6br tips

[Stroll]

hello all,

the more a read about the 6br the more i think i will love it, so i'm going to build one (my first build unitl now only factory).

For not spend too much i wanted use an howa 1500 SA (one-piece machined receiver and bolt)and a oryx or ess chassis. I want to use a cut-rifled barrel 28" 1:8. I want to use it for f-class out of 600y and probably prs. I don't go hunting.

i was thinking about the dasher but i don't like to shoot a brass 3-4 times just to fireform and i prefer a longer barrel life.

For optic i'm thinking the vortex golden eagle (i don't know if the 1/8 moa correction could be a problem for prs).

now the question
for barrel i like bartlein but there is a gunsmith here that has a krieger available. There is a barrel and number of grooves that is better for 6br? how about barrel life with a krieger vs bartlein vs others? suggest a profile too, the more stright the more i like(i don't know much about that). I will need a muzzle brake or is just if i want a recoil like a 22lr?

the question that make me think more is, that rifle could be competitive in open or versus a full custom?

sorry for the poem and thank you in advance

 

[MakeSawdust]

Barlein and Kreiger are equal. Lands and grooves won't matter. Buy a good cut rifled blank and have someone chamber it that is GOOD and it will shoot. To be competitive in PRS you will want the heaviest barrel profile that the rife will balance with. You want to be able to see trace for targets with no berm behind them. You will also want a brake to shoot PRS. I believe brakes are not allowed in F-Class, but not certain because I don't shoot F-Class.

The rifle will be competitive. The only things holding you back will be action smoothness, which might effect your speed slightly (you can train it away) and the trigger options for a Howa. Most customs are 700 trigger compatible and there are a lot of really good 700 triggers out there.

Other than that, if the barrel is chambered well and you use quality brass and bullets (read Lapua and Berger) the gun will shoot. They are stupid easy to load for.

 

[Stroll]

thank you for the info. Lapua and Berger is that i want to use and i will try dtac too. i will use vihtavuoti n 140/150.

because of the feed problem of the 6br i was thinking about the primal kit with AI mags or the mdt 6br mags, any thoughts?

so 1" barrel should be good

just wait for an fclass/bench shooter to see more tips on this discipline in particular.

 

[Shoots 700's]

MDT mags work flawlessly for me.

 

[Forrest84]

I just started the 6BR game and it’s been a good move so far. My only complaint
I think is tots just a bit to slow than ide hoped. I would at least go with 6bra. I’ll go to 6 dasher as soon as the Barrel goes. I’ve been using the mdt mags and they have run perfectly fine so far a
Free a
Few hundred rounds

 

[Stroll]

Thank you all

 

[BoilerUP]

I run 6BR in an ARC Nucleus and have zero feed issues using a Magpul 5rd 7.62AC.

 

[Cardboard Assassin]

hello all,

the more a read about the 6br the more i think i will love it, so i'm going to build one (my first build unitl now only factory).

For not spend too much i wanted use an howa 1500 SA (one-piece machined receiver and bolt)and a oryx or ess chassis. I want to use a cut-rifled barrel 28" 1:8. I want to use it for f-class out of 600y and probably prs. I don't go hunting.

i was thinking about the dasher but i don't like to shoot a brass 3-4 times just to fireform and i prefer a longer barrel life.

For optic i'm thinking the vortex golden eagle (i don't know if the 1/8 moa correction could be a problem for prs).

now the question
for barrel i like bartlein but there is a gunsmith here that has a krieger available. There is a barrel and number of grooves that is better for 6br? how about barrel life with a krieger vs bartlein vs others? suggest a profile too, the more stright the more i like(i don't know much about that). I will need a muzzle brake or is just if i want a recoil like a 22lr?

the question that make me think more is, that rifle could be competitive in open or versus a full custom?

sorry for the poem and thank you in advance

I have a 6BR with a 28" Krieger 4 groove and it is a sub 0.25 MOA gun. Last time I took it out I had 3 groups in the teens (~0.17) at 100M & 300M. Pretty darned happy with it.

