223 primer blow-by?
Greetings all, 1/22/13
I just got my LMT CQB .223 carbine in about a month ago after a six month wait. Fit and finish and function seem great. Twist is 1:7.
The only problem is that I'm getting powder blowing past parts of the primer causing bolt face erosion with about 10 % of my loads.
The reloading particulars- cases- new RP or once fired PMC, LC and FC. All are full length resized on my Rockchucker single stage press (even the new RP cases). Primers are Wolf Small Rifle primers, lot # 5-09.
Powder- IMR 4064 at 22-24 grains trickled or through a Dillon 650 (weighed charges are all close to the desired setting).
Bullets- Sierra 65 grain Spitzer Boat Tail.
Coal- 2.264" which just fits into my PMags and Brownells mags but is still about 0.020" off the lands.
Velocities- 22grains- 2320 ft/sec
23 grains- 2427 ft/sec
24 grains- 2528 ft/sec
I'm getting dark powder blowing past a part of the primer regardless of which powder charge I use. The powder charges seem to be below the max charges of my reloading manuals (Speer, Lyman) and there are no overpressure signs on the primers and the cases are not sticking in the chamber. The primers are seated below the case head and are still there after firing.
So any ideas on the cause of my primer blow-by? I normally reload a lot of pistol and rifle ammo (30/30. 270 Win, 30-06) and this is a new problem for me. I'm thinