Interesting Video on Fitting a Mauser Barrel

[Willbird]

Well there is that.....
LOL!

I think everybody that has decided on ways to get it done, struggled some with finding what seemed right to them.

I know two smiths who are 180 degree opposite about whether to fit a rem bolt nose .001 fit to the barrel counterbore, I listed to both, but the one guy told me he does not want the bolt nose touching anything ANYWHERE, and it rung true with me and I now use .01 in every direction to make sure it never does.

Reading through Rifle Accuracy Facts by Dr. Harold Vaughn taught me a LOT....has me going NO NO NO when people talk about stiffening up receivers with beefy scope mounts screwed on top. Saw it in reference to a Muzzle loader build on a savage action and reasoning told me "the reciever ring is not in tension when it fires, no issue there".

Anybody that can find a copy of that book is encouraged to read it from cover to cover.

Bill

[MBTcustom]

I think everybody that has decided on ways to get it done, struggled some with finding what seemed right to them.

I know two smiths who are 180 degree opposite about whether to fit a rem bolt nose .001 fit to the barrel counterbore, I listed to both, but the one guy told me he does not want the bolt nose touching anything ANYWHERE, and it rung true with me and I now use .01 in every direction to make sure it never does.

Reading through Rifle Accuracy Facts by Dr. Harold Vaughn taught me a LOT....has me going NO NO NO when people talk about stiffening up receivers with beefy scope mounts screwed on top. Saw it in reference to a Muzzle loader build on a savage action and reasoning told me "the reciever ring is not in tension when it fires, no issue there".

Anybody that can find a copy of that book is encouraged to read it from cover to cover.

Bill

Well that's just common sense! LOL!
Gunsmithing reminds me of a story that was told to me by a friend of mine who runs a sawmill.
He told me that at one time, it was commonly held that if a nut bearing tree wasn't producing, it was because of a lack of iron, so they would pound nails in the trunk of the tree to fix its iron deficiency. The tree would respond by bearing much more fruit, which reinforced the commonly held position. Then comes along the scientists and master foresters who explained that the tree didn't need iron at all! It just needed to be stressed. It thought it was mortally wounded, so it tried to reproduce itself in response to the nails that had been pounded into it's trunk.

Sometimes I think we get the right result, but without a real understanding of why.

[Willbird]

Well that's just common sense! LOL!
Gunsmithing reminds me of a story that was told to me by a friend of mine who runs a sawmill.
He told me that at one time, it was commonly held that if a nut bearing tree wasn't producing, it was because of a lack of iron, so they would pound nails in the trunk of the tree to fix its iron deficiency. The tree would respond by bearing much more fruit, which reinforced the commonly held position. Then comes along the scientists and master foresters who explained that the tree didn't need iron at all! It just needed to be stressed. It thought it was mortally wounded, so it tried to reproduce itself in response to the nails that had been pounded into it's trunk.

Sometimes I think we get the right result, but without a real understanding of why.

Well the one guy loves the idea of the bolt nose riding in the c'bore...after some thought I disagree .

The other guys told me how to bush a bolt which I have done a few of. Now we can just buy the PTG bolts if we wise made to fit.

Bill

[codgerville@zianet.com]

YES!! Willbird, you are right on with that. Before I retired they would bring some odd-shaped piece of worn-out junk in that had no common reference surfaces and was worn so bad there was no way to tell where the original bore had been and say, "we gotta have this by this afternoon." Fitting rifle barrels here in my home shop is relaxing compared to that. I might even take a break and have a mug of coffee and a pipe full of good tobacco.

[MBTcustom]

Well the one guy loves the idea of the bolt nose riding in the c'bore...after some thought I disagree .

The other guys told me how to bush a bolt which I have done a few of. Now we can just buy the PTG bolts if we wise made to fit.

Bill

You don't say?
In the same way, why blueprint a crappy M700 when you can buy a Stiller for cheaper?

[leftiye]

Well, at the risk of getting flamed all the way to the hot place, I gotta say this. Most of this doesn't matter. All praise to Mr Goodsteel's precision and in no way to offend, his setup is probly near perfect. But there are so many places that Mr gun does his act his way, as he desires, that it perhaps makes no difference. I'll start by saying "Yes, Why not do it perfectly? Precision can't hurt." Then I'll say that where the last two inches of the barrel happens to be pointing at the moment the bullet passes through is what makes the difference.

Barrel harmonics for instance - the end of the barrel waving around in unfathomable patterns. Bedding for instance, the barrel moving in the stock. Causing the barrel to be in a different state of flex each time the barrel fires, not to mention pointing somewhere new each time. With today's bedding methods these can be miniscule, but I didn't start the worrying about miniscule here. Action bedding, same story. Action internal stresses built in during production. Scope mounting imperfections, etc. Bullet imperfections. Powder not burning precisely right, nor the same each time. Cases varying in concentricity, and volume. Case neck concentricity. Primer variances. Bore condition changing as firing goes on. Ambient temperature changes, etc.