I went 6BR for the longer barrel life over some of the other 6mm options. I listened to some podcasts from top shooters and a lot of them were going back to 6BR after having other calibers, two things I recall:

1) One guy said that he found that the throat erosion on whatever hot rod 6mm he was using that the gun would lose significant accuracy over the course of a PRS match (he figured 6BR this would be less of an issue with 6BR).

2) Some top shooters felt there was a "sweet spot" with speed for spotting trace and 6BR was a good fit for that.

I have found 6BR incredibly easy to load for, my load development involved shooting 4 powders weights over a chronograph to find the speed I wanted (~2850) and then I read an article from SAC on seating depth that lead me to believe around 75 thousandths jump was a good bet for hybrid bullets. Tried it and consistent sub 0.25 MOA.

Regarding barrel life my guess is Bartlein and Krieger would be pretty similar all things being equal *except* if you go with a new MOD400BB Bartlein barrel, supposedly these are getting much better barrel life.

If it is for PRS a heavier barrel is good (I use a 1.25" straight "truck axle" barrel but MTU or M24 etc would be good too) as weight is your friend and with a large part of PRS being recoil management to help with spotting trace a brake sure wouldn't hurt.

Like you I built the rifle for both PRS & F class (primarily PRS). Plan is to remove the brake for F class events and run it for everything else.

Regarding scopes I figured a 7-35X ATACR in MILs would be a good bet for both disciplines (MILs is a must for PRS and the fine centre dot should be accurate enough for F class) and I have a SFP 50X scope in MOA which I might switch to for F class events.

 

[iceng]

If you run aics size magazines you will have to get a 'smith to notch the front of the feed ramp.

 

[Feniks Technologies]

6br guide:

Bartlein/Krieger/proof/ xyz other reputable brands. 7.5tw. Whatever groove available. In your preferred contour

For PRS a FFP optic is basically required. Mils or MOA, doesn’t matter. If you “speak” both, you can do just fine when people speak in mils. Simple conversion. But SFP would be a bit of extra work. The golden eagle is an F class optic. Great for that. Not for this. Get a gen 2 razor (PX should be flooded now the gen 3 is out)

Load up 30 grains of Varget (or equivalent grains of n150 or other such stuff) with a Berger 105, 108, or 109. Or hornady 108. Whatever you can find.

Do seating depth test.


That’s it. 6br done. That will be more than enough to win most any prs match. The rest is on you. Trigger, mags, chassis……pick your poison.


Anything more than this is personal preference and also could very well be overthinking.

 

[GunmanBlue]

What @Feniks Technologies said.

Comprehensive and quality answer.

Should be stickied for BR builds.

Only thing id add is you can get away with an 8 twist no problems.

 

[smoothy8500]

just wait for an fclass/bench shooter to see more tips on this discipline in particular

You'll have to pick one direction or another (PRS/f-class) and accept a certain compromise. I shoot f-class but dabble in PRS and have found that a PRS rifle set-up can do ok in f-class, but an f-class rifle really can't perform in PRS.

The 6br is great, long barrel life, low recoil, super easy to find a good load/seating depth. As for muzzle brakes "prohibited" in f-class, that's true per the rules. But most clubs will still allow you to shoot but won't turn in the score to the NRA. Most club matches have a wide mix of rifles and disciplines on the line. Everything from full on f-class, PRS, tactical, to a hunting rifle with a cheap bipod.

 

[Dale264]

Load up 30 grains of Varget (or equivalent grains of n150 or other such stuff) with a Berger 105, 108, or 109. Or hornady 108. Whatever you can find.

Not to be the reloading police but....

30gr was touch too hot for this guy. 29.8-29.9 was the ticket since im running a slighty shorter freebore.

 

[Feniks Technologies]

Not to be the reloading police but....

30gr was touch too hot for this guy. 29.8-29.9 was the ticket since im running a slighty shorter freebore.

