Can a different muzzle device change barrel harmonics and effect accuracy

[LC 6.5 Shooter]

Question can a new muzzle device throw off a load/barrel harmonics. I just got my new Thunderbeast and put the TB brake on and the ultra 7 and it didn’t group anywhere near normal.

I also tried a new apa gen 3 fat bastard instead of the gen 2 I had on and it didn’t group. Just curious if you have seen that. Ive never swapped anything like that mid barrel life. This is a 6 dasher on a mullerworks barrel chambered by ATeam that generally shoots 0.3” or better all day. Groups were 0.5” and greater. This was also shot on a clean barrel.

 

[LC 6.5 Shooter]

Could have just been a shitty shooter on tje trigger that day too

 

[308pirate]

In theory yes. In practice, it depends.

 

[hlee]

Thunder chicken put the precision of my RPR in the crapper, but didn’t even change the POI of my Grendel AR15. Yes, a different muzzle device CAN change how a rifle shoots.

 

[rijndael]

Question can a new muzzle device throw off a load/barrel harmonics. I just got my new Thunderbeast and put the TB brake on and the ultra 7 and it didn’t group anywhere near normal.

You might find that a tuner helps you swap between muzzle devices while maintaining your tight groups.

 

[LC 6.5 Shooter]

You might find that a tuner helps you swap between muzzle devices while maintaining your tight groups.

I have an ATS I can use. Might throw it on and try it if it persists.

 

[THEIS]

Hi,

.3" or better all day??

Just giving you a hard time but.....

You and that rifle need to go clean up the IBS matches, lol

Sincerely,
Theis

 

[1moaoff]

100 you pics please. 5 shot groups as in multiple from same day... go ahead and put the original device back on to shoot groups.

Seriously though any change to barrel or load will change harmonics. Be it good, bad, or neutral!

 

[rijndael]

Seriously though any change to barrel or load will change harmonics. Be it good, bad, or neutral!

Look at how much a tuner can change things by simple moving weight along the barrel, in very small amounts.

 

[LC 6.5 Shooter]

Hi,

.3" or better all day??

Just giving you a hard time but.....

You and that rifle need to go clean up the IBS matches, lol
View attachment 7723251
View attachment 7723253
View attachment 7723255

Sincerely,
Theis

Lmao ok its usually way more accurate than it shot with that being the only change.

 

[BLKWLFK9]

Before barrel tuners became popular in our game, i use to use washers behind my suppressor to tune in different factory loads. I heard David Tubb mention it and figured i would give it a try. Turns out it worked. It was 2 washers for the OG prime ammo, 1 for federal 130 hybrid, and none for hornady match 140 eldm. The results were most definitely repeatable. If just changing the weight difference of a washer or 2, you can bet that the difference of a brake, can, tuner, etc. will have equal or greater affect.

 

[kthomas]

Before barrel tuners became popular in our game, i use to use washers behind my suppressor to tune in different factory loads. I heard David Tubb mention it and figured i would give it a try. Turns out it worked. It was 2 washers for the OG prime ammo, 1 for federal 130 hybrid, and none for hornady match 140 eldm. The results were most definitely repeatable. If just changing the weight difference of a washer or 2, you can bet that the difference of a brake, can, tuner, etc. will have equal or greater affect.

Interesting.

 

[LC 6.5 Shooter]

Before barrel tuners became popular in our game, i use to use washers behind my suppressor to tune in different factory loads. I heard David Tubb mention it and figured i would give it a try. Turns out it worked. It was 2 washers for the OG prime ammo, 1 for federal 130 hybrid, and none for hornady match 140 eldm. The results were most definitely repeatable. If just changing the weight difference of a washer or 2, you can bet that the difference of a brake, can, tuner, etc. will have equal or greater affect.

Good info. Thanks. I’ll probably throw my ATS tuner on and see if it can squeeze things back down.

 

[huntnh]

Yes it can Iv got one gun that hates brakes Iv tried multiple brands. Goes from .5 to 1.5 groups

 

[Greg Langelius *]

The muzzle device will cause harmonics to operate at a different frequency from the plain muzzle, maybe.

The 'maybe' comes when the device causes the muzzle to harmonize with the plain muzzle, I.e., vibrate a multiple of that same original harmonic frequency.

It's usually a coincidence, but it does happen.

Greg

 

[brianf]

There should be a mandatory 5 day ban on anyone who says “all day long” anymore

 

[Greg Langelius *]

The washer gambit is a good fix.

You can buy the washers at gun distributor prices (approximately $2.50 each, plus tax and shipping), or shuffle on down to the local hardware store and buy them in bags for a lot less, 1/2" and 5/8" ID.

That G. David Tubb guy is one Canny Dude.

BTW, they will also work behind a thread protector.

In a pinch, you can wrap rubber bands around the muzzle, then weigh them on your powder scale to get an approximate equivalent washer weight.

A key point to understand is that precision tuning can be too precise and be subject to going sour with weather deviations, which is why the really good ones are adjustable. Better is good, perfection can be frustrating. Do a Search for "Temperature and Natural Harmonic Frequency".

Getting a rifle to shoot at its absolute best can become an exercise at hitting a moving target; some can, and can keep it despite changes; most other's can't and (maybe wisely) are willing to settle for pretty close.

If you wonder what I mean, visit a BR match sometime.

This is one reason why I'm willing to give up some small margins of extreme accuracy in the interests of maintaining one's sanity.

Greg

 

[LC 6.5 Shooter]

There should be a mandatory 5 day ban on anyone who says “all day long” anymore

There should be a mandatory 10 day ban for douche bags who cant look past a statement to answer the question at hand. Go troll somewhere else if you dont have any value to add. I retracted the statement after the other member “kindly” pointed it out.

let me rephrase it so your peanut sized brain can comprehend the question. After installing new muzzle devices the gun shot notably less accurate. Could have been a bad shooter day. But wanted to see if anyone else had seen similar issues.

NY-now I get it

 

[LC 6.5 Shooter]

The washer gambit is a good fix.

You can buy the washers at gun distributor prices (approximately $2.50 each, plus tax and shipping), or shuffle on down to the local hardware store and buy them in bags for a lot less, 1/2" and 5/8" ID.

That G. David Tubb guy is one Canny Dude.

BTW, they will also work behind a thread protector.

In a pinch, you can wrap rubber bands around the muzzle, then weigh them on your powder scale to get an approximate equivalent washer weight.

A key point to understand is that precision tuning can be too precise and be subject to going sour with weather deviations, which is why the really good ones are adjustable. Better is good, perfection can be frustrating.

Getting a rifle to shoot at its absolute best can become an exercise at hitting a moving target; some can, and can keep it despite changes; most other's can't and (maybe wisely) are willing to settle for pretty close.

If you wonder what I mean, visit a BR match sometime.

This is one reason why I'm willing to give up some small margins of extreme accuracy in the interests of maintaining one's sanity.

Greg

Thank you Greg.

 

[Greg Langelius *]

I spent one entire Summer trying to concoct my own homemade harmonic barrel tuner. It worked too well (way too much mass) and I abandoned it when I concluded that no adjustment I made with it would be any good as soon as the next day.

I learned a lot of practical knowledge about tuners. The first one is that the smaller the weight, the less sensitive it is to environmental variance, and conversely, that it takes more displacement to achieve the desired result. This why washers work better, they have less mass.

As temperatures increase, barrels oscillate faster. This corresponds to moving the weight away from the muzzle. So, as temps increase, we correct by moving the mass closer to the muzzle, slowing down its oscillations and bringing it back into sync with the bullet's barrel transit time. With a non-adjustable tuner, add another (or more) washers.

Temps up, more mass or closer to the muzzle. Temps down, less mass, or move the mass away from the muzzle. Maybe this will help someone avoid excessive tuning shots.

Finally, don't get carried away, because adjusting shots add to bore wear without adding to scores. It adds up fast. I quit when I realized I was upon the verge of going down the rabbit hole and killing a beautiful barrel.

There is nothing wrong or incurable about adding a new muzzle device. Any resulting accuracy issues can be resolved simply and quickly. Just apply the above info about adding and deleting washers (or suchlike) to tune the new device's overall mass into sync with your load's barrel transit time.

I once considered putting threads and protectors on every new barrel was a dumb idea. But now, I understand how they provide a simple and inexpensive way to tune mundane barrels to greater accuracy.

