Gunsmithing Threading barrel risk accuracy issues?

[rockchalk06]

Honest question and please excuse my ignorance here.

If a competent smith threads the barrel on my Savage, do I run the risk or loosing accuracy?

Barrel is 24" 1-10 factory and shot decent, but a happy accident today with some rounds I loaded in 2009 for a 700 LTR (FL Sized and 2.800" COAL), pulled off a 5 shot group that floored me. Plan was to sell the rifle, but now I'm thinking I'd like to run a break and eventually a can. Change out bottom metal for AICS pattern mags and keep it.

Thing is, I'm worried about accuracy loss. Never sent a rifle off to be threaded, I've always purchased them factory.

Thanks in advance SH

 

[XLR308]

You may have to retune the load after a brake is installed so long as the crown isn't damaged in the process I wouldn't think it would matter.

 

[atvman400]

Why would have a barrel threaded by a smith be any different than the factory? Both are going to use a lathe and remove material.
Threading the end of the barrel for a brake or can has lots of discussion on loss of accuracy. I don't see the argument on barrel blanks. Anschutz supposedly has choke in there barrels so if you remove any length off the barrel it will hurt accuracy.

 

[LeftyJason]

Why would have a barrel threaded by a smith be any different than the factory? Both are going to use a lathe and remove material.
Threading the end of the barrel for a brake or can has lots of discussion on loss of accuracy. I don't see the argument on barrel blanks. Anschutz supposedly has choke in there barrels so if you remove any length off the barrel it will hurt accuracy.

They don't necessarily need to use a lathe. @LongRifles Inc. uses a 5 axis mill and thread mills them.

It could possibly affect accuracy if you do too small of a thread on too big of a bore (too thin of walls).

@rockchalk06 I would just send it to LRI. $100 for thread and crown with very fast turn around times. Much cheaper than local guys to me and they check threads with the proper gaging. Did a great job on my 22lr.

 

[atvman400]

They don't necessarily need to use a lathe. @LongRifles Inc. uses a 5 axis mill and thread mills them.

Barrels? I don't think Chad has that big of a 5 axis mill to rotate a 30" stick and still machine. He spent a ton of time and money working on collets for the lathe instead of a 4 jaw chuck. I am willing to bet he hasn't given that up.

You are correct on using too small of a thread on a large bore. The issue isn't the thin walls unless you are going crazy and the thread is cutting into the bore. The issue is to high of hoop stresses for the material and getting elastic deformation that will effect accurracy. Hopefully you have competent smith that won't try and thread your 416 rigby barrel to 1/2-28.

If I was having a barrel threaded I wouldn't go anything less than 5/8-24, even for centerfire 22.

 

[Yondering]

Chances are that 24" factory barrel will be pretty thin at the muzzle, unless it's some sort of heavy barrel variant but you didn't mention that.
There are a number of guys who will thread 30 cal barrels to 1/2-28 for brakes, but personally I wouldn't do it for a can; I'd want to cut the barrel back. Once you do that, it can certainly change the loads lit likes, although it won't usually make it less accurate.

 

[Yondering]

If I was having a barrel threaded I wouldn't go anything less than 5/8-24, even for centerfire 22.

That's a bit extreme, and depends a lot on the application.

 

[Praeger]

Or, just go with a clamp on muzzle brake.

https://www.wittmachine.net/custom-clamp-on-muzzle-brake.html

 

[Gee Kay]

the only difference i noticed after i had my barrel threaded for a brake was it got louder cause of the brake but no accuracy issues at all.

 

[fdkay]

Is this a medium contour or thicker, such as a varmint contour?
If so, shouldn't be an issue.
Question is, how much money do you want to dump into a savage?

 

[rockchalk06]

Is this a medium contour or thicker, such as a varmint contour?
If so, shouldn't be an issue.
Question is, how much money do you want to dump into a savage?

Heavy barrel.

That was my whole thought process, until I shot that ammo. Right now it's holding a better 5 shot group than my HMR Pro

 

[LRI]

Barrels? I don't think Chad has that big of a 5 axis mill to rotate a 30" stick and still machine. He spent a ton of time and money working on collets for the lathe instead of a 4 jaw chuck. I am willing to bet he hasn't given that up.

You are correct on using too small of a thread on a large bore. The issue isn't the thin walls unless you are going crazy and the thread is cutting into the bore. The issue is to high of hoop stresses for the material and getting elastic deformation that will effect accurracy. Hopefully you have competent smith that won't try and thread your 416 rigby barrel to 1/2-28.

If I was having a barrel threaded I wouldn't go anything less than 5/8-24, even for centerfire 22.

Yes, my 5X is big enough to do a 30" stick. I could do longer than that even if I made new work holding for the riser block. Put it this way. 5-6 average sized adults could stand inside my machine.

For the record, last time I used a 4 jaw chuck on a lathe for a barrel job was 2003.

 

[LRI]

Here is what I've learned after doing this over and over and over for almost 3 decades.

Short answer: Yes, you can ruin a barrel or greatly accelerate its expiration date by threading the muzzle.

Here is why: (last few paragraphs of the LRI muzzle threading listing on our website)

GUNSMITHING SERVICES: Muzzle Threading AND Crowning service

The incredible surge in the popularity of suppressors makes a threaded muzzle virtually standard equipment on today's precision rifle. LRI is well equipped for this extremely popular upgrade. With our resources and experience, your device will attach trouble-free every time. Muzzle threads for...

www.longriflesinc.com

Last, the caliber and cartridge for a particular setup must be considered. As a rule, LRI requires a minimum of .100" of wall thickness between the groove diameter of the barrel and the root diameter of the thread being machined to the muzzle. This value is a judgment based policy as well. A 300-378 Weatherby Magnum is a powerful cartridge with muzzle pressures significantly higher than a 308 Winchester at a given barrel length. Wall thickness should be increased accordingly.

Our experience has shown that a thin wall muzzle has the potential to "bell mouth" over time. When a crown bell mouths, the accuracy of the rifle suffers. You as the user may be compelled to think the barrel "let go" due to throat erosion when it's actually because the muzzle was threaded with too thin of a wall thickness.



When I worked for Dakota Arms/Nesika this was a thing on some of the "boomer" calibers we'd chamber for on the 76 actions. Nitros, Rigby stuff, big WBY's, Lapua, etc. . . When using "spaghetti contour" barrels it was not uncommon for the gun to come back after a few miles for an accuracy issue when it had been fitted with a brake or whatever. It can be one of the most frustrating things on a rifle to try and diagnose. Thankfully we got in front of it shortly after I arrived there in the fall of 2003.

Hope this helps.