occurs. Should shoot almost any good quality ammo into groups well below 1” at 100. Is a seating depth optimization even needed?

 

[kthomas]

Good point.

Would be fascinating to see if a ladder test confirms that positive compensation does not happen with structured barrels. Faster shot always impacts higher, for all powder loads. It means no ugly 2” scatter nodes where the opposite of positive compensation occurs. Should shoot almost any good quality ammo into groups well below 1” at 100. Is a seating depth optimization even needed?

And no more need for tuners

 

[John Baker]

Tuners could still have their place- though for potentially enhanced additional attributes not normally associated with them. You can see a ladder test by Coastal Precision from a few years back. We have found the barrels to be nearly unresponsive to moving brakes up and down the threads- close enough at 200yds that you better be on your game to pull the differences. We consistently shoot with our MagnetoSpeeds on the barrels as they really have no impact on the group. We do move the bullet up and down the land to help control pressure at the bolt. We shot a 33xc a few years back at a 1000yds. A 7" group was shot with .025" to .150" of bullet offset, three shots per setting. We quickly bounced to the .150' off of the land as the group was not responding. However, one test and 12 bullets don't mean a lot. But I do know we shoot clover leaves with bullets ranging from (300Norma or WM) 168 at 2200fps to 3400fps to 230's running 3000. I can really say that within reason- a good bullet loaded to a good concentric value... will shoot.
Our next generation of barrels will be nearly 3x stiffer (plus potentially a much greater heat/wear resistance) with a goal to significantly reduce the "barrel vibration" with further features applied to the barrel concept. At that point I don't believe a tuner will help unless it weighs 10lbs... just kidding there...

 

[NamibHunter]

Tuners could still have their place- though for potentially enhanced additional attributes not normally associated with them. You can see a ladder test by Coastal Precision from a few years back. We have found the barrels to be nearly unresponsive to moving brakes up and down the threads- close enough at 200yds that you better be on your game to pull the differences. We consistently shoot with our MagnetoSpeeds on the barrels as they really have no impact on the group. We do move the bullet up and down the land to help control pressure at the bolt. We shot a 33xc a few years back at a 1000yds. A 7" group was shot with .025" to .150" of bullet offset, three shots per setting. We quickly bounced to the .150' off of the land as the group was not responding. However, one test and 12 bullets don't mean a lot. But I do know we shoot clover leaves with bullets ranging from (300Norma or WM) 168 at 2200fps to 3400fps to 230's running 3000. I can really say that within reason- a good bullet loaded to a good concentric value... will shoot.
Our next generation of barrels will be nearly 3x stiffer (plus potentially a much greater heat/wear resistance) with a goal to significantly reduce the "barrel vibration" with further features applied to the barrel concept. At that point I don't believe a tuner will help unless it weighs 10lbs... just kidding there...

John B, this would imply that load development is much shorter/simpler/quicker and burning perhaps significantly less components in the process?

I realize a large ES at distance will create vertical, but other than looking for max pressure, then finding lowest available ES/SD working down from the max pressure charge, what else needs to be done to complete load development?

Do you really have to test 5 different bullets and 3 different powders… to find one “that your rifle likes”? Or do they all shoot (almost) equally well.

“We do move the bullet up and down the lands to help control pressure at the bolt”:

OK, so jump has limited effect on group size, but a shorter jump (or especially a jam) will increase peak pressure and therefore speed. A hard jam could spike the pressure over a 100 fps in some cases, so there certainly is a strong effect there to play with. So yes i can see how seating depth becomes a tuning variable that leaves group size intact (structured barrels do not whip and therefore do not benefit from or suffer from positive/negative compensation), but seating depth/COAL still moves speed and pressure up or down to stay close to max…. Perhaps to compensate for temp sensitivity of your primers, more so than powders. [We have “Extreme” powders like H4350 that are far more temp stable than before, but no temp stable primers yet…]

Do you now use COAL as a tuning variable to deal with the temp sensitivity of the powder/primer combo, load a slightly longer jump for summer and a smaller jump for winter, or even a mild jam for mid-winter in the deep snow? To avoid over pressure situations only, or do you try to keep the speed the same as before? Do you still see flat spots/nodes in the powder vs speed diagram…. To help minimize your SD.

Sorry, million questions… but you see where i am going with this…

 

[TriggerJerk!]

This is why SH is so important. Our membership includes a huge amount of scientific and engineering knowledge. It has allowed us to debate, hypothesize, and show test results for many questions surrounding the efficacy of structured barrels. I sincerely hope that readers appreciate the ability to watch ‘the status quo’ being challenged, in real time, over the course of this thread. Small, but forward steps, leading to some really cool changes that will impact precision shooting.

It could only happen here on SH!

 

[NamibHunter]

This is why SH is so important. Our membership includes a huge amount of scientific and engineering knowledge. It has allowed us to debate, hypothesize, and show test results for many questions surrounding the efficacy of structured barrels. I sincerely hope that readers appreciate the ability to watch ‘the status quo’ being challenged, in real time, over the course of this thread. Small, but forward steps, leading to some really cool changes that will impact precision shooting.

It could only happen here on SH!

Curious what the OP has seen so far in terms of the presence or absence of “nodes” (flat spots in the speed), lack of positive compensation, and the use of jump as a way to avoid overpressure - or perhaps as a way to maintain very good ES…

I am itching to order a structured barrel!

The video that John Baker is referring to:

 

[sirhrmechanic]

So Saturday, meeting up with @pmclaine and perhaps a couple of other SH guys to shoot the structured barrel...

Probably also the MRAD and my IDF Mauser and maybe even my .14 Eich and Whitworth Civil War sniper. It's going to be the first nice day of the year... and while we're only looking at 550 or so... it will let me fireform a lot of brass. And run some things through a first ringer.

Can't wait. Every single weekend here has SUCKED!!!

So getting down to the VT Border (Southern Banana belt) Saturday will be great!

Sirhr

 

[sirhrmechanic]

Curious what the OP has seen so far in terms of the presence or absence of “nodes” (flat spots in the speed), lack of positive compensation, and the use of jump as a way to avoid overpressure - or perhaps as a way yo maintain very good ES…

I am itching to order a structured barrel!

The video that John Baker is referring to:

Just order it... but if you are waiting for my feedback.... by all means, order it Monday.

I can't wait to shoot it. But I know from my past work in small arms development that you don't need my experience with this rifle build. Just order it.

Sirhr

 

[TriggerJerk!]

Curious what the OP has seen so far in terms of the presence or absence of “nodes” (flat spots in the speed), lack of positive compensation, and the use of jump as a way to avoid overpressure - or perhaps as a way yo maintain very good ES…

I am itching to order a structured barrel!

The video that John Baker is referring to:

I don’t have one yet, but my next barrel will likely be a structured gain twist barrel.

I am hoping that we see addition results in different calibers and barrel contours in the coming year. But so far it would appear that there is less barrel whip. As additional data becomes available, a cannonical correlation or cannonical discriminant analysis (i.e., CAP) would help to identify variables influencing results (e.g., cooling, stiffness, dampening, or proxy metrics like barrel life, radial dispersion, harmonics, etc.), and therefore allow for more focused testing.

Seems really interesting so far.

 

[akmike47]

Someone order one in .22lr for your NRL22 rig lol

 

[Leftie]

A somewehat controversial idea has been keeping my attention lately related to this thread:

I am extremely curious how a shorter length (11.5-18") structured barrel performs by comparison to traditional barrels in the same length, especially with projectiles of the .224-.308 diameter flavor...

 

[sirhrmechanic]

So Finally.... the planets aligned. The weather cooperated. Thanks to @pmclaine had a beautiful pasture to set up to 550 unknown... it was a great day to fire the structured barrel.

First, however... We humped posts, steel targets, hit lamps, hangers, etc. out to 550 yards or so. I calculated the distance we walked up and down the pasture with gun bags, scopes, mats, ammo cans, packs, steel, posts... we did some 4 miles of 'loaded marching' before we could even begin to shoot. But immediately sighted in my .14 Eichelberger. New/old USO 10x scope on it. Got it on paper and then driving tacks. And then helped some of Pmclaine's friends with their rifles. Fixed a scope base. Got them shooting good groups. And generally helping out with some coaching.

