6mm ARC

[LRRPF52]

I just received my Shaw 6mm ARC barrel yesterday and this thing has a short throat. Both Hornady 108s and 105s are sticking horribly and the bolt won't close. This is with a .136 Grendel bolt. I tested with the ejector and extractor removed. This bolt, although never fired, has been used to test headspace on Go/No Go gauges in a Grendel barrel, so I know it's not an issue with the bolt.

Shaw asked me what bolt I was using and I told them .136. Their reply was "The bolt face is not deep enough, the ARC uses a Grendel 2 headspace off of a .140 depth bolt face."

I asked them where they got that incorrect information (I assume the person is rounding), and I'm waiting for their reply. But that doesn't give me much confidence in them. Never mind that even if the bolt depth was .140, the lugs still wouldn't engage in the barrel extension properly (see pic #2).

Also, the packaging that this barrel came in was destroyed when I received it. I really thought the barrel was going to be damaged but it appeared to be fine once I got it out. Boy am I disappointed; I had all of my other parts ready to assemble so I could shoot this weekend.

[ATTACH=CONFIG]16817[/ATTACH][ATTACH=CONFIG]16818[/ATTACH]

Even if we give them the benefit of the doubt with this “Grendel 2” misnomer, there is no .140” bolt face depth. It’s .136” (-.003” tolerable, not +.004”).

Every new cartridge seems to go through this reamer spec madness once the high volume production makers get a hold of it.

Once everyone gets in a tizzy, the reamer maker will announce their “fix” to the reamer design, call it theirs, and push their new name for it, adding more confusion.

It’s one of the reasons why I normally just wait for at least 3 years to let all the dust settle, or just have Manson make the reamer.

Getting ammunition manufacturers and reamer makers on the same sheet even with SAAMI specs is pretty difficult for whatever reasons.