I’d be completely shocked to see 30.0 being any issue at all unless something like a tight bore barrel or something.

Freebore wouldn’t put 30.0 into non safe areas either.

Your situation is absolutely an anomaly with some issue such as soft brass or a tight bore.

 

[smoothy8500]

I dunno.....The conventional wisdom on 6mmBR/Accurateshooter is 30.0 gr Varget under any 105/106/108gr projectile.

 

[Ndbowhunter]

30gr varget and 103 eld-x or 108gr eld-m 10k into lands is too hot for my hunting rifle

 

[Ndbowhunter]

i still don't get why people are so horny for varget. it meters like shit, and it's slow

 

[Feniks Technologies]

30gr varget and 103 eld-x or 108gr eld-m 10k into lands is too hot for my hunting rifle

Into lands adds ~7k psi. As well as you likely have something else contributing.

 

[Ndbowhunter]

who knows. rl-15 tops out at 29.6

sierra didn't have dick for velocity or charge weights

 

[supercorndogs]

 

[RFutch]

Just finished a 6 BR build. I did a 24" for some damn reason and 200 rounds later I'm finding it's pretty slow. 30 gr Varget under a 105 hybrid gets me to 2793 fps. Not exactly what I was hoping for, wish I had gone with a longer barrel.

 

[BoilerUP]

2800ish from 24” seems within range of “normal”; I’ve got a 20” and its right at 2700fps with a 107SMK/108EH.

 

[kthomas]

Go with .237 bore over a .236 bore if you have the option.

A quality cut rifle barrel in 1:7.5-1:8 will shoot great. My rifle is a 1:7.5 twist 4-groove Krieger, and it's beyond precise. I don't think rifling type matters that much, a 5R probably shoots just as well.

If shooting H4895, 29.5 grains has been really good to me (6BRA FF loads with Lapua brass and 105 Bergers, which on first firing is a 6BR).

 

[6brshooter]

I've found I get better speed with a .236 bore, over .237. Now that could be the individual barrels, but after 6+ .236 and 4+ .237, that's my call. I prefer h4895 in 6br, 308, and 223 over varget, I get more speed. 29.5-29.8gr h4895 with 105 hybrids will get 2880-2920 in 26" .236" bore. I get 2690-2730 in a couple 18" 6br's with 105hybrids or 107smk.

 

[kthomas]

I've found I get better speed with a .236 bore, over .237. Now that could be the individual barrels, but after 6+ .236 and 4+ .237, that's my call. I prefer h4895 in 6br, 308, and 223 over varget, I get more speed. 29.5-29.8gr h4895 with 105 hybrids will get 2880-2920 in 26" .236" bore. I get 2690-2730 in a couple 18" 6br's with 105hybrids or 107smk.

I've only ran .237 bores, so appreciate your feedback.

I've read of potential issues of tighter bores in the 6mm, but perhaps they don't really manifest in the 6BR.

 

[Feniks Technologies]

Smaller bore = more resistance = more pressure = more velocity

It’s no problem if it doesn’t pressure you out. But at times a .236 is the culprit on pressure issues.

 

[6brshooter]

Those points do make sense, but I've saw better speed out of 243ai, 243 and 6creed with .236. Those were 8tw .236 prefits from criterion, cheap option on barrel burner cartridges. I know when I got into 6br 14yrs ago, a tech at Sinclair and bruno's suggested .236 for factory bullets and .237 if I was using custom bullets. This was for short range br. They opined that the custom bullets were more true to size, whereas factory bullets were a bit undersized. I used 66gr Bart Sauter hammerheads, and got along great. I've tried .237 in bart and brux, they shot fantastic but so did my criterion and gave more speed. My experience is a small sample, I'm sure Frank Green or Speedy Gonzalez would have more data points to prove/disprove my experience.

