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Old January 24, 2013, 01:50 PM   #16
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Join Date: October 18, 2006
Posts: 7,089
My only observation is; why are you using 4064 powder? It's too slow for .223, I think you're seeing signs of way TOO low pressures. Especially when you consider the very slow velocities. Might just be lack of pressure NOT creating a good seal around the outside of the primer cup.
IMR4064 should be ok with a 69gr SMK, I didn't have any problems using 4064 with 68gr Hornady's. Now I'm using Power Pro 2000-MR which has an even slower burn rate, but with 75 and 80 gr bullets.

But I think a faster powder would be smart with such a short barrel.

Machine guns are awesome until you have to carry one.
Jimro is offline  
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