Blew my Lilja AR24 barrel extensions to pieces today. Bolt blew apart a few weeks ago so maybe it did some damage to the barrel extension? Seems very odd, thoughts?
6.5 Grendel Group Buy Bolt 1/ Barrel Extension 0
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That made a mess. What happened when it failed. Looks like the extension sheared off all the way around just in front of the lugs? Did it come off in a ring? Upper damage? How’s the bolt look now? Ha. You’ve gotten me curious!Nothing kills the incentive of men faster than a healthy sense of entitlement. Nothing kills entitlement faster than a healthy sense of achievement.
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Casualty list: ASC 20rd mag (feed lip ripped off), BCM Gunfighter charging handle (probably saved my face) latch handle sheared off, VLTOR MUR Upper - various gashes/chunks in carrier raceway, Group Buy Grendel bolt extractor (rest of bolt looks great - BFT - awesome piece), Front take down pin bent. Everything else is pretty much fine. Pics of bolt below.
My going theory is the barrel extension or factory bolt (Headspace) was out of square to the barrel. Receiver was lapped, barrel bedded, so somewhat confident of trueness of those faces. The factory bolt from Lilja broke a few weeks ago (Hence grendel group buy bolt replacement). Those bolt lugs showed some heavier wear on one side. I'm guessing the factory bolt went first and probably had caused some damage to barrel extension (or maybe the bolt was working one side of extension and causing fractures??). Had probably 800 +/- Rds on it. When I replaced with new bolt (has not shown any unusual wear as of d-day) the extension finally gave up. Of course a hot load could have helped further the cause. However, since my bolt failure I have been trimming, inspection, hand throwing & chronoing (magnetospeed) every batch of ammo. All lapua brass which has shown no pressure signs. I shoot PRS and handload all my dasher/creed rounds so feel somewhat confident my loads didn't get squirrely. D-Day happened on probably the 25th or so round of the day during a PRS practice running strings off a cattle gate. Suppressed Grendel out to 840yds for PRS practice is a blast BTW! So definitely bummed the rig is down. I have contacted Lilja to send the barrel back. My local smith didn't want to mess with it...... What you think? Sound probable? What else could I be missing? The hot load theory always comes up but I would assume the bolt would give before the extension??
Last edited by brut28481; 01-06-2018, 03:19 AM.
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Woah, hope you're OK. Nothing in your eyes?
Your load is hot, but not by much. I load no more than 28.5/8208 with the 107SMK. It's not going to be the suppressor because by the time the bullet gets to it the peak pressure has dropped dramatically. Your earlier damaged bolt is too much of a coincidence to ignore. It sounds like either that first bolt was faulty and caused stress in the extension which took a few more rounds to fail, or as you say, the extension was faulty and this damaged the first bolt, and eventually failed completely.
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I hope first of all that you didn’t sustain any injuries. I knew an Air Force CATM Instructor who had to have reconstructive surgery after an M-60 cover blew off in her face. They did a good job, as I wouldn’t have known if she didn’t use it as an instruction lesson prior to our range time. Just as we should never take firearm safety for granted, we should never forget that a malfunction could turn hazardous to one’s health. So hopefully you’re safe and sound, even though your weapon is not.
And here’s to getting it up and running soon. I don’t have enough expertise to weigh in hear, other than to agree that the thoughts postulated so far seem very plausible.-Zac
Husband, Father, Veteran. Grateful for my redemption.
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Oh my that extension looks like it's got a ring of Playdough on it. Are you really sure you trued the face of receiver or exacerbated it with the hand held truing device? Will say I never had complete faith these hand held truing devices and have sent a couple of receivers to a machinist who trues them on a lathe turned on a mandrel to within .001 inch to help insure that your sights will zero near the midpoint of their adjustment range for about $10.
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