 

[kthomas]

Those points do make sense, but I've saw better speed out of 243ai, 243 and 6creed with .236. Those were 8tw .236 prefits from criterion, cheap option on barrel burner cartridges. I know when I got into 6br 14yrs ago, a tech at Sinclair and bruno's suggested .236 for factory bullets and .237 if I was using custom bullets. This was for short range br. They opined that the custom bullets were more true to size, whereas factory bullets were a bit undersized. I used 66gr Bart Sauter hammerheads, and got along great. I've tried .237 in bart and brux, they shot fantastic but so did my criterion and gave more speed. My experience is a small sample, I'm sure Frank Green or Speedy Gonzalez would have more data points to prove/disprove my experience.

I guess we may as well tag in @Frank Green to get his thoughts to see if bore size really matters or should be a consideration for the OP.

 

[6brshooter]

I've read Mr Green's opinion, I know he prefers .237, and I respect that. I like his barrels quite a bit, but I can't quite discount what I've saw over what I read online. I guess the other thing is, the criterion are button rifled and they say .236. I've never measured one, so there is that variable. Lol, I'm a lot of help.

 

[Frank Green]

I guess we may as well tag in @Frank Green to get his thoughts to see if bore size really matters or should be a consideration for the OP.

Tag I'm it! Here is some reading material for you guys.

Whenever you tighten up the bore dimensions/bore and groove or a combination of both...typically what happens is pressures and velocities go up. Velocity going up sounds cool and I like velocity at times as much as the next guy but keep in mind the pressure typically goes up. You might say...well I don't have hard bolt lift etc...doesn't matter...it's there. I want my gun to work in all temps and all conditions. Not just at 75F. I want it to work when it's a 100F for temp as well.

I've seen ammunition pressure test barrels where the bore and groove where a .0005" undersize on each and it drove up pressures 10k psi. Yes velocity went up like +150fps.

So keep that in mind...as the gun will and your components like your brass etc...will take more of a beating.

In terms of accuracy overall...there is no difference with the bore size with good quality bullets. This has been proven over and over again.

If you want to talk nitty gritty on accuracy....the short range benchrest guys shooting 6PPC.... way more of those matches have been won with the .237" bore barrels vs a .236" bore. They've noticed that they are more consistent/forgiving call it what you want. Yes and I mean no offense here that the BR guys are kind of psycho on the accuracy side of things. A guy wanting groups to be in the flat .200's or smaller vs a guy with a accuracy requirement of .500 is a big difference and the .5" guy probably won't make a hill of beans difference to.

What I don't like about the .236" bore barrels and this is from personal experience (as I use to shoot exclusively .236" bore barrels in 4 groove barrels years ago) is that the tighter bore / the rifling will cut deeper into the bullet jackets. This can and will increase bullet failure. It's happened to me and I proved it was a combination of the bullets having issues and the .236" bore just made it worse.

If a customer insists on wanting a .236" bore barrel and he says in a 4 groove I'll warn him that it will work against him sooner rather than later. Then I really try and insist that he gets the 5R rifling. The odd number of lands and grooves will help in distorting/upsetting the bullet jacket less than a even groove barrel will. This does not take away the pressure going up though.

Also thru testing with a ammo/bullet maker as well as one of the gov't testing facilities....testing was not coordinated between the two places and was done at random and the ammo place did it by accident. Both places data shows the 5R rifling also helped the flight of the bullet. I just talked to one of the places a week ago and this came up and they told me the same thing.

My stance is this...shooting good quality match bullets/ammo...a tight bore isn't doing anything extra for you.

Now if your shooting poorer quality bullets or bullets that are dimensionally undersize for a given caliber....then I can see the merit's of running a tight bore barrel.

We just made a ammunition test barrel at no charge and it shipped today to the ammo maker for testing. The thing behind it is a company gave it they're coating/metal treatment as they are saying it helps barrel life. One of the ammunition companies will be doing all the testing at no charge. We will see what happens. The side thing of this is after the barrel got treated the bore is .0001" undersize and the grooves tightened up right to min spec. of .0000". Will see what that does to any pressure issues on the ammo. Not all ammo/calibers are equal. I know the 300WM MK248MOD0 ammo runs hot/higher pressure than normal. A bore at size or just under makes the pressure jump even more. If those test barrels are at or just under the min. spec. they will not use them!