BTW Camillius was the place where I would watch the BR shooters at their game back in the twenty-zeros. I learned a lot by simply talking to some of the very best shooters on the planet. Few people understand accuracy more than they do. The same thing happens at Bodines out to 1000yd.

Greg

 

[Snuby642]

Every difference in what hangs off the end changes harmonics.

Maybe resolved with seating depth maybe just impact, sometimes powder adjustment. It has no set rule or result.

Imho

 

[spife7980]

Can a different muzzle device change barrel harmonics and effect accuracy​

I would say that you have already proven to yourself that it very well can...

 

[DJL2]

Haven't shot enough bolt guns in enough configurations to say for sure... but, I will say that enough people believe that there is a significant issue here that barrel tuners are a product that sells. They've been semi-mainstream at least since Browning introduced the BOSS back when (and probably earlier).

I do have a good news story:
I have a 6.8 SPC AR... it's normally about a 1.5 MOA rifle. I put the Tranquilo on it, and all of a sudden it's a 1 MOA gun. It's uncanny. I had it out yesterday and dropped 5 rds into less than MOA @ 400 yards (my 110 VMax handloads) just verifying DOPE/come ups. The only time I can ever remember it printing at, or below, MOA is with the can on. Could it be chance? Sure could, small samples and all that... I just like to believe in magic ;-).

 

[1moaoff]

Look at how much a tuner can change things by simple moving weight along the barrel, in very small amounts.

Yes, that's why I said that.

 

[1moaoff]

Haven't shot enough bolt guns in enough configurations to say for sure... but, I will say that enough people believe that there is a significant issue here that barrel tuners are a product that sells. They've been semi-mainstream at least since Browning introduced the BOSS back when (and probably earlier).

I do have a good news story:
I have a 6.8 SPC AR... it's normally about a 1.5 MOA rifle. I put the Tranquilo on it, and all of a sudden it's a 1 MOA gun. It's uncanny. I had it out yesterday and dropped 5 rds into less than MOA @ 400 yards (my 110 VMax handloads) just verifying DOPE/come ups. The only time I can ever remember it printing at, or below, MOA is with the can on. Could it be chance? Sure could, small samples and all that... I just like to believe in magic ;-).

It was a 1MOA gun before.... just saying.

 

[1moaoff]

There should be a mandatory 10 day ban for douche bags who cant look past a statement to answer the question at hand. Go troll somewhere else if you dont have any value to add. I retracted the statement after the other member “kindly” pointed it out.

let me rephrase it so your peanut sized brain can comprehend the question. After installing new muzzle devices the gun shot notably less accurate. Could have been a bad shooter day. But wanted to see if anyone else had seen similar issues.

NY-now I get it

Oh just run with it and laugh!!!! You made the statement. And the fact you are asking the question isn't necessarily bad, but it does show that you are newer to this and don't spend a lot of time researching or reading about the basics.

Now for the snarky part..... spend less time shooting your .3333 groups all day and do a .333 tiny bit of research and you wouldn't have gotten the crap you did.... just laugh it off!!

 

[SupressYourself]

I just found out the other day that a fabric suppressor cover can make a much bigger difference than expected. The same load shot a solid 1 inch higher, and significantly tighter at 100 yards with the cover off.

 

[THEIS]

Hi,

We shall see; as I have 4 different rifles in load development right now with PVA monos and PVA brakes.
The day before the precision rifle expo we will put KGM Technologies suppressors on them and see what changes with each rifle/load.


Sincerely,
Theis

 

[Greg Langelius *]

Snuby, I do different things for different purposes.

I handload for consistency and reliability, especially in feeding and velocity.

I believe tuning the barrel is the place to find accuracy. Once I have my velocity, I should be tuning my barrel to make it accurate.

I've never tuned seating depths beyond getting a good max mag feeding length. I tune powder charge for consistent velocities and bore life. I don't beieve in velocities greater than getting the bullet on target at 1300fps or so. All bullets have drops and drifts, and compensating for them is simply a basic shootng skill. Using greater velocity to simplify this kills barrels, and we don't need that. I've never had a need for a first shot hit at extended range, my hunting distances are based on my ability to retrieve my kill, and that isn't measured in big distances.

Greg

 

[Conrad101st]

I put a silencerco ASR flash hider on my LMT MWS. POI shifted about 1.25 inches left at 100 yards. Group size stayed about the same.

 

[Snuby642]

Well @Greg Langelius *
I'm not sure I get your point.

I have tested different muzzle devices including suppressors on the same load in 6.5, 308, 300blk 223 and 22 lr on different type barrels.

Everyone had measurable changes, some drastic. Some could be compensated for with load adjustments and some not.

I have found recently to me that tangent ogive and hybrids are easier to re-tune.

I find seating depth testing annoying, but productive for some bullets.

In fact I dred my next change to a load I made for my sons 308, 165 sgk and some of our remaining varget.

It was an ocw test and came out sub half inch, most of the rest were sub moa.

The only reason I'm touching that is minor hard bolt, lift possibly right up to the lands (less than 0.010).
The 165 is a tangent ogive and I hope this works.

 

[Greg Langelius *]

Snuby, my only point is that many paths lead to a similar destination. Mine will likely be the easiest one.

I try to avoid seating that close to lands because I find that the ogives vary enough that some will engage, and some will not. I worry that this will impede maximum accuracy. If you measure your depth off the Ogive, you should be fine. I measure COAL, not ogive.

Best fortune and safe shooting. My IMR-4064 Accuracy load for that bullet is 43.5gr, same as my 168 FGMM Clone. The Varget load should end up around within .5gr of that.

Greg

 

[brianf]

There should be a mandatory 10 day ban for douche bags who cant look past a statement to answer the question at hand. Go troll somewhere else if you dont have any value to add. I retracted the statement after the other member “kindly” pointed it out.

let me rephrase it so your peanut sized brain can comprehend the question. After installing new muzzle devices the gun shot notably less accurate. Could have been a bad shooter day. But wanted to see if anyone else had seen similar issues.

NY-now I get it

no need to name call

Does it matter if you are the only one it ever happened to?

no…because it’s happening.

and if your shooting in the “3’s” like you say, you already have all the data you need…people should be asking you

 

[Snuby642]

Thanks for the heads up on the IMR4064 Greg. My varget will make it through this hunting season for the hunting loads only.

I have to find a replacement for varget been up all hours trying to get some.

50 yard 3 shot initial ocw test set to Sierra specs and if I can get rid of slight bolt lift problem will be his primary hunting load.

 

[Greg Langelius *]

IMR-4064 and Varget perform nearly the same for me, with the Varget having the advantage of less temperature sensitivity.

I always tend to cringe a bit when I deal with stiff bolt lift; it tells me I'm outside my comfort zone.

I would start with 42.0-42.5gr of IMR-4064 and work up from there. My sweet spot in M1A and Savage 11FV is 43.5 with 168 HPBT's and my tests with that load and 165SGT showed only a 2" right POI shift and no difference in group size at 200yd.

When I'm out of both, I work up with H-4831SC. My tests tended to be down a bit on velocity.

Just reviewed the Hodgdon site, they have reduced all their max loads for IMR-4064 and Varget by one full grain. Doesn't affect my loads.

Greg

 

[GHDIII]

I put a new barrel on my Tikka in .270 win. Sub moa all day with no muzzle device. Put on a Precision Armament brake on it and it could barely shoot 2 moa. Threw on a Killer Innovations killer B and I'm shooting 3/4" groups at 200 yards with littleeffort. I put a Tac Sol radial brake on my 10/22 and it shot exactly that same as no brake. Ended up throwing a Maxim Hate Brake on it to reduce the signature at night and the gun couldn't reliability hit a bottle cap at 25 yards. Then threw the same Hate Brake on my CZ 457 in .17 HMR and it's a laser. Laser...
The struggle is real.

 

[Vicdiesel]

I’ve read that over tightening a muzzle device can cause groups to open up…
I actually have a rifle I’m worried I over tightened a TB brake on… I haven’t shot it since installing the brake though…

 

[Sasquatch-148]

Question can a new muzzle device throw off a load/barrel harmonics. I just got my new Thunderbeast and put the TB brake on and the ultra 7 and it didn’t group anywhere near normal.

I also tried a new apa gen 3 fat bastard instead of the gen 2 I had on and it didn’t group. Just curious if you have seen that. Ive never swapped anything like that mid barrel life. This is a 6 dasher on a mullerworks barrel chambered by ATeam that generally shoots 0.3” or better all day. Groups were 0.5” and greater. This was also shot on a clean barrel.

Absolutely can , on any caliber . I trued a few different ones on my 22s even , they messed up my groups big time . My suppressors sometimes change poi , but the groups are just as good as ever .

 

[Jim Boatright]

I spent one entire Summer trying to concoct my own homemade harmonic barrel tuner. It worked too well (way too much mass) and I abandoned it when I concluded that no adjustment I made with it would be any good as soon as the next day.

I learned a lot of practical knowledge about tuners. The first one is that the smaller the weight, the less sensitive it is to environmental variance, and conversely, that it takes more displacement to achieve the desired result. This why washers work better, they have less mass.

As temperatures increase, barrels oscillate faster. This corresponds to moving the weight away from the muzzle. So, as temps increase, we correct by moving the mass closer to the muzzle, slowing down its oscillations and bringing it back into sync with the bullet's barrel transit time. With a non-adjustable tuner, add another (or more) washers.

Temps up, more mass or closer to the muzzle. Temps down, less mass, or move the mass away from the muzzle. Maybe this will help someone avoid excessive tuning shots.

Finally, don't get carried away, because adjusting shots add to bore wear without adding to scores. It adds up fast. I quit when I realized I was upon the verge of going down the rabbit hole and killing a beautiful barrel.

There is nothing wrong or incurable about adding a new muzzle device. Any resulting accuracy issues can be resolved simply and quickly. Just apply the above info about adding and deleting washers (or suchlike) to tune the new device's overall mass into sync with your load's barrel transit time.

I once considered putting threads and protectors on every new barrel was a dumb idea. But now, I understand how they provide a simple and inexpensive way to tune mundane barrels to greater accuracy.

BTW Camillius was the place where I would watch the BR shooters at their game back in the twenty-zeros. I learned a lot by simply talking to some of the very best shooters on the planet. Few people understand accuracy more than they do. The same thing happens at Bodines out to 1000yd.

Greg

I did all of my barrel vibration calculations for a barrel temperature of 21 degrees Celsius (C). Using the handbook decrease in Young's Modulus of Elasticity for all steels of about 5.0 GigaPascals (-5 GPa) per 100 degree C temperature increase, and using a coefficient of linear thermal expansion of 12x10^-6 per degree C for 416R stainless steel, each mode vibration frequency would be 1.2 percent LOWER at a barrel temperature of 121 degrees C. This includes the thermal increase in barrel length and cross-sectional area as well as the decrease in material density with that 100 degree C rise. I was more interested in calculating "cold bore" point-of-impact. BTW, since the bulk modulus and shear modulus of elasticity are directly related to Young's modulus, they also decrease proportionally with increasing material temperature (about -2.5 percent per 100 degrees C increase), so the shear-wave propagation rate decreases by about 1.08 percent per 100-degree rise. Tensile strength variations are a whole different animal. Many steels reach their maximum strength at about 100 degrees C.

I will happily send you, or anyone, my Excel spreadsheet for these muzzle motion calculations if you will email me at <[email protected]>. It also uses inputs from running your loads in QuickLOAD(c).

 

[Jim Boatright]

I’ve read that over tightening a muzzle device can cause groups to open up…
I actually have a rifle I’m worried I over tightened a TB brake on… I haven’t shot it since installing the brake though…

Yes, Vic, tightening 60-degree V-threads radially compresses the barrel steel inside the loaded threads and inside the nearby load bearing surface, and it can be a lot if you crank on any threaded joint. The greatest compression is just inside the receiver face with threaded barrels and just behind the muzzle for barrel attachments. Over-torquing barrels compresses the chamber enough that headspace gauges indicate a short chamber for bottlenecked cartridges. That is why armorers use "pull" type chamber finishing reamers for installed 30-caliber M1 and M14 barrels, and why US designers always specified Acme (almost square) threads for military threaded barrels.

