Barrel set back

[RetiredArmy]

This is not my gun, buddy of mine bought it new a few years ago. Factory savage 12 fclass. I have no idea where the head space was set from the factory. Called me on tues and told me that brass had separated. Asked if he could borrow my gauges.
Called and said bolt closed on no-go gauge. Fast foward to today, have found out he was shooting 105 amax, 30gr varget, what ever his coal was. Started shooting 107 smk never changed powder charge or coal. Sooo, things are starting to make a little more sence now. I understand head space and how to set up my dies, again this is not mine and I took it for granted that he new better. With all that being said, it it even possible for the head space on a rifle to change with out physically moving the barrel?
P.S before this started happening, he said it shot well.

 

[MikeMcCasland]

This is not my gun, buddy of mine bought it new a few years ago. Factory savage 12 fclass. I have no idea where the head space was set from the factory. Called me on tues and told me that brass had separated. Asked if he could borrow my gauges.
Called and said bolt closed on no-go gauge. Fast foward to today, have found out he was shooting 105 amax, 30gr varget, what ever his coal was. Started shooting 107 smk never changed powder charge or coal. Sooo, things are starting to make a little more sence now. I understand head space and how to set up my dies, again this is not mine and I took it for granted that he new better. With all that being said, it it even possible for the head space on a rifle to change with out physically moving the barrel?
P.S before this started happening, he said it shot well.

No, it's not possible for the rifle headspace to change without loosening the nut and moving the barrel (major changes), or swapping bolts/bolt heads (minor changes) on a Savage.

 

[RetiredArmy]

No, it's not possible for the rifle headspace to change without loosening the nut and moving the barrel (major changes), or swapping bolts/bolt heads (minor changes) on a Savage.

Thank you Mike, will have him bring his brass, dies, ect to my house this weekend and go from there.
Thanks Bill

 

[Ggmac]

Make sure he wasn't forcing the no go gauge . I've seen some unbelievable force used .

 

[gunsandgunsmithing]

You can adjust headspace as far as bolt to barrel clearance will allow. If you can close the bolt on a go gage with the barrel just off of the barrel, there is a chamber or bolt issue. I chamber them for bolt closure on a go gage(zero hs) and .005 clearance between the bolt nose and the end of the barrel.
With a Savage, you have a little bit more wiggle room in terms of unsupported case than with a Remington, for example.
Proper bolt clearance is an important safety factor and should never, ever be discounted. You can have .100+ excess headspace and simply fire form a case with more capacity but if a case ever separates, bolt clearance is what stands between you and a face full of brass and gas. That clearance is a critical dimension!

If that barrel has 4500 rounds on it, he got his money's worth and then some...It's time for a properly setup new barrel, anyway. There is something wrong if he was having cases separate with one firing on new brass. Any good gunsmith can get to the bottom of the problem in a few minutes if it is a hs and/or barrel fitment issue. There is the very slim possibility of bad, new brass...but extremely unlikely. Savage has less unsupported brass than most others so it's a little more forgiving than some but diagnosing and verifying PROPER clearance and hs is the primary reason I'm not a fan of any prefits. IMO, it's only a DIY job for anyone that wholeheartedly understands and has the means to check what I've just touched on here. JMHO.--Mike

 

[RetiredArmy]

You can adjust headspace as far as bolt to barrel clearance will allow. If you can close the bolt on a go gage with the barrel just off of the barrel, there is a chamber or bolt issue. I chamber them for bolt closure on a go gage(zero hs) and .005 clearance between the bolt nose and the end of the barrel.
With a Savage, you have a little bit more wiggle room in terms of unsupported case than with a Remington, for example.
Proper bolt clearance is an important safety factor and should never, ever be discounted. You can have .100+ excess headspace and simply fire form a case with more capacity but if a case ever separates, bolt clearance is what stands between you and a face full of brass and gas. That clearance is a critical dimension!

If that barrel has 4500 rounds on it, he got his money's worth and then some...It's time for a properly setup new barrel, anyway. There is something wrong if he was having cases separate with one firing on new brass. Any good gunsmith can get to the bottom of the problem in a few minutes if it is a hs and/or barrel fitment issue. There is the very slim possibility of bad, new brass...but extremely unlikely. Savage has less unsupported brass than most others so it's a little more forgiving than some but diagnosing and verifying PROPER clearance and hs is the primary reason I'm not a fan of any prefits. IMO, it's only a DIY job for anyone that wholeheartedly understands and has the means to check what I've just touched on here. JMHO.--Mike

Mike,
The only thing that has changed since the rifle was built at the factory, is he switched from 105 amax to 107 smk. EVERYthing stayed the same except the bullet. Powder charge, coal everything just like the 105 amax. Even with 4500 rounds fired I've been told the head space can not change. So with that being said, If new load work up was done and his dies were set correctly could this happen. If so how?
Thanks Bill

 

[gunsandgunsmithing]

Mike,
The only thing that has changed since the rifle was built at the factory, is he switched from 105 amax to 107 smk. EVERYthing stayed the same except the bullet. Powder charge, coal everything just like the 105 amax. Even with 4500 rounds fired I've been told the head space can not change. So with that being said, If new load work up was done and his dies were set correctly could this happen. If so how?
Thanks Bill

In a rh twist, I don't see any way. It makes my head hurt a little thinking about how a nut vs a shoulder may affect this but on the surface, I don't think it could.

