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Originally Posted By: bakerboy Blew up my AR with 24 gr of H335 and a 69 gr Sierra. Their data said 23.8 max. Ok my fault. I thought I had worked up to this load but maybe the much larger bearing surface of this bullet fooled me. Still a basically max book load blows up a gun???? Please note: I only have H335 so it wasn't a powder mixup. I pulled all the remaining bullets and reweighed the powder. 23.8 so no weighing problem. I always check my balance beam with a bullet, so that is not the problem. So I reload the Sierras 69 gr ( .2235 per my mic.) So it's not the wrong bullet. Using 22 gr of H335.(scale again verified with bullet). Now get this, 22 gr is below the minimum of 23 gr which is listed as 2700 fps. My 22 gr loads popped the primers. I didn't know on the first but the second didn't eject and when I pulled it the primer fell out so I immediately stopped. I checked the chrony. 3100 fps. This is not possible. The first bullet was a bullseye and the second never even hit the target. I found a flattened jacket stuck in the plywood below the target. My Krieger barrel looks ok to me. This is some crazy stuff happening. I only know to pull about 50 rounds and start over with different powder unless my barrel is causing this which I don't understand at all. HELP!!!!


Check your case length first.  If cases are too long for your chamber, they cannot release the bullet and pressures really skyrocket!


If bullet is jammed into rifling, pressures can also skyrocket.  As has been asked, what chamber do you have in your rifle?  Standard .223 chambers do not have the leade that 5.56 chambers do and can run pressures up, especially on hotter loads or long loads.  Allowing bullet to jump before contacting rifling will lower pressure. 



Not a lot of difference in case weight on 5.56 mm brass & .223 Rem.  Here is comparison of 3 cases ea.

LC 02 Nato 92.1 gr, 91.6 and 91.1

WCC 14 Nato 93.8, 93.8,94.1

LC11 92.5,92.8,92.9

Win. Commercial 96.093.0,93.8


Both GI 30-06 & 7.62 NATO brass was thicker than commercial, as a rule, however.


One thing you could do is to chamber a loaded round by letting bolt fly, remove round and see if you're getting rifling marks on the bullet. Since you were still blowing primers w/lower load,

OOps, I'm slow typist, I see you have already checked this issue.


I'd take a long hard look at case length, though.


Regards,

hm


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