 

[Steel head]

I did all of my barrel vibration calculations for a barrel temperature of 21 degrees Celsius (C). Using the handbook decrease in Young's Modulus of Elasticity for all steels of about 5.0 GigaPascals (-5 GPa) per 100 degree C temperature increase, and using a coefficient of linear thermal expansion of 12x10^-6 per degree C for 416R stainless steel, each mode vibration frequency would be 1.2 percent LOWER at a barrel temperature of 121 degrees C. This includes the thermal increase in barrel length and cross-sectional area as well as the decrease in material density with that 100 degree C rise. I was more interested in calculating "cold bore" point-of-impact. BTW, since the bulk modulus and shear modulus of elasticity are directly related to Young's modulus, they also decrease proportionally with increasing material temperature (about -2.5 percent per 100 degrees C increase), so the shear-wave propagation rate decreases by about 1.08 percent per 100-degree rise. Tensile strength variations are a whole different animal. Many steels reach their maximum strength at about 100 degrees C.

I will happily send you, or anyone, my Excel spreadsheet for these muzzle motion calculations if you will email me at <[email protected]>. It also uses inputs from running your loads in QuickLOAD(c).

 

[BLKWLFK9]

View attachment 7725264

Big facts.

 

[John Baker]

Light weight hunting rifles vs dedicated target of any kind is a rough oranges and apples comparison at best- my humble opinion. Trends only.
For those who can run a rifle 9lbs and up our barrels might be a choice.
Structured barrels are designed to reduce the harmonic effect of powder charges, bullet weights, muzzle devices, and induced heat. We run a magneto directly on the barrel all of the time if the chassis cannot except a divorced unit- with no apparent change in group size or group shift. Turning a large brake in and out or adding washers... the effect is so small that you had better be shooting well to see the difference. In fact we moved devices up and down the thread of the barrel on purpose shooting 200yd groups- at David Tubb's.
Not only does frequency change per change in temperature it also changes shape and node position. In a past life a temperature shift of 20deg was an operating unit to a broken tool. In this case the temperature was created by an incorrect frequency not matched to a designed focused tool. Plus just because you have a piece of 416 or Chromoly does not mean you have the exact same steel barrel to barrel let alone within the same steel bar.

 

[Greg Langelius *]

No, Jim; I believe you.

My bad interpretation of some technical papers that were way over my head. I can't link because it goes directly to an enormous PDF.

Just do the opposite of what I said and it should work.

Not being able to get out and do testing is messing with my mind.

Sooo...

Being trapped at home with nothing but my computer available to me, I did some searching for something that demonstrated these things more clearly.

I came up with this from Varmint Al. In reading it several times, it dawned on me that it really doesn't matter so much whether temperature increase makes barrel vibration faster or slower because multiple nodes usually exist. What's more important is that whatever a temperature change does, adjusting the tuner will bring us back into the same node or into the adjacent node at a point that is compatible with the new temperature. The link makes no mention of temperature, by the way.

Now, then; what would be even more useful would be developing a means to use expansion due to temperature in a mechanism that compensates for the change. I'm thinking something like the bimetallic flexing that makes a thermostat work. That way, one finds the right setting for the load, and then the thermostatic compensator keeps it in tune. This could be especially useful when barrels heat up during a string of fire, dealing at least somewhat with the cold vs hot barrel behavior.

Greg

 

[John Baker]

What do shooters consider an extended string? 5shots, 10shots, 20shots... What is the goal of the shooter?
What is the acceptable precision, group size, group drift and SD drift?
A recent 6.5Creedmore was tested by a third party noting: "standard heavy barrels (PRS) start to drift at 20shots. Your barrel did not show any indication until shot 47". Another "we compensate at shots 5-6 normally and now can run to 12-15 before a compensation is required" ELR shooter running a .416". Large blogger "you can't compare your barrels with another barrel. Different league" when asked about CF compared to ours... Understood that it should be considered two different markets for CF and our barrels. However, when they are thrown together than direct comparisons can be made.
Back to the original questions. Therefore start with a superior base than look for tweeks if needed.

 

[Pesky Squirrel]

My experience-
My Kimber Montana in 243 shoots 7” lower when a YHM suppressor is attached. Groups opened.
My Tikka t3 Lite in 300 WM shoots 5” lower. Groups opened a little.
My MRC in 375 H&H groups opened over 1” dia more when I removed the factory brake.
My Mini-14 in 223 groups reduced by over 2” and shoots 5” lower with YHM.

