02-06-2012, 06:35 PM
elkbow Wrote:thanks for the info, I had read quite a bit about failed bolts for 7.62x39, even in that cartridge....but the 7.62x39 bolt is a little less recessed than the standard Grendel bolt, correct?, which should with a deeper chamber and strong bolt allow greater pressures? Also, I think the superbolt that ARP makes will handle about anything thrown at it. I'm going to try their new barrel/bolt combo for my next Grendel build and see how their chamber and 5R rifling does for accuracy, looking for a hunting rig, don't mind carrying around my 24", but like the 18" size and I use mainly 16" in my 6.8's, two being 16" (well actually 3 as I have another coming in today, the Bison 16" BSP that i'm going to try subsonic) and one being 20"
Theoretically, more steel should be stronger, but if you use the inferior steel of Carpenter 158, all bets are off, and most 7.62 bolts were/(are?) built with that. In addition, the shallower bolt face creates issues with the extractor claw, which needs to be deeper to grab the thicker rim of the Grendel case. If you take metal off the top of the claw, it weakens it too much causing failure. Thus you have to deepen the face, and make the cut towards the tail, to leave enough meat on it to be stronger.
ARP's bolt may be the answer, but he has made a completely different chamber and barrel extension.....with a .297 neck! If he would just use a standard Grendel chamber I would probably eventually buy one, if for no other reason than to see just how strong the Lapua brass is! The other issue will be what happens for parts, since he is the only one building that bolt and barrel extension, but since it is essentially a custom build, that's the price you pay to play.
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt