Is my Type 2 chamber not Type 2?

[LRRPF52]

Thanks everyone - allowed me to consolidate my thinking enough to give them a call. Was lucky to have the guy who runs QC answer the phone. Had a nice long chat with the conclusion being that being .01 longer than the JP brass would not be out of the ordinary and being around .01 longer than the Type 1 brass would be expected. Long and short of is: remove the firing pin from a Type1 bolt and see if it locks down on Match Grade ammo. So I got home and did the test with StoneHendge Enterprises 123 gr Scenar ammo that gets fed to the JP and voila!

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I might not be too happy with a chamber deep enough to make Stormy Daniels proud if I was using Hornady brass for anything else in 6.5mm, but I'm not so I guess I can live with it.

Other random takeaways:

He gushed praise about JP and his tolerances when I brought up the JP measurements - pretty compelling coming from a QC guy. This is the third company I've talked to that had that reaction. Conversely, he was uncomplimentary of some of the things he has seen in the market, such as bolt faces that could vary by .002 from side to side. Not necessarily a disaster in and of itself, but scary when tolerances begin to get stacked.

With having made close to 10k LBC barrels, they've seen very few problems with Type 1 bolts and don't see any real upside to AA coming out with the Type 2 given the confusion it created since the AR market already had an effective solution. (I'm not starting a debate here - just passing along the view from a respected barrel maker that decided to stop making barrels headspaced to Type 2)

I asked if they would do twist rates that aren't on their website and the short answer is maybe. But the one takeaway was that their 3 groove rifling can have a hard time gripping when long bullets start getting pushed fast at high twist rates. Made me start to wonder if this is one of the problems with the Valkyrie - Sierra says 1:7 isn't fast enough for the 95s, but the barrel makers haven't jumped to embrace 1:6.5 (aside from ARPs run which was a failure). Also makes me wonder if that's why my McGowen 1:7 6mm Grrrr barrel didn't really show promising accuracy (other than the fact that it was a hack job)

Bill Alexander introduced the .136" face depth on the .50 Beowulf after doing a lot of research, which included the Colt 7.62x39 program.

Extractor lip geometry and material thickness is what gets you with the thicker and wider rim.

There is no Type I or Type II relevant to the whole industry. There are bolts that were engineered around the cartridge, and bolts that were engineered around convenience for the after-market, not fully understanding all the details of what it takes to make the whole thing work.

Barrel makers specialize in making barrels.

Firearms manufacturers specialize in sourcing all the components after RDT&Eing their overall design, and holding component suppliers to their standard as part of the TQM process. The firearm manufacturer is the one responsible for whether or not the extractor holds up, not the barrel maker. Same for bolts, springs, carriers, gas keys, gas blocks, tubes, fire control parts, etc.

What I've come to learn is that there are some very gifted people in this industry within their own discipline, but once they step even a little bit outside of their expertise and into another component or process on the gun, they are underwater really quick.

Even within the barrel-making process, that is true. Some places can drill a nice hole and rifle it, lap it, but the moment you ask them to finish profile, thread, attach an extension to it, you get a monstrous abortion sometimes.

The same goes for bolts and extractors. I will rarely place much value in what a barrel maker has to say about components they don't make, other than usual observations about quality and characteristics from different shops they've seen. It doesn't mean I'm trashing their reputation or hating on them, just putting into context where expertise should be recognized.

If I'm a home-builder, I'm not going to ask the plumbers how to do my foundation. The plumbing and drainage will certainly be taken into consideration when pouring the foundation, but the plumber won't be doing the job.