Later, Frank
Bartlein Barrels

 

[brianf]

^^^^
@Frank Green

can we save this for next month when someone who has a wobbly lathe in their basement who shoots PRS comes out and starts a thread saying the exact opposite

copy and paste will save a lot of bandwidth on the site, and a lot of Frank G's time typing...when he could be making barrels lol


just a idea

 

[Average guy]

^^^^
@Frank Green

can we save this for next month when someone who has a wobbly lathe in their basement who shoots PRS comes out and starts a thread saying the exact opposite

copy and paste will save a lot of bandwidth on the site, and a lot of Frank G's time typing...when he could be making barrels lol


just a idea

Since when are you worried about bandwidth on here. That’s rich. How many pages was the thread that ultimately got locked. I think you were involved with that.

 

[iceng]

 

[brianf]

Since when are you worried about bandwidth on here. That’s rich. How many pages was the thread that ultimately got locked. I think you were involved with that.

Read between the lines…

A reputable source stated fact.

I only suggested “bandwidth”, as to not insult future idiotic posts about the same topic which are a complete 180 from the above.

Additionally the thread got locked for the same reason..people with no knowledge were speaking like certain events were true.

So I’m fact….I’m the one who has absolute knowledge of bandwidth waste.

 

[Average guy]

Not disputing Frank Green one bit. All the rest of your dribble is just that.

Great thing about this site is folks who have a lathe in their garage can post their findings. It’s pretty rich after launching a company on this site , you bag on others who are potentially discovering their next big thing.

 

[brianf]

Unless I’m missing it, this thread started looking for advice on a build not the creation of a product or the next big thing.

Advice was given by the exact barrel maker of his choice.

Not sure what the problem is but let’s not derail a thread.

 

[Average guy]

Nice out

 

[Frank Green]

We just made a ammunition test barrel at no charge and it shipped today to the ammo maker for testing. The thing behind it is a company gave it they're coating/metal treatment as they are saying it helps barrel life. One of the ammunition companies will be doing all the testing at no charge. We will see what happens. The side thing of this is after the barrel got treated the bore is .0001" undersize and the grooves tightened up right to min spec. of .0000". Will see what that does to any pressure issues on the ammo. Not all ammo/calibers are equal. I know the 300WM MK248MOD0 ammo runs hot/higher pressure than normal. A bore at size or just under makes the pressure jump even more. If those test barrels are at or just under the min. spec. they will not use them!

Later, Frank
Bartlein Barrels

To update my last paragraph above....

The treated barrel with the bore .0001" undersize and the groove being right at .0000".... and I quote from the ammo maker doing the testing...

"In that first 50 rounds fired thru it a sample lot for pressure and velocity they used 5 rounds of production ammo that in a standard barrel with no coating gave them a velocity of 2690fps and a pressure of 57k psi. but the same lot of ammo fired thru the treated barrel gave them 2803fps and 66k psi. So a pressure jump of 9k psi and a velocity jump of 113fps."

Later, Frank

 

[kthomas]

@Frank Green

On another forum there is rumors going around that ammo companies have found that cut rifled barrels have longer barrel life than buttoned barrels in their test barrels.

Any truth to this?

 

[308pirate]

30gr varget and 103 eld-x or 108gr eld-m 10k into lands is too hot for my hunting rifle

 

[Frank Green]

@Frank Green

On another forum there is rumors going around that ammo companies have found that cut rifled barrels have longer barrel life than buttoned barrels in their test barrels.

Any truth to this?

Yes and not just me saying it either. All data we've gotten back from bullet and ammo makers have confirmed that. It's not to say you cannot have a button or hammer forged barrel go along time or just as long but not the norm.