 

[MislMan]

30 gr of Varget sounds like a stout load for 6BR. Might be a load issue since switching bullet brands and weight. How far into the lands with each bullet?

 

[RetiredArmy]

30 gr of Varget sounds like a stout load for 6BR. Might be a load issue since switching bullet brands and weight. How far into the lands with each bullet?

I'm not sure. He's one of those "every 6br should shoot 30gr varget at 2.xxx coal. Will sit down with him and his equipment and measure brass, dies, strip bolt to find lands with bullet (Wheeler way). Try to get him to understand starting load development with every new change. Was just trying to make sure it could not be a head space issue with the barrel. I'm not a gun smith just trying to wrap my head around this so maybe I can convince him it might be his loads.
Thanks Bill

 

[msinc]

Well, it sounds like it shot okay for a long time. Then he has case head separation and it closes on a no go...the only way I can see that and no one touched the barrel to receiver fit would be for the rifle to have had excessive headspace from day one and then it would have to have been shot with the bullet seated to touch the lands. Even that don't make sense though when you consider the round count....unless of course he was "chasing" the lands all along.
Did the gentlemen that has this rifle now have the distinction of firing all 4500 rounds down the pipe, or was this a deal where someone else allegedly did and sold him the rifle after the high round count and headspace has been adjusted {changed}????

 

[RetiredArmy]

Well, it sounds like it shot okay for a long time. Then he has case head separation and it closes on a no go...the only way I can see that and no one touched the barrel to receiver fit would be for the rifle to have had excessive headspace from day one and then it would have to have been shot with the bullet seated to touch the lands. Even that don't make sense though when you consider the round count....unless of course he was "chasing" the lands all along.
Did the gentlemen that has this rifle now have the distinction of firing all 4500 rounds down the pipe, or was this a deal where someone else allegedly did and sold him the rifle after the high round count and headspace has been adjusted {changed}????

As far as I know he bought it new. I will ask him and check with gauges myself on sat.
Thanks Bill

 

[dkhunt14]

Mike,
The only thing that has changed since the rifle was built at the factory, is he switched from 105 amax to 107 smk. EVERYthing stayed the same except the bullet. Powder charge, coal everything just like the 105 amax. Even with 4500 rounds fired I've been told the head space can not change. So with that being said, If new load work up was done and his dies were set correctly could this happen. If so how?
Thanks Bill

I believe the 107 Sierra has more bearing then a 105 Amax. The Amax is more of a vld type of bullet. If so, he is getting more pressure now. I think 30 grains of Varget is a stiff load in some guns. Matt

 

[d1686]

carbon ring

 

[Steve Ladino]

This is not my gun, buddy of mine bought it new a few years ago. Factory savage 12 fclass. I have no idea where the head space was set from the factory. Called me on tues and told me that brass had separated. Asked if he could borrow my gauges.
Called and said bolt closed on no-go gauge. Fast foward to today, have found out he was shooting 105 amax, 30gr varget, what ever his coal was. Started shooting 107 smk never changed powder charge or coal. Sooo, things are starting to make a little more sence now. I understand head space and how to set up my dies, again this is not mine and I took it for granted that he new better. With all that being said, it it even possible for the head space on a rifle to change with out physically moving the barrel?
P.S before this started happening, he said it shot well.

The barrel was originally fitted with excess headspace allowed, so it seems and reducing the HS now may put the back of the barrel to close to the bolt nose where you need about .010 " little less maybe , clearance.

 

[Texas10]

As far as I know he bought it new. I will ask him and check with gauges myself on sat.
Thanks Bill

When rechecking the headspace with your no-go gage, you can place successive layers of Scotch tape on the head of the no-go gage to get an idea just how far out of range the barrel is head spaced. If only two or three layers of tape result in a stiff bolt closure, you're not far out of the ball park and it definitely is not causing head separation. But if you put 10 layers on and the bolt closes normally, well, then you've got a serious problem. How the barrel got that way would be worth investigating.

One possibility I can think of right off the top is this: Is he absolutely sure he's using the right bolt and hasn't confused it with the bolt from another gun, maybe a 22-250 or 308? Stock bolt will have a serial number engraved on the bolt head.

Let us know how it goes.

 

[RetiredArmy]

When rechecking the headspace with your no-go gage, you can place successive layers of Scotch tape on the head of the no-go gage to get an idea just how far out of range the barrel is head spaced. If only two or three layers of tape result in a stiff bolt closure, you're not far out of the ball park and it definitely is not causing head separation. But if you put 10 layers on and the bolt closes normally, well, then you've got a serious problem. How the barrel got that way would be worth investigating.