So finally around noon got out the structured barrel. Refresher... Model 700 Magnum Bolt Face rifle poked and stroked by Fritz Alquist. KRG W3 chassis. .300 win Mag .339 NK chamber reamer in structured barrel. USO SN-3 Scope in a Sphur mount. Shooting prone off a mat. With bipod and a rear bag made from a sock filled with gutted out Beanie Babies. Some know that story. Anyway, pretty rustic setup. But it was a stable setup in what I call some perfect conditions. Light was great. Mirage was not huge... but helped read wind. Wind was up and down from calm to about 7 - 12 mph full value from right. But it was coming and going. So if you waited a few seconds, the wind was not a factor.

Ammo I will refer to as... junk. This plays into my impressions later. And it's not really 'junk' but it's not made for this rifle. Or to shoot seriously. It's part of about 400 rounds I made in 2019 for my Mk 13 Mod 0 ex Seal rifle. And they were only made for fireforming to that rifle. Nothing else. I don't remember the exact charge (I will post later) but I think it was RL 22. Boolits were something I bought cheap here on SH. Again just for fireforming. In 2019, I fireformed about 100 rounds for the Mk 13 and loaded some real tack-driver rounds for the Mk 13. And the rest sat in an ammo can. It's one of the reasons I picked that Cal for the Structured barrel. Because I know I have a track record loading for it. It's a good testbed.

So for the firing... I was pretty dialed in from earlier sighting in.

First few shots were confirming zero. Gunsmith had zero'd it using ammo I sent him. So it only took a couple of shots to confirm that it was right on at 50 where we had a target set up for fixing hunting rifles and for getting the MRAD and Eich. on paper.

First three shots were through the same hole. Not surprising at merely .50. But the group was tiny. Somewhat surprising for 'junk' ammo. but more on that later.

Fired a few more shots at a popper at about 75... then a square at 100. Then proceeded to simply whack steel with one round after another at 300 - 350. Then reached out to one of our 'far' targets. I'd miscalculated the 'drop' on the .300 WM at that range. So hit below the steel. But apparently the windage was dead nuts. Because I cut the T-post off a couple of inches below the steel and the whole target dropped like it was shot. It was pretty funny. But looking later at the T-post. The windage on the rifle had to be dead nuts, even if the boolit dropped more than I predicted (probably because fireform rounds were not 'hot.'.

Phil fired a few shots... and got the only picture of the day. And the landowners/locals got behind it and proceeded to not miss a thing... just whack steel out to about 350 - 400 like they were plinking .22's.

So this kind of confirms one of the first things that I've been 'reading' about the barrels is that they seem to be ammo-friendly. That said, it's hard to judge off one single load. Even if we did fire a bunch of them. If the rifle was doing this with my 'junk' fireforming ammo, I am going to be impressed as hell with ammo I tailor to this barrel/gun. ** But the conversation earlier in this thread about how the structured barrel is 'ammo friendly' and can digest lots of 'range' of loads would not surprise me. Again, until I start really working on ammo and ladder charges and the like, I won't know for sure.

The interesting thing was both the recoil and the 'feel' of shooting. The gunsmith who put it together commented that it was 'wierd watching my hits at 100 through the scope.' This was immediately apparent. This gun recoils like a .308. Not a .300 Win Mag. And the 'Feel/sound' of the shots is totally different. We all know that sharp crack/snap of a magnum. (or the "pinging" of an AR) when we hear/feel it. This was different. More of a 'hollow boom.' Like distant artillery. And the impulse was sort of a 'shove.' Not the kick of a .300 WM. (And BTW, I'd just fired a .300 Weatherby Mag from a pencil barrel Rem 700 hunting rifle a few minutes before. That smarted.) Even Pmclaine commented that it didn't feel like a Magnum (he can chime in). But like a .308.

I can't talk much about barrel heat. But it never got beyond warm. I grabbed the barrel after shooting. Warm. It was in 'some' sun out, but was overcast and only in the 60s. So I can't comment on cooling at this point. But don't doubt it cools well. Just didn't fire long strings to do any comparisons.

Next step is to load 'for' this barrel. And if yesterday is any indication, my initial instincts about this and my belief in TACOM are confirmed. And with spring 'really' coming to VT. I will be able to get some more brass fireformed and load up 100 rounds of tack driving ammo soon. And ammo that extracts better. Again, my bad not the gun's.