One bullet maker/ammo maker when I first asked this question years ago.... that when they tested specific 30cal bullets for a very specific test I asked the question.....I know you have used BRAND XYZ button rifled barrels along with ours. What do you see in barrel life difference if any between the two? I was told at a minimum the cut rifled barrels went 15% longer. I would always say 25% longer but lets stay with 15% for now.

Even at 15% you start adding up the round count on a given caliber. On a 308w if you get 10k rounds out of the barrel...now your adding another 1500 rounds of barrel life to it. If it's a caliber that you only get 1200 rounds out of it normally that's another 180 rounds. That 180 rounds you can use it as load development, testing a scope, putting a zero on the rifle etc.. and your not taking that 100+ rounds off of your barrel life do that if you follow me. Let alone maybe getting another match or two out of the barrel. Or think of it this way....if you only have to buy 4 barrels to shoot the rifle season with vs. buying 5 or 6 barrels...your saving some money on buying less barrels along with the gunsmithing costs as well.

Later, Frank

 

[kthomas]

Yes and not just me saying it either. All data we've gotten back from bullet and ammo makers have confirmed that. It's not to say you cannot have a button or hammer forged barrel go along time or just as long but not the norm.

One bullet maker/ammo maker when I first asked this question years ago.... that when they tested specific 30cal bullets for a very specific test I asked the question.....I know you have used BRAND XYZ button rifled barrels along with ours. What do you see in barrel life difference in any between the two? I was told at a minimum the cut rifled barrels went 15% longer. I would always say 25% longer but lets stay with 15% for now.

Even at 15% you start adding up the round count on a given caliber. On a 308w if you get 10k rounds out of the barrel...now your adding another 1500 rounds of barrel life to it. If it's a caliber that you only get 1200 rounds out of it normally that's another 180 rounds. That 180 rounds you can use it as load development, testing a scope, putting a zero on the rifle etc.. and your not taking that 100+ rounds off of your barrel life do that if you follow me. Let alone maybe getting another match or two out of the barrel. Or think of it this way....if you only have to buy 4 barrels to shoot the rifle season with vs. buying 5 or 6 barrels...your saving some money on buying less barrels along with the gunsmithing costs as well.

Later, Frank

As always, appreciate the detailed and knowledgeable response!

 

[Frank Green]

As always, appreciate the detailed and knowledgeable response!

That test they did wasn't just based on one cut rifled barrel and one button barrel. It was based multiples over the course of several years.

Everyone reading this you also need to keep this in the back of your mind as well......

When you hear...oh I had this barrel from brand X and it out lasted my buddies barrel made by brand Z! Ask these questions....

Same chamber reamer spec used?

Shot at the same rate of fire?

Same lot of ammo or should I say the same lot of components used to load the ammo..not just bullets but powder and primers and cases.

Cleaned at the same intervals with the same cleaning procedure?

Shot in controlled/same conditions?

What are the bore and groove dimensions measured to the 4th decimal place (so .XXXX").

Did the barrel blank come from the same lot of steel?

You change any of the above items I just listed...you are not comparing apples to apples and not coming to a scientific conclusion with consistent data.

Later, Frank

 

[308pirate]

Yes and not just me saying it either. All data we've gotten back from bullet and ammo makers have confirmed that.

Do we understand the reason(s) why? I'm always much more interested in the why than in the what.

 

[Frank Green]

Do we understand the reason(s) why? I'm always much more interested in the why than in the what.

For one is button rifling and hammer forge rifling work hardens the bore. Single point cut rifling does not do this. So when you start to lose those little chunks of edges off of the lands due to wear is one reason your accuracy starts to puke. Button rifling I’ll say it typically happens sooner rather than later.

Work hardening of the bore contrary to what some think…does not help barrel life.