Apparently the added weight alters things substantially IME. Sometimes for the bad, sometimes for the good. Load experimenting brought everything back to good.

Harmonics can be different on two barrels coming off the same production line one after the other. The nature of steels, machining and working.

 

[brianf]

Light weight hunting rifles vs dedicated target of any kind is a rough oranges and apples comparison at best- my humble opinion. Trends only.
For those who can run a rifle 9lbs and up our barrels might be a choice.
Structured barrels are designed to reduce the harmonic effect of powder charges, bullet weights, muzzle devices, and induced heat. We run a magneto directly on the barrel all of the time if the chassis cannot except a divorced unit- with no apparent change in group size or group shift. Turning a large brake in and out or adding washers... the effect is so small that you had better be shooting well to see the difference. In fact we moved devices up and down the thread of the barrel on purpose shooting 200yd groups- at David Tubb's.
Not only does frequency change per change in temperature it also changes shape and node position. In a past life a temperature shift of 20deg was an operating unit to a broken tool. In this case the temperature was created by an incorrect frequency not matched to a designed focused tool. Plus just because you have a piece of 416 or Chromoly does not mean you have the exact same steel barrel to barrel let alone within the same steel bar.

Was clicking around a bit…do you guys have anything from Tubb about your visit I can read or watch?

thanks

 

[EternalNoob]

It's entirely "possible". Witness the old Browning BOSS muzzle device.

 

[Greg Langelius *]

An extended string for me comprises up to 5 sighters, then 10 or 20 shots for score.

Acceptable drift, etc., is not a set thing; it varies by the tolerance of the shooter. Some will tolerate more, some less; and I think the limits are based on the shooter's abilities to detect and compensate, and they will vary with shooter.

Right now I'm holding in hand a trophy for 4th in the 1997 NJ State Sniper Championships, a paper match fired at 300yd. I fired that match with a Win 70 Featherweight 30-06 that I had obtained the previous day and sighted in with 168gr FGMM, which was also used for the match. So there are thin barrels out they which can shoot really well, but they are probably scarcer than hen's teeth

My SIL uses it for Deer in Upstate NY. Right now, that's plenty better hands than mine.

Greg

 

[Jim Boatright]

No, Jim; I believe you.

My bad interpretation of some technical papers that were way over my head. I can't link because it goes directly to an enormous PDF.

Just do the opposite of what I said and it should work.

Not being able to get out and do testing is messing with my mind.

Sooo...

Being trapped at home with nothing but my computer available to me, I did some searching for something that demonstrated these things more clearly.

I came up with this from Varmint Al. In reading it several times, it dawned on me that it really doesn't matter so much whether temperature increase makes barrel vibration faster or slower because multiple nodes usually exist. What's more important is that whatever a temperature change does, adjusting the tuner will bring us back into the same node or into the adjacent node at a point that is compatible with the new temperature. The link makes no mention of temperature, by the way.

Now, then; what would be even more useful would be developing a means to use expansion due to temperature in a mechanism that compensates for the change. I'm thinking something like the bimetallic flexing that makes a thermostat work. That way, one finds the right setting for the load, and then the thermostatic compensator keeps it in tune. This could be especially useful when barrels heat up during a string of fire, dealing at least somewhat with the cold vs hot barrel behavior.

Greg

Yes, Greg, I worked with Al Harral (VarmintAL) comparing his LS-DYNA FEA triaxial stress calculations with my hand calculations at several key locations on the bolt face, bolt lugs, and barrel swell for a Remington Model 7 in 243 Win. They agreed, but Al did not think that was possible.
Many "tactical" rifles already incorporate a bimetallic stress arrangement--an aluminum alloy scope tube rigidly clamped at two places 6 inches apart to a steel receiver with about a 1.5-inch on centers separation between the two tubes. Since the coefficient of linear thermal expansion for the aluminum alloy scope tube is about double that of the steel receiver, the scope tube is compressed between the two clamps and bent into an inverted U-shape with temperature rise above the 70-degree F room temperature when the scope was clamped. The target image formed in the scope then rises relative to a second focal plane reticle. At about 150 degrees F, the scope tube is compressed with a force of 600 pounds between the scope rings. I have long advocated use of an aluminum alloy scope mounting rail or a sliding rear scope ring similar to the externally adjusted micrometer rear scope mount.