The only picture we got of the Structured barrel yesterday. Pmclaine holding it. I don't think he wanted to give it back.

Anyway, this is initial impressions. The biggest thing, I think, that I notice right off is the recoil impulse. I had read about it... and been told about it. But until you shoot it, you don't appreciate it. I definitely want to understand the physics better. I am assuming that the 'structure' of the barrel is absorbing recoil impulse? Maybe spreading the impulse into the structure rather than straight back? Enquiring minds want to know. But until you shoot it, it sounds like voodoo. Until you shoot it. Does 'recoil impulse' make the structured barrel game-changing? Alone, of course not. But what is happening I think does make it a gamechanger for the ELR game or some other critical roles. I just don't yet understand it all well enough yet. But we will. Whatever is going on, the first shooting was impressive. Moreso because of the ammo.

Thanks to John Baker and everyone who has contributed to this so far. It's a great journey that's just beginning. Thanks, esp. to Pmclaine for sharing his shooting honey hole and his company while everything up here is still a semi-frozen swamp. And, as always, thanks to SH for being the petri dish for all this cool stuff.

More to follow! But, yeah, this was a barrel worth waiting for. Can't wait to see what it'll do with some 'real' ammo!

Cheers,

Sirhr

* Edit. Load was FC case, once fired. Full length resized. CCI Magnum primer. 62.8 Gr. Reloader 22. 220gr HPBTM Sierra. COAL 3.325 No attempt made to seat out to lands. Again, made to fireform in my Mk 13. Not the Structured Barrel.


** A side note. I was having trouble with this ammo in my chamber. Some would not chamber, so I set it aside. I know it works in the Mk. 13. Some chambered fine. I chalk this up to necks that are not perfect and that I was fireforming only. Also some would not extract after firing. A 'touch' with a cleaning rod and they fell out. But the Rem extractor was just not quite grabbing on some of the fireforming cases. The cases that did work, I will be using to make proper ammo, up to and including neck turning.

 

[obx22]

Tuners could still have their place- though for potentially enhanced additional attributes not normally associated with them. You can see a ladder test by Coastal Precision from a few years back. We have found the barrels to be nearly unresponsive to moving brakes up and down the threads- close enough at 200yds that you better be on your game to pull the differences. We consistently shoot with our MagnetoSpeeds on the barrels as they really have no impact on the group. We do move the bullet up and down the land to help control pressure at the bolt. We shot a 33xc a few years back at a 1000yds. A 7" group was shot with .025" to .150" of bullet offset, three shots per setting. We quickly bounced to the .150' off of the land as the group was not responding. However, one test and 12 bullets don't mean a lot. But I do know we shoot clover leaves with bullets ranging from (300Norma or WM) 168 at 2200fps to 3400fps to 230's running 3000. I can really say that within reason- a good bullet loaded to a good concentric value... will shoot.
Our next generation of barrels will be nearly 3x stiffer (plus potentially a much greater heat/wear resistance) with a goal to significantly reduce the "barrel vibration" with further features applied to the barrel concept. At that point I don't believe a tuner will help unless it weighs 10lbs... just kidding there...

John Baker,
I’m just an old dummy rimfire nut, with an interest in extreme accuracy, which prompts a few questions:
Does this benefit rimfire accuracy at all given the low pressures and heat involved?
Have you folks produced a .22 rimfire sized bore, at what twist rate, and since the word “forgiving” has come up with regards to handloads, is such a barrel accurate with a broader range of ammo?
How is it substantially better than a barrel with straight deep flutes?
I follow the folks (online) who stretch the humble .22LR out beyond 1000 yards, and hope to do the same myself one day soon.
Take care,
warren

 

[John Baker]

John Baker,
I’m just an old dummy rimfire nut, with an interest in extreme accuracy, which prompts a few questions:
Does this benefit rimfire accuracy at all given the low pressures and heat involved?
Have you folks produced a .22 rimfire sized bore, at what twist rate, and since the word “forgiving” has come up with regards to handloads, is such a barrel accurate with a broader range of ammo?
How is it substantially better than a barrel with straight deep flutes?
I follow the folks (online) who stretch the humble .22LR out beyond 1000 yards, and hope to do the same myself one day soon.
Take care,
warren

