Type II bolt on a Type 1 chamber

[worthen86ford]

[Klem]

There will be 0.011" of extra case stretch. You risk case separation; every time or at least sometimes. Primer blow out, poor accuracy from sloppy fitting ammunition. Probably hard recoil and stress on the lugs. Likely the case will be held by the extractor so will still fire but yes, soft primer strikes. If you are handloading then it's only one firing and the case has fire-formed. If you shoot factory loads then expect this every shot.

No doubt someone else has actually had experience with this and can chime in.

[LR1955]

So what would be the issues with using a .136” bolt face depth on a chamber headspaced for .125” bolt face depth? Light primer strikes, accuracy issues, extraction and chambering issues?

W86F:

I did an experiment with this many years ago in an attempt to get a bit more powder capacity in the Grendel. The notion was that it would blow out the case neck a bit more.

No problems shooting the ammo. No light primer strikes or other problems. The experiment failed, though. The resulting case didn't completely form and left a very short neck. Can't recall how much more powder it could take but it wasn't very much.

I would not advise doing it for general purposes. Use the correct bolt for the chamber or expect to shear lugs very quickly.

LR55

[aephilli822]

i'm betting the opposite (type II chamber and type I bolt) wouldn't even chamber a round?

[HuntTXhogs]

i experienced case head separations when using a type II (Grendel bolt) in a Type I barrel. Out of 10 rounds fired I had 7 blown primers and 3 case head partial separations. Not exactly good stats not to mention the detriment to the gun and shooter...

Why did I perform this 10 round string of fire?

Because the Dude I bought it from (classifieds deal on a forum) was texting me that the gun was sound and good to go and it must be the ammo I’m using - - - sent him photos of factory and handloads both coming apart , pressed him on a phone call for the truth ...

Come to find out he had broken a bolt and reordered a new bolt and sold it to me with the new bolt having not been tested.

I bought a 7.62x39 bolt (Type I) at a gun show that weekend and performed the following test and wahlaah, presto, bang - it worked like it should

https://m.youtube.com/watch?v=DZncepUMgBg

You’ll note a Type II Bolt will chamber in a Type I barrel but a Type I Bolt shouldn’t chamber in a Type II barrel...

The difficult in testing this at home is you need to uninstall the extractor and ejector in the bolt to hand spin them like the guy in the video.

Have fun, stay safe, and don’t mix Types of bolts

[worthen86ford]

That’s the kind of input i was looking for guys thanks.

To be honest the reason i asked is because against my better judgement I ordered a BHW 14.5” .264 LBC MLGS from true sporting arms. I have the feeling of regret now and wish I didn’t do it but the barrel has shipped so cancelling the order and/or returning it will be more of a hassle than the $140 it cost me. The regret is mostly on the fact that these barrels are head spaced with a .125” bolt face depth and thus bolt interchangeability between my grendels will not be viable. Not a huge deal, but I’ve got to figure out what bolt i’m gonna go with.

[HuntTXhogs]

I put a Maxim Firearms Bolt in mine - they’re supposedly made to sustain high pressure

[NugginFutz]

That’s the kind of input i was looking for guys thanks.

To be honest the reason i asked is because against my better judgement I ordered a BHW 14.5” .264 LBC MLGS from true sporting arms. I have the feeling of regret now and wish I didn’t do it but the barrel has shipped so cancelling the order and/or returning it will be more of a hassle than the $140 it cost me. The regret is mostly on the fact that these barrels are head spaced with a .125” bolt face depth and thus bolt interchangeability between my grendels will not be viable. Not a huge deal, but I’ve got to figure out what bolt i’m gonna go with.

In your case, it is possible to use a finish reamer to deepen the headspace. (Assuming you crave it enough.)

On the other hand, if you want to continue with the barrel as-is, you can get the bolt from a number of places, including here:

https://www.tacticalammunition.com/264-LBC-Bolt-Head-Complete-Type-1-TA88-0412-TA88-0412.htm

ETA: FWIW, I have two BHW's, both headspace for .135", and both are fine barrels. Having a .125" headspace isn't the end of the world. Several members on this board have them and report few issues. Of course, YMMV.

[worthen86ford]

Headspaced to .125 is a deeper chamber than .136” so i’m stuck with the “type 1” bolt.

[NugginFutz]

Headspaced to .125 is a deeper chamber than .136” so i’m stuck with the “type 1” bolt.

Wups - thanks for correcting me. Somehow had that backwards in my head.