Barrel to action torque?

[Joefrazell]

Ok so I've got a rem 700 with a bartlein barrel that I had a gunsmith chamber and install. Also had a mbm muzzle brake installed. When I got the rifle back I noticed the brake was pretty loose. I was able to take it off with very little force with my hand. Anyways I know it would come loose under recoil so I grabbed a old inner tube and cut a good strip off and wrapped it around the brake several times and used a 10" pair of channel locks to snug it down. I'm a mechanic by trade and typically know how tight to get things by feel. It was snug but definitely not too tight. Okay so fast forward a month or so. Been having accuracy issues and trying to narrow down the problem I thought it would be a good idea to remove the brake and see if accuracy increases. So grab the inner tube and channel locks and start turning. I held the stock in one hand and the channels in the other and applied some pressure and the next thing I know the barrel is loose from the action. I was very surprised that this happened. If I had to put a torque value on it I'd say maybe 10 ft lbs max. It was not very tight. Now from what I've researched is they should be anywhere from 40 ft lbs to 100 or more. Would the lack of torque be my accuracy issue? I've got a call into my Smith and am waiting for a call back.

 

[birdiemc]

Speaking as a mechanic here, cuz I'm not a gunsmith, but torque specs are there to allow us to get things tight enough that they dont back off on their own, but not so tight that it puts undue street in the materials. The specs are based on material size and composition and threads.
So from my perspective, from the way I read your post, as long as the barrel was tight and not wobbling it shouldn't have any effect on accuracy.
But....a gunsmith who doesn't know how to torque a brake and a barrel might have made some other errors.

 

[J E Custom]

35 to 40 ft/lbs is minimum and 65 to 70 is maximum in my opinion. I use a thread lubricant that reduces torque requirements but reaches the same compression on the receiver. after testing the torque without any lubricant and then with, the torque came to 57 ft/lbs and is very repeatable if the barrel has to come off at a later date.

Some bench rest shooters tighten there barrels hand tight, but they must keep a constant watch on the barrel (They do this to minimize any stress).

Consistent torque is very important to maintain perfect head space and stresses.

J E CUSTOM

 

[Hawkeye Pierce]

I also was a mechanic and know a little bit about gunsmithing. When you torque the barrel it pulls in a straight line away from the action. If you're not getting enough torque, it won't be inline hence accuracy issues. I would call whoever made the action and barrel if you can't get hold of your smith to find specs.

 

[birdiemc]

I also was a mechanic and know a little bit about gunsmithing. When you torque the barrel it pulls in a straight line away from the action. If you're not getting enough torque, it won't be inline hence accuracy issues. I would call whoever made the action and barrel if you can't get hold of your smith to find specs.

Please help me understand this...I never took physics, just try to learn on my own

I always just assumed the square shoulder on the barrel good and tight against the recoil lug, in this case, is what held everything in alignment.

 

[Joefrazell]

Please help me understand this...I never took physics, just try to learn on my own

I always just assumed the square shoulder on the barrel good and tight against the recoil lug, in this case, is what held everything in alignment.

Basically, if there were a slight high spot or burr on any of the surfaces and it was only snug it could throw off the concentricity. But if it were torqued down it would force it into being strait. That's how I'm understanding it anyways.

The barrel was definitely not loose but definitely not anywhere near as tight as I'd expect it to be. Don't really think it's my accuracy issue though. He will get it figured out I'm sure.

 

[Hawkeye Pierce]

Please help me understand this...I never took physics, just try to learn on my own

I always just assumed the square shoulder on the barrel good and tight against the recoil lug, in this case, is what held everything in alignment.

True but like joe said its about uniformity, when you torque it, it pulls against the threads and forces the face square if it is so.

 

[Joefrazell]

So far I've tried swapping the scope, rings, base and the stock. All with quality products and to no avail. Also have tried shooting off of 3 different platforms. Front and rear bag, hunting pack and rear bag and bipod and rear bag. I've tried 3 different bullets and 3 powders. With a bartlein barrel I really don't think it should be that difficult to find a quality load. Ive got 175ish down the pipe and have no load that will even hold moa consistently.

 

[shortgrass]

The barrel, with an 1 1/16-16T.P.I. thread, needs to be torqued to between 55 and 60 ft lbs. ,,, I have always found that to be "tight enough". This should cure your problem, but maybe not. If your "smith" only torqued to 10-15 ft lbs, and you could unscrew it by hand, it wasn't
tight enough to keep the barrel from loosening from the receiver from use. That begs the question, what else might have been overlooked? Was the face of the action cut square? Is the recoil lug (Rem calls it a barrel bracket) surface ground on both sides? After the barrel is properly torqued, the head space should be checked again. This is just another "hard to know" problem without having rifle in hand. I have used numerous Bartlein barrels and never had an issue with any of them.

 

[Joefrazell]

Action was supposed to be tried. I don't know how to check to see if it was though. The recoil lug is an aftermarket trued lug

 

[shortgrass]

Then I'd have the barrel properly torqued to the action, check the head space again, and see what happens!

 

[WildRose]

True but like joe said its about uniformity, when you torque it, it pulls against the threads and forces the face square if it is so.

No, I think that is a great way to induce errors. When you force two things together that are not perfectly square and true soemthing has to give and that screws up the centerline of the bore and will likely push the action somewhat out of square.

 

[WildRose]

Action was supposed to be tried. I don't know how to check to see if it was though. The recoil lug is an aftermarket trued lug

Joe I'd get a proper strap wrench and torque it to spec. Just use a little locktite on the threads of the break, let it dry, then screw it on. That should keep it from walking on you.

 

[WildRose]

So far I've tried swapping the scope, rings, base and the stock. All with quality products and to no avail. Also have tried shooting off of 3 different platforms. Front and rear bag, hunting pack and rear bag and bipod and rear bag. I've tried 3 different bullets and 3 powders. With a bartlein barrel I really don't think it should be that difficult to find a quality load. Ive got 175ish down the pipe and have no load that will even hold moa consistently.

Might be time to have a talk with Bartlien and maybe take it back to the smith who trued and screwed it all together.