Hello Warren,
It just happens a few months back an owner of a very well, well, well, known producer of .22 rifles was present when a pair of .416's were present. Both essentially identical except for the barrels. He noted, paraphrasing, " I would not have believed it if I was not there/shooting". He was shocked/impressed that a wide range of test rounds performed within the same impact point at the 100yd test/sight in but also continued to perform down range (let's say up to 2miles). The recoil pulse was not comparable. He ordered three barrels that day and they are in process. We have barrels running for a couple of 22ELR guys and - sshhhh- air gun guys.
Flutes- all weaken a structure in some axis unless they are very deep. Standard fluting on "normal" barrels will increase area by low 10-15% ranges (calcs available) and will reduce the bending moment of the barrel. You would need near vertical to vertical surfaces to reduce the bending moment. They will not match a closed structure weight for weight.
To be honest- we have always tried to steer people away at the smaller calibers. The returns start dropping with caliber. We have never wanted to sell "snake oil" even by mis-understanding very small gains. However, small gains at some point do matter. Now- on our AR-10's --- that is a different matter....

 

[John Baker]

So Finally.... the planets aligned. The weather cooperated. Thanks to @pmclaine had a beautiful pasture to set up to 550 unknown... it was a great day to fire the structured barrel.

First, however... We humped posts, steel targets, hit lamps, hangers, etc. out to 550 yards or so. I calculated the distance we walked up and down the pasture with gun bags, scopes, mats, ammo cans, packs, steel, posts... we did some 4 miles of 'loaded marching' before we could even begin to shoot. But immediately sighted in my .14 Eichelberger. New/old USO 10x scope on it. Got it on paper and then driving tacks. And then helped some of Pmclaine's friends with their rifles. Fixed a scope base. Got them shooting good groups. And generally helping out with some coaching.

So finally around noon got out the structured barrel. Refresher... Model 700 Magnum Bolt Face rifle poked and stroked by Fritz Alquist. KRG W3 chassis. .300 win Mag .339 NK chamber reamer in structured barrel. USO SN-3 Scope in a Sphur mount. Shooting prone off a mat. With bipod and a rear bag made from a sock filled with gutted out Beanie Babies. Some know that story. Anyway, pretty rustic setup. But it was a stable setup in what I call some perfect conditions. Light was great. Mirage was not huge... but helped read wind. Wind was up and down from calm to about 7 - 12 mph full value from right. But it was coming and going. So if you waited a few seconds, the wind was not a factor.

Ammo I will refer to as... junk. This plays into my impressions later. And it's not really 'junk' but it's not made for this rifle. Or to shoot seriously. It's part of about 400 rounds I made in 2019 for my Mk 13 Mod 0 ex Seal rifle. And they were only made for fireforming to that rifle. Nothing else. I don't remember the exact charge (I will post later) but I think it was RL 22. Boolits were something I bought cheap here on SH. Again just for fireforming. In 2019, I fireformed about 100 rounds for the Mk 13 and loaded some real tack-driver rounds for the Mk 13. And the rest sat in an ammo can. It's one of the reasons I picked that Cal for the Structured barrel. Because I know I have a track record loading for it. It's a good testbed.

So for the firing... I was pretty dialed in from earlier sighting in.

First few shots were confirming zero. Gunsmith had zero'd it using ammo I sent him. So it only took a couple of shots to confirm that it was right on at 50 where we had a target set up for fixing hunting rifles and for getting the MRAD and Eich. on paper.

First three shots were through the same hole. Not surprising at merely .50. But the group was tiny. Somewhat surprising for 'junk' ammo. but more on that later.

Fired a few more shots at a popper at about 75... then a square at 100. Then proceeded to simply whack steel with one round after another at 300 - 350. Then reached out to one of our 'far' targets. I'd miscalculated the 'drop' on the .300 WM at that range. So hit below the steel. But apparently the windage was dead nuts. Because I cut the T-post off a couple of inches below the steel and the whole target dropped like it was shot. It was pretty funny. But looking later at the T-post. The windage on the rifle had to be dead nuts, even if the boolit dropped more than I predicted (probably because fireform rounds were not 'hot.'.

Phil fired a few shots... and got the only picture of the day. And the landowners/locals got behind it and proceeded to not miss a thing... just whack steel out to about 350 - 400 like they were plinking .22's.

So this kind of confirms one of the first things that I've been 'reading' about the barrels is that they seem to be ammo-friendly. That said, it's hard to judge off one single load. Even if we did fire a bunch of them. If the rifle was doing this with my 'junk' fireforming ammo, I am going to be impressed as hell with ammo I tailor to this barrel/gun. ** But the conversation earlier in this thread about how the structured barrel is 'ammo friendly' and can digest lots of 'range' of loads would not surprise me. Again, until I start really working on ammo and ladder charges and the like, I won't know for sure.

The interesting thing was both the recoil and the 'feel' of shooting. The gunsmith who put it together commented that it was 'wierd watching my hits at 100 through the scope.' This was immediately apparent. This gun recoils like a .308. Not a .300 Win Mag. And the 'Feel/sound' of the shots is totally different. We all know that sharp crack/snap of a magnum. (or the "pinging" of an AR) when we hear/feel it. This was different. More of a 'hollow boom.' Like distant artillery. And the impulse was sort of a 'shove.' Not the kick of a .300 WM. (And BTW, I'd just fired a .300 Weatherby Mag from a pencil barrel Rem 700 hunting rifle a few minutes before. That smarted.) Even Pmclaine commented that it didn't feel like a Magnum (he can chime in). But like a .308.

I can't talk much about barrel heat. But it never got beyond warm. I grabbed the barrel after shooting. Warm. It was in 'some' sun out, but was overcast and only in the 60s. So I can't comment on cooling at this point. But don't doubt it cools well. Just didn't fire long strings to do any comparisons.

Next step is to load 'for' this barrel. And if yesterday is any indication, my initial instincts about this and my belief in TACOM are confirmed. And with spring 'really' coming to VT. I will be able to get some more brass fireformed and load up 100 rounds of tack driving ammo soon. And ammo that extracts better. Again, my bad not the gun's.

View attachment 7855900

The only picture we got of the Structured barrel yesterday. Pmclaine holding it. I don't think he wanted to give it back.

Anyway, this is initial impressions. The biggest thing, I think, that I notice right off is the recoil impulse. I had read about it... and been told about it. But until you shoot it, you don't appreciate it. I definitely want to understand the physics better. I am assuming that the 'structure' of the barrel is absorbing recoil impulse? Maybe spreading the impulse into the structure rather than straight back? Enquiring minds want to know. But until you shoot it, it sounds like voodoo. Until you shoot it. Does 'recoil impulse' make the structured barrel game-changing? Alone, of course not. But what is happening I think does make it a gamechanger for the ELR game or some other critical roles. I just don't yet understand it all well enough yet. But we will. Whatever is going on, the first shooting was impressive. Moreso because of the ammo.

Thanks to John Baker and everyone who has contributed to this so far. It's a great journey that's just beginning. Thanks, esp. to Pmclaine for sharing his shooting honey hole and his company while everything up here is still a semi-frozen swamp. And, as always, thanks to SH for being the petri dish for all this cool stuff.

More to follow! But, yeah, this was a barrel worth waiting for. Can't wait to see what it'll do with some 'real' ammo!

Cheers,

Sirhr

* Edit. Load was FC case, once fired. Full length resized. CCI Magnum primer. 62.8 Gr. Reloader 22. 220gr HPBTM Sierra. COAL 3.325 No attempt made to seat out to lands. Again, made to fireform in my Mk 13. Not the Structured Barrel.


** A side note. I was having trouble with this ammo in my chamber. Some would not chamber, so I set it aside. I know it works in the Mk. 13. Some chambered fine. I chalk this up to necks that are not perfect and that I was fireforming only. Also some would not extract after firing. A 'touch' with a cleaning rod and they fell out. But the Rem extractor was just not quite grabbing on some of the fireforming cases. The cases that did work, I will be using to make proper ammo, up to and including neck turning.