Button rifling displaces the material. Like a snake swallowing a mouse. So for instance on a 30cal barrel and lets assume the spec is .300 x .308 bore and groove…you might have to pull a .312” diameter button thru the bore to get to those numbers. The steel will expand and relax. Pull or push the button thru in say a minute or so and you have your rifled blank.

Cut rifling physically cuts the grooves. We don’t touch the tops of the lands (bore) during rifling. We are also only typically cutting out about .0001” to .00015” per pass one groove at a time.

After button rifling and if your a good button barrel maker you have to take the blank (no contour on the barrel) and the blank needs to go into a oven and get stress relieved. No guarantee all the stress gets taken out either.

Single point cut rifling because no stress is induced into the steel does not need to be restress relieved after rifling.

Old PJ Hart button rifled barrels and Obermeyer cut rifled barrels use to talk as Boots had told me years ago. Even when the steel was melted at Crucible and both places got they’re steel out of the same lot….they noticed that Boots barrels cut rifled barrels would typically outlast the button barrels.

I won‘t even get into uniformity of the twist and groove sizes….this advantage goes to cut rifling as well.

Later, Frank

 

[308pirate]

For one is button rifling and hammer forge rifling work hardens the bore. Single point cut rifling does not do this. So when you start to lose those little chunks of edges off of the lands due to wear is one reason your accuracy starts to puke. Button rifling I’ll say it typically happens sooner rather than later.

I'm thinking that metallurgically is the key. Hardness without temper = brittleness.

Add flame cutting and you know the rest.

 

[Frank Green]

I'm thinking that metallurgically is the key. Hardness without temper = brittleness.

Add flame cutting and you know the rest.

Old PJ Hart button rifled barrels and Obermeyer cut rifled barrels use to talk as Boots had told me years ago. Even when the steel was melted at Crucible and both places got they’re steel out of the same lot….they noticed that Boots barrels cut rifled barrels would typically outlast the button barrels.

My quote above for a previous post....even when the steel came out of the same lot....so let's rule out metallurgical issues....Obermeyer and Hart seen differences in barrel life.

Yes the flame temperature, pressure etc...doesn't help anything.

Flame temperature at the throat of the chamber depending on caliber and powder etc...if I recall correctly is between 2200f and 4000f. Yes it only happens for milliseconds but think of it this way.... 2200f is like the temperature of lava.

 

[308pirate]

Old PJ Hart button rifled barrels and Obermeyer cut rifled barrels use to talk as Boots had told me years ago. Even when the steel was melted at Crucible and both places got they’re steel out of the same lot….they noticed that Boots barrels cut rifled barrels would typically outlast the button barrels.

My quote above for a previous post....even when the steel came out of the same lot....so let's rule out metallurgical issues....Obermeyer and Hart seen differences in barrel life.

Take two steel samples from the same heat/lot. Subject one to work hardening and the other one not. The metallurgy of the work hardened one has been changed, even though both are the same chemical composition.

Work hardening without subsequent tempering or annealing will leave a brittle region that should be much more susceptible to heat checking. That is what I am beginning to think explains the durability of cut rifled barrel, which don't work harden the surface as much (if at all).

Thermal stress relieving doesn't alleviate the embrittlement from work hardening. Either need to anneal or freeze/temper.

Sorry if I wasn't clearer.

 

[Frank Green]

Take two steel samples from the same heat/lot. Subject one to work hardening and the other one not. The metallurgy of the work hardened one has been changed, even though both are the same chemical composition.

Work hardening without subsequent tempering or annealing will leave a brittle region that should be much more susceptible to heat checking. That is what I am beginning to think explains the durability of cut rifled barrel, which don't work harden the surface as much (if at all).

Thermal stress relieving doesn't alleviate the embrittlement from work hardening. Either need to anneal or freeze/temper.

Sorry if I wasn't clearer.

Yep we are on the same page. I wasn't reading your post correctly or didn't understand it correctly. Sorry for any confusion.

 

[beetroot]

I've always wondered what the tooling/process is for cutting rifling.
I assume it's done using a broach/broaching?