Gunsmithing 1.25” shank with 1.125 action threads…
- Thread starter HerCoStarNTheBeaverPictur
- Start date
not sketchy unless you're going over 338 which it doesn't look like is offered on this action bolt. if it was sketchy bat wouldn't;t recommend it to their customers. if you're still worried call them and ask I'm sure they know best
That was my thought as well but wanted to get more opinions because the guy who was concerned is much more experienced than me.
I also just heard back from the ‘smith I’m planning to use and they said it’s ok.
Thanks for your input. This is for a 7PRC btw
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His concern is that you have 1/2 the shoulder area contact that you'd have with a "standard" 1.062 major diameter on the typical 1.35 receiver.
Apparently he's decided an additional 1/16 of steel around the chamber is mo better than the keeping that material for the shoulder, I don't see any other relevant factors. Gotta say, I don't get it personally but I'm sure someone here can enlighten...
A lot of customs nowadays offer .750 bolts for boomer builds on standard diameter actions, others like Stiller use the 1.125 tenon on a 1.40 action which seems more logical to me. But what the fuck do I know, I'm not a metallurgist...
But as far as I can tell, the shoulder doesn’t hold anything in place or serve a purpose other than allowing you to get the proper torque on the threads. If you can achieve that torque, then I fail to see what the size of the shoulder matters.
And I’m definitely a noob here so not trying to argue. Just thinking about it from a noob perspective and am genuinely curious
My bat igniter long action 300 norma imp is 1.125 tenon thread, and I'm using a 1.250 barrel, no issues. A 1.20 shank will NOT work.
Partially correct.
The shoulder is what allows you to achieve (when done properly) perfect alignment and perpendicularity of the barrel to the receiver ring.
Thin metal deforms under excessive stress, right?
As an example, consider the typical large ring (K98) Mauser. Receiver is 1.410 in diameter, the secondary torque shoulder on the barrel (think of it as the same as the shoulder on your barrel) is only 1.100. There's barely any "shoulder"- which is why the barrel is designed to seat on the much more substantial inner torque shoulder in the receiver at the same time. If you didn't have the inner torque shoulder, you'd crush/deform the shoulder and the receiver ring as well.
I'm not saying that's the case with the BAT and a 1.250 barrel, just illustrating with an extreme example. Having the receiver ring and the barrel shoulder being perfectly aligned and perpendicular to the bore/chamber/bolt raceway is critical for best accuracy.
That's exactly the point - the shoulder is serving a rather important function, and must do so through the dynamics of the combustion process. You're down to 0.0625" of nominal radial contact on the shoulder, and have yet to subtract anything for tolerance or chamfer on the action threads (I don't know what this dimension is on a BAT action, but I'm eyeballing a Zermatt TL3 on my bench and it's maybe another 0.015" radially).
I don't think any of this will lead to a safety issue and probably won't be a functional problem, but on a build of this level I feel it's important to sweat the details.
Agreed. That’s why I wanted to get more input from the community here, as well as make sure the person doing the build would be comfortable putting their name on it with these parts.
I’m going for a relatively lightweight build here and Bartlein only goes up to 1.25” on the carbon fiber barrels.
All bat HR/Igniter/Vesper long actions have 1-1/8" tenons. Guys build hunting rifles on these all the time. With 1.250 shank barrels, never heard of an issue. The Borden Bigfoot action, Same 1.125 tenon thread, I know a builder who puts 1.250 shank proof carbons on them all the time. Guys this is not a problem. Call Bat! Talk to Daryle, he'll put your mind at ease.......
I don’t have anymore concerns after the smith said they’ve done it before on this action and don’t have any concerns with the parts.
I did want to understand people’s concerns a little better just for my education