Recoil... hurts my head trying to think about it.
The structures second primary goal is to direct the "shock" waves/vibration. Water in a pipe. Electricity in a wire. Tuning forks vibrate specifically in a given direction. We can't stop the waves (yet- working on that one) but we can put them where we want them.
I like engine comparisons- pre-ignition or detonation. An explosion within the chamber has occurred at the wrong time and at a wrong "time line/period". This "explosion" puts holes in pistons- as I know within a few revolutions of the crank. Just thinking out loud- ladder tuning is both "timing" the event and creating the length of time the event will take place. The barrel is acting "in time" or as the detonation event - uncontrolled.
Instead of a "violent explosive" event vibrating in all directions - it is focused in one direction creating push- a limited vector. I think it is easy to assume the sinusoidal explosive event stops at the action. However, it continues into the stock (that's why we isolate our actions), to your shoulder and face, to your body that at some point "grounds" out the energy.
We have multiple design enhancements in the works- all to reduce recoil, improve barrel life and further improve shot string count.

Let us know when you are ready to build an optimized barrel...

 

[John Baker]

A somewehat controversial idea has been keeping my attention lately related to this thread:

I am extremely curious how a shorter length (11.5-18") structured barrel performs by comparison to traditional barrels in the same length, especially with projectiles of the .224-.308 diameter flavor...

We have built 16" barrels. Within reason a scaling can be applied at the shorter lengths- not so easy on the bigger stuff.
The same rules apply- as we go for minimum weight the positive attributes will go down but will always exceed a same weight solid barrel. The short length is of interest also to use as part of a suppressor system... in case you are looking down that road.

 

[Leftie]

We have built 16" barrels. Within reason a scaling can be applied at the shorter lengths- not so easy on the bigger stuff.
The same rules apply- as we go for minimum weight the positive attributes will go down but will always exceed a same weight solid barrel. The short length is of interest also to use as part of a suppressor system... in case you are looking down that road.

@John Baker, this is interesting, and your assumption would be correct that the short length is of interest due to the positive attributes that you mention (and @pmclaine and @sirhrmechanic have validated firsthand) above. My interest is particularly related to semi-automatic platforms, as I am also wondering if, on top of superior ballistic performance, there is an advantage in how the recoil impulse is distributed and affects the shooter.

Another question - when you mention using the structured barrel as part of a suppressor system, are you alluding to its use in an integrally-suppressed system, or a system that employs the use of a separate suppressor mounted at the muzzle? Asking as I assume that the latter might also impart different harmonics to the system as compared to an integrally-suppressed system that you all design and tune for the application. Please correct me if I am wrong here.

 

[John Baker]

@John Baker, this is interesting, and your assumption would be correct that the short length is of interest due to the positive attributes that you mention (and @pmclaine and @sirhrmechanic have validated firsthand) above. My interest is particularly related to semi-automatic platforms, as I am also wondering if, on top of superior ballistic performance, there is an advantage in how the recoil impulse is distributed and affects the shooter.

Another question - when you mention using the structured barrel as part of a suppressor system, are you alluding to its use in an integrally-suppressed system, or a system that employs the use of a separate suppressor mounted at the muzzle? Asking as I assume that the latter might also impart different harmonics to the system as compared to an integrally-suppressed system that you all design and tune for the application. Please correct me if I am wrong here.

Our Semi's have low recoil pulses- according to multiple third party guys- below normal AR10's they shoot. On bases our AR's are by far the most popular guns to shoot. Plus accurate- we had a German team shoot at SHOT. We were effectively engaging a 6" target at 980yds. They noted that under normal circumstances they would never do that with their gas guns. We use an AR10 with our little Alpha optic flipping between 100yds and 1000yd targets- that always brings the "WTF smile factor". PRS guys have noted that our 15lb AR10 in 260Rem has a recoil pulse that is just a bit more/same as their 6Dashers - easily used on barricades.
Suppressor- we have real estate (surface area for cooling) to give back. Using the internals of the barrel allows us to drastically shorten any suppressor. Our brakes can either enhance air flow through the barrel or redirect it. Suppressors have little to no impact shift change with our standard barrels. The light weight versions would have to be tested.
Heat is one of the reasons we recommend cryo as a treatment. Stress within the metal will absolutely change how it performs with the stress points adding unknowns and - continue to shift as further heat is applied. The heat changes the harmonics and moves the nodes.

 

[pmclaine]

I have very little .300WM experience.

@sirhrmechanic 's rifle is a pussycat to shoot. Easily able to see my hits at even "close" targets at approx 400 yards.

