by Bmt85 » Tue Feb 26, 2019 3:20 pm
Things can happen, and some bolt's break. I had a 450B bolt crack in less than 100 rounds, and I was just starting to lean on it . It was supposedly 9310, which when treated properly, is stronger than Carpenter. I have 2 Carpenter 450B bolts, that I have pushed harder, and for a lot more rounds, they're still holding up. If your upper is a bit out of square, you can take a bolt out quicker, or take it out of spec where it won't work anymore. As to the Oly bolts, I wouldn't trust there 22-250 bolt to last a long time at 65K. 1-2000rds, maybe 3-4000rds. Wouldn't surprise me if they figure you'll burn the barrel out of that 22-250 before the bolt breaks, so your fine at 65K, when really, you probably aren't. Hell, look into some of the WSSM uppers. Some guys had their upper's grenade, I know a couple were stuffed into standard AR uppers, but I want to say a couple utilized a special upper with bigger bolts and bigger barrel extensions. So, yes, some companies rate things to levels that shouldn't be pursued.
In my opinion, an oversized bolt in a standard AR upper is pushing the limits at 60K. So far they seem to be holding up just fine. If you try going to a 450B case, I wouldn't worry about bolt thrust and bolt life so much, but as you mentioned earlier, the barrel tenon.