One possibility I can think of right off the top is this: Is he absolutely sure he's using the right bolt and hasn't confused it with the bolt from another gun, maybe a 22-250 or 308? Stock bolt will have a serial number engraved on the bolt head.

Let us know how it goes.

I'll do it, he's supposed to be at my house in the am. I'm thinking it's the "one (same) load goes for everything" thinking that is the big problem.
Question- if it's not a head space problem, will a hot load, dies set wrong (setting shoulder back to far) bullet jammed cause brass to separate on the 2nd firing?
Thanks Bill

 

[MikeMcCasland]

I'll do it, he's supposed to be at my house in the am. I'm thinking it's the "one (same) load goes for everything" thinking that is the big problem.
Question- if it's not a head space problem, will a hot load, dies set wrong (setting shoulder back to far) bullet jammed cause brass to separate on the 2nd firing?
Thanks Bill

Sounds like it's a combination of multiple factors. We already know the bolt will close on a no-go gauge, so we know it's got too much headspace. It would also stand to reason that if he's got multiple 6BR rifles (I believe I read that earlier in the thread) that he's probably using one sizer for multiple rifles, so he may be bumping the shoulder at least .002 smaller than his shortest chamber. I.E. grossly over-sizing.

If you combine that with heightened pressures created by a large powder charge and/or hard jamming bullets, it could cause it. It could also just be some bad brass, but I've never had a bad lot from Lapua personally.

The whole ~4,500 rds thing still kinda throws a wrench into this. It's hard to imagine getting that far into a barrel and having problems. Someone did mention earlier, a carbon ring is a potential cause too, but I would think it'd have to be one hell of a carbon ring.

 

[Texas10]

So you're saying this was only the second cycle on the brass that separated? Can you measure case head to shoulder on new vs once shot brass to see how much it's grown? And how much he's setting back the shoulder, it he is indeed setting back the shoulder?

What brass is he using?

 

[mikeeg02]

Some people full length size every time, but thats more common in hunting loads then competition loads. We strive to get 15+ firings on a case for competition use. A friend of mine this summer, who anneals the sh!t out of his 6br cases every firing in dasher configuration, and was setting them back ~.005" or .007" every time. He had case/head separation at ~14 firings. Quite a few at once. He no longer sets them back that far.

Separation on the second firing I believe is most likely a comination of a bad case, and an untested hot load.

30 grains of varget in a 6br is on the lower side of a pretty stout load with 105 class bullets. But earlier you said something important, and myself and I believe Matt caught it(maybe others too).

You kind of gave the impression this was an old load, with a new bullet, all else the same. The new bullet being a 107 smk vs the Amax. Starting at the same charge weight when at the high side, and going to a bullet with more bearing surface (or any bullet really) is IMO a reckless idea. If he switched bullets he should have started around 27.5-28 grains, and did a full work up.

In my opinion I think its a combination of a few things, a possible bad case, and hot untested load. If the headspace was way far off, then the area at the case where it may of blown out could have been unsupported by the barrel.

I would be curious to see both ends of the case that separated, to see if it truly just separated, or if it appears to be "blown out"

 

[RetiredArmy]

So you're saying this was only the second cycle on the brass that separated? Can you measure case head to shoulder on new vs once shot brass to see how much it's grown? And how much he's setting back the shoulder, it he is indeed setting back the shoulder?

What brass is he using?

That is the plan in the mornin, according to him yes 2nd firing. He's using Lapua.

Some people full length size every time, but thats more common in hunting loads then competition loads. We strive to get 15+ firings on a case for competition use. A friend of mine this summer, who anneals the sh!t out of his 6br cases every firing in dasher configuration, and was setting them back ~.005" or .007" every time. He had case/head separation at ~14 firings. Quite a few at once. He no longer sets them back that far.

Separation on the second firing I believe is most likely a comination of a bad case, and an untested hot load.

30 grains of varget in a 6br is on the lower side of a pretty stout load with 105 class bullets. But earlier you said something important, and myself and I believe Matt caught it(maybe others too).

You kind of gave the impression this was an old load, with a new bullet, all else the same. The new bullet being a 107 smk vs the Amax. Starting at the same charge weight when at the high side, and going to a bullet with more bearing surface (or any bullet really) is IMO a reckless idea. If he switched bullets he should have started around 27.5-28 grains, and did a full work up.

In my opinion I think its a combination of a few things, a possible bad case, and hot untested load. If the headspace was way far off, then the area at the case where it may of blown out could have been unsupported by the barrel.

I would be curious to see both ends of the case that separated, to see if it truly just separated, or if it appears to be "blown out"

Mike,
I didn't mean to leave an impression, more of a fact, old load data for 105 amax ONLY change is the bullet-107 smk.
Thanks Bill