There's so much else going on after the boo/ullet enters the rifling. Plus that entry depends more on the correct (optimum) dimensions of bore, rifling, freebore, and leade than the precise dimensions of these and the chamber itself further back. Coaxiality of chamber does matter, but tenths of thousandths probly don't.

Exactly how a reamer cuts the chamber is dependent on what? Whether the last two or three inches of barrel are straight. Whether they turn parallel and concentric to the axis of? Of the reamer! Runout of barrel while cutting Should be minimized, But how much runout can happen before it affects a free floating reamer?

This not in any way to advocate sloppy practices, non attention to precision, or any of that. Only to say that you can have a perfect rifle and have one that doesn't shoot perfect one hole groups which are groove diameter.

[tek4260]

Great point! Has anyone ever been able to determine how much a barrel "whips" when you fire it? I know they are all different, but has anyone been able to measure one in particular?

[MBTcustom]

Great point! Has anyone ever been able to determine how much a barrel "whips" when you fire it? I know they are all different, but has anyone been able to measure one in particular?

Near as I can tell, the guy that designed the quickload program did tests that seemed to support his theories. (My own experience seems to lend merit to his theories as well, but I might just be hammering nails into trees LOL!).
I have seen high speed camera footage that seems to clearly show the barrel whip, but that's not an exact measurement either.

I think the most research has been done on the effect of the barrel harmonics (BTW, there are two distinctly different kinds of harmonics that effect the barrel when the trigger is pulled) rather than the physical changes that take place, but I'm sure someone found a clever way to get an exact figure.

I can tell you who I would ask though. Maybe Larry Gibson, or Felix will weigh in here. I'd just bet they can speak more intelligently than me on that subject.

[fouronesix]

Great point! Has anyone ever been able to determine how much a barrel "whips" when you fire it? I know they are all different, but has anyone been able to measure one in particular?

Yes, it's been done within the instrumentation capabilities available including the lateral movement and the on-axis compression waves within the barrel/action. Ends up being far too complex to model predictions about "accuracy on target" outcome though- as leftiye pointed out. Just put rifle and ammo together within the best tolerances that can be done, then see what the target shows. Well known generalities usually apply- but the prediction of results is where most "models" have shortcomings. That's why testing and verification still exists.

[Willbird]

You don't say?
In the same way, why blueprint a crappy M700 when you can buy a Stiller for cheaper?

Well one can go to Maomart and buy a 700 rifle in a popular caliber, pull the barrel and stock and sell them, and if you were to use a PTG bolt sell the orig bolt as well, and maybe have $0 in the action at that time.

Plus I just like 700's, always have. When I trued mine and bushed the bolts I had $0 in all 3 at that point.

Bill

[Willbird]

Yes, it's been done within the instrumentation capabilities available including the lateral movement and the on-axis compression waves within the barrel/action. Ends up being far too complex to model predictions about "accuracy on target" outcome though- as leftiye pointed out. Just put rifle and ammo together within the best tolerances that can be done, then see what the target shows. Well known generalities usually apply- but the prediction of results is where most "models" have shortcomings. That's why testing and verification still exists.

Dr. Harold Vaughn put accelerometers on a rifle barrel then fired the rifle, and documented the results in a scientific fashion in the book "Rifle Accuracy facts"...he did many other scientific things with bullets, barrels, and actions as well.

[Willbird]

Dr. Harold Vaughn put accelerometers on a rifle barrel then fired the rifle, and documented the results in a scientific fashion in the book "Rifle Accuracy facts"...he did many other scientific things with bullets, barrels, and actions as well.

He actually isolated some of the "whips" down to assymetry in the rifle action, one was caused by the gas port drilled in one side, the solution there was to drill a matching gas port in the other side of the action. And the most interesting was that a scope base that stiffened the action caused ANOTHER asymmetry, the cure there was to make a base that did not stiffen the action....many people think stiffening the top of an action with a big beefy one piece "moa" type base would be a GOOD thing, and in fact the reverse is true IMHO and Dr. Vaughns Scientific opinion too.

[leftiye]

Great point! Has anyone ever been able to determine how much a barrel "whips" when you fire it? I know they are all different, but has anyone been able to measure one in particular?

Way back, I heard that to get a 1" (100 yards) group you only need .001" variance in muzzle position. More lately, others have calculated other outcomes, but group size it would seem is a tell tale as to what the barrel is doing. There may be some effect at release from the muzzle (launch), that now, is truly uncalculable.