My .308s tend to be lighter weight guns with wood stocks. Ditto 30-06 in Springfield 03, M1 Garand or Model 70 flavors, the Win Mag certainly felt tamer than an 03 with steel BP, and my .308 wood M40s beat me up with enough rounds fired.

Though not an amazingly light rifle the mass of that barrel has you think your about to lift one thing and you are surprised to realize reality is another thing. Thats a regular brake on their yet with the girth of the barrel it looks like the Moel has done his work.

I'm impressed with the matching possibility of boring back along the barrel and keep everything straight.

We need a builders video of that process in action if not top secret.

 

[TriggerJerk!]

So does anyone have any new range and/or test reports on structured barrels? There hasn’t been any posts since April.

Here is an article that might be of interest to folks following this thread:

Studying Barrel Drift (Structured vs Conventional Barrels)

What is the most effective way of testing barrel drift? Can barrel drift be mitigated without the use of prohibitively heavy barrels? To what degree is heat the largest contributing factor to this phenomenon. Of all the testing that Coastal has done over the last few years, this may be the most...

www.coastalprecisionconsulting.com

 

[Crabnebula]

So does anyone have any new range and/or test reports on structured barrels? There hasn’t been any posts since April.

Here is an article that might be of interest to folks following this thread:

Studying Barrel Drift (Structured vs Conventional Barrels)

What is the most effective way of testing barrel drift? Can barrel drift be mitigated without the use of prohibitively heavy barrels? To what degree is heat the largest contributing factor to this phenomenon. Of all the testing that Coastal has done over the last few years, this may be the most...

www.coastalprecisionconsulting.com

Im just getting my structured barrel prepped for elr. More to come

 

[Crabnebula]

 

[iceng]

Wait... You put a structured barrel.... On.. a savage.. ?

 

[Crabnebula]

Yep the action I had was indeed a savage two lug . I wasn’t able spend 1300$ on a custom action. It will work just fine….. the action was custom “mated” to the barrel as per à Ogive OAL length, for .210-.230 grain bullets at a length beyond SAAMI. A custom chamber. So anyways, no barrel nut. Recoil lug at 6 o clock may be the weakness . But I’ll be able to shoot this out to a 1300-1700 yard line which was the goal

 

[Crabnebula]

Here are two savage action. One w barrel nut on a shilen barrel. One with out with Kreiger/ structured barrel. Both in MDT chassis.

Ive had really good luck with shilen barrel easy peasy out to 1280 yards all day with 175 gr smk loaded with 40.2 Varget etc

 

[Crabnebula]

John mills also helped get mine custom chambered. Very pleased with the whole
Process

Tacom hq knows that what they do works

Mine is chambered I .308/ 1:8 twist / set up for .210-.230 smk

 

[TriggerJerk!]

Im just getting my structured barrel prepped for elr. More to come

Great to hear, and thanks for the pictures. Definitely let us know your results as you work up a load and get some testing done.

 

[NamibHunter]

Any update on how these structured barrels SHOOT at long range (past 1500 yards)?

 

[brianf]

Any update on how these structured barrels SHOOT at long range (past 1500 yards)?

Same here trying to find real info not one off stuff

I think the idea has kegs

 

[msgriff]

Same here trying to find real info not one off stuff

I think the idea has kegs

Sounds like a party. I'm in.

 

[Crabnebula]

Wait... You put a structured barrel.... On.. a savage.. ?

It is a higher end savage action, that was custom chambered and put into an mdt chassis

 

[Crabnebula]

Also have loads all build .210 smk and using Varget ~ 39.7 grains? I can’t remember

It is grouping 3-5 inch x 5 shots at 1000 yards

Ill get photos and etc later

 

[Crabnebula]

Basically. Kreiger barrel with all the add ons possible from
Tacom hq

This is likely the best of all the elr/ precision rifles I have shot. And by far the best and most expensive rifle I own

As the loads and bullet choices I have been experimenting with comes to fruition …. I am realizing it doesn’t really
Matter. It is just an absolute enjoyable experience to shoot

Anyways

Ill try to
Get some pictures tomorrow

 

[Zak Smith]

Wait, send a close-up of those muzzle threads please, side profile, macro

 

[E. Bryant]

Wait, send a close-up of those muzzle threads please, side profile, macro

Are you suggesting that it's a bad idea to have interrupted muzzle threads?