Even the pretty Grendel bolts can shear

[DVDVC]

Very interesting. I just put together an upper with the same JP barrel and head spaced bolt combo. Still waiting on an Aero Precision complete BCG for the 6.5 Grendel. So it hasn't been shot yet and no available factory rounds at the moment. Nor do I have any dies for it yet. Wondering if I should use the AP bolt and forego the JP bolt?

[StoneHendge]

Very interesting. I just put together an upper with the same JP barrel and head spaced bolt combo. Still waiting on an Aero Precision complete BCG for the 6.5 Grendel. So it hasn't been shot yet and no available factory rounds at the moment. Nor do I have any dies for it yet. Wondering if I should use the AP bolt and forego the JP bolt?

I'm pretty confident that the problem wasn't the bolt. So confident that I'd offer you $130 for the shiny new JP bolt if you want to use the AP. It would go nicely with the Lilja 6 ARC barrel I have coming.

[DVDVC]

Thanks SH, but I'll keep both bolts, nice to have extras on hand.

[StoneHendge]

Thanks SH, but I'll keep both bolts, nice to have extras on hand.

It was worth a try. The only way to get ones hands on a JP bolt these days is to buy a barrel to go with it and wait 4-6 months!

[StoneHendge]

The ugly old spare bolts with ~6-7k rounds on them can shear too.

IMG_20210321_080341_copy_1095x715.jpg

Separation papers will likely be filed.

[D.Davis]

SH do you lap your bolts? Dave.

[VASCAR2]

[Klem]

SH,

+1 (VASCAR)

Your bolts are getting hammered or are brittle/weak.

[StoneHendge]

Thanks guys. In this case I think it was probably just an old brittle bolt that was sitting around as a spare after serving another barrels useful life. Load was mild and is undergassed (bolt won't lock back with it on empty mag due to frozen gas block adjustment screw), scale works fine - I've loaded and shot hundreds of rounds for other rifles (including 90 rounds in my 6.5CM at a PRS match where I came in second in the Gas Gun Division behind Rob Leatham (okay, we were the only 2 gas guns, but I still get to say I came in second only to Rob Leatham! (and my 71 was respectable))), no extreme temp (plus I was using H322), and I was 0.05" off the lands.

Maybe it is something with with the x39 brass and LRP - my 243 LBC doesn't have a problem with it though. Maybe the case head with an LRP only likes a 0.125 bolt face depth. Or maybe my barrel extension got damaged (somehow previously, or durning the first shear). It's moot though - my commitment to 6.5G has been tenuous since I moved to a warm climate and have been unable to find a temp insensitive powder that works with 123s. That, combined with a complete lack of suitable projectile availability for the cartridge had me planning on shooting my stash of 85 grain Sierras in x39 brass with LRPs and then reassessing when they were gone. How silly is it that I've been shooting a bullet with a BC below that of a .224 55 gr FMJ out of a rifle with an Elite Tactical HDMR2 with an H59 reticle?

The only decision I'm let with facing is if I want to go with a .223 barrel or 6 ARC. As Roland Deschains would say, "the world has moved on". In target bullets, the only projectile technological development there's been in bullets suitable for 6.5G since I got into it has been Sierra putting a tip on the 107s (unless one considers Hornady replacing the melting Amax tip a technological development) while strides have been made with high BC .224 and 6mm target bullets.

[LR1955]

Thanks guys. In this case I think it was probably just an old brittle bolt that was sitting around as a spare after serving another barrels useful life. Load was mild and is undergassed (bolt won't lock back with it on empty mag due to frozen gas block adjustment screw), scale works fine - I've loaded and shot hundreds of rounds for other rifles (including 90 rounds in my 6.5CM at a PRS match where I came in second in the Gas Gun Division behind Rob Leatham (okay, we were the only 2 gas guns, but I still get to say I came in second only to Rob Leatham! (and my 71 was respectable))), no extreme temp (plus I was using H322), and I was 0.05" off the lands.

Maybe it is something with with the x39 brass and LRP - my 243 LBC doesn't have a problem with it though. Maybe the case head with an LRP only likes a 0.125 bolt face depth. Or maybe my barrel extension got damaged (somehow previously, or durning the first shear). It's moot though - my commitment to 6.5G has been tenuous since I moved to a warm climate and have been unable to find a temp insensitive powder that works with 123s. That, combined with a complete lack of suitable projectile availability for the cartridge had me planning on shooting my stash of 85 grain Sierras in x39 brass with LRPs and then reassessing when they were gone. How silly is it that I've been shooting a bullet with a BC below that of a .224 55 gr FMJ out of a rifle with an Elite Tactical HDMR2 with an H59 reticle?

The only decision I'm let with facing is if I want to go with a .223 barrel or 6 ARC. As Roland Deschains would say, "the world has moved on". In target bullets, the only projectile technological development there's been in bullets suitable for 6.5G since I got into it has been Sierra putting a tip on the 107s (unless one considers Hornady replacing the melting Amax tip a technological development) while strides have been made with high BC .224 and 6mm target bullets.

SH:

Having sheared lugs on a number of bolts over the years using Lapua or Hornady brass as well as 7.62 X 39, your conclusions are as good as any.

I think the 6 AR or 6 ARC is a great cartridge for High Power where a guy is in the pits who can look for the holes and spot them. For steel? Who ever is scoring better be really good because it is really hard to see splash with a 6mm or under and hearing the steel get hit is more difficult. Particularly when the steel is near ground level where even strong winds won't blow out mirage. Flag targets? Lesser a chance a scorer will see one move if you hit it on an edge.

Having shot the 6 AR competitively, I will say it is ideal for Over the Course. I will also say that I think you got to watch the loads because of pressure, particularly when in heat. If you can't find a temp stable powder for your Grendel, you will have big problems with a 6 ARC or 6 AR. My opinion only based on shooting the 6 AR.

I shoot a 6 BR for prone matches now. I have a bunch of 95 and 107 Sierras so that is what I use. Am sure these are considered obsolete these days but they hold their own. Tried the heavier 6mm bullets and found them lacking.

Good luck in your search!

LR55