Getting started with the 300blk ...
- Thread starter wquiles
- Start date
wquiles
Well-Known Member
OK, BO barrel hasn't been cleaned for a long time. Yesterday, ~45 shots BLL 2x coated on a slick sided GC 145gr AC ~50/50 alloy (2% Sb with just a touch of Cu added). 1:10 18" AR carbine bipod and a sandbag on the stock. No mirror on borescope but CLEAN! Thank you BEN. This stuff is great! Some of the fired ones were 15gr 296, lot were 16 gr so 1800 fps min. Sized 3085, just above bore. HT, 1x BLL and GC sized, 2nd BLL, same alloy. Results after range re-opens, push it harder - 19gr 296..
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.Range day. 142gr GC 2x BLL 18.5gr A2400 carbine (~2200 fps) and 170 PB PC 8.5gr A2400 pistol (~1300 fps). 8.5 cycles and lock back for pistol 3x scope. Bipod and rear sand bag for both. No leading in either. GC are not factory. Alloy is 50/50 H.T. for one hr.
Edit:
Target marked 185 GC for pistol, actually 170 PB. Was basically test of BLL, I'll add some As next time for faster hardening.
Edit:
Target marked 185 GC for pistol, actually 170 PB. Was basically test of BLL, I'll add some As next time for faster hardening.
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Case measures OK up to the 'expanded' part, no primer. One still stuck in chamber!
Ian
Notorious member
It takes like 90K psi to do that to a .223 case.
Sum Ting Wong, bigtime! I see a split neck, maybe loss of tension resulted in hangfire=SEE against a bore obstruction (bullet pushed into throat).
Have I mentioned here on this board how much I dislike WW296? In any cartridge?
Sum Ting Wong, bigtime! I see a split neck, maybe loss of tension resulted in hangfire=SEE against a bore obstruction (bullet pushed into throat).
Have I mentioned here on this board how much I dislike WW296? In any cartridge?
No splits, proper case length, proper dia. New w296, h110 used up. I'll pull some for check load, Bore scope shows a little lead near muzzle. Not a slam fire. I figure pressure started ejection, then more pressure. Could be blown primer caused unlock and high pressure.
Ian
Notorious member
I don't think a blown primer will cause an AR-15 bolt to unlock, but I could be wrong. I've blown maybe a dozen primers from 5.56 factory ball ammo in my AR with a an "AR Stoner" 5.56 barrel that is not actually so chambered (read TIGHT .223 chamber neck and throat) and had no other pressure signs or rim damage from forceful ejection. I think you're due for a headspace check for locking lug setback and feeling for bore bulges with a tight patch after you get the lead out of the barrel.
CWLONGSHOT
Well-Known Member
I agree. That AR bolt either fired out of battery or opened prematurely. This flat shouldnt happen in a AR. Heres another. Was your powder hopper empty when ya switched powders?
The AR bolt is locked breech. Obviously the pressures where quite high when that bolt started to open. Open THAT far would not fire so it absolutely was more Closed. POSSIBLE not completely locked so check those lugs and clean them out.
Thisnis a common think in a blow back action pishing velocities with some powders. But not usual in a AR for sure.
Good luck
CW
Got the bolt out (nice cycle tire tool use) blown primer not pierced. Everything looks fine, so far, no leading in the barrel by calibrated eyeball. Of course chamber is DIRTY! My take is THIS pound of W296 is hotter! I've run same load with H110, same everything and as some did OK yesterday (they shot fine), different batch at upper end is not good. I would have stopped if I'd seen the problem but cases ejected fine but the last one. I'd shot this load in the pistol and ripped a couple rims, figured it was due to pistol gas. This one is carbine. Basically load must be on the ragged edge of over pressure with this lot of powder. Pull what I have left and drop a full 1 1/2 grain. I'll clean and check the barrel later but I don't see any damage.
Not a slam fire, I pulled the trigger. I never keep any powder in the RCBS hopper _ reload on my WORKBENCH. Everything but the press is put away on the shelf or cabinet.
edit: only a few speckles in the barrel.
bright and shiny, no tight or lose spots. Lots of crud in the extension so cleaned it out. No bolt head erosion or FP problems.
Didn't crony any of these but proof that 2x BLL works well at HV, purpose of test. Next the 308W.
Edit: weighed 5 pulled, 18.5 gr W 296. Pulled all loaded, just lost some GCs. Must be difference in lot?
Not a slam fire, I pulled the trigger. I never keep any powder in the RCBS hopper _ reload on my WORKBENCH. Everything but the press is put away on the shelf or cabinet.
edit: only a few speckles in the barrel.
bright and shiny, no tight or lose spots. Lots of crud in the extension so cleaned it out. No bolt head erosion or FP problems.Didn't crony any of these but proof that 2x BLL works well at HV, purpose of test. Next the 308W.
Edit: weighed 5 pulled, 18.5 gr W 296. Pulled all loaded, just lost some GCs. Must be difference in lot?
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Ian
Notorious member
That bulge isn't from firing out of battery or unlocking at high pressure. Some things would be different such as taper-bulged and ruptured case head instead of the step, and Popper would have a buffer weight stuck in his shoulder instead of a case with torn rim stuck in the rifle. There really is that much unsupported case head sticking out of an AR chamber, and it will run around 55-60K psi all day long with no bulges whatsoever. The bulge pictured was excessive chamber pressure without breech failure...a testament to the strength and margin of error in the design.
Hawk
Well-Known Member
My first thought was a double charge or something like that, but not with multiple cases.
Also, I understand you went from H110 to W296. I've never used H110. Is there that much difference between H110 and W296? Could that have been it?
I'm like you, only one jug of powder on the bench at a time. That way I know what's in the hopper!
Also, I understand you went from H110 to W296. I've never used H110. Is there that much difference between H110 and W296? Could that have been it?
I'm like you, only one jug of powder on the bench at a time. That way I know what's in the hopper!
H110 and W296 ar SUPPOSED to be the same powder, Hodgdon just relabeled it. Same with W231 and HP-38. IMHO, now that I pay attention, Ian is right, just too hot a load. Seen comments about 10% maybe between lots of powder, just didn't figure for it and work the load up. First loads from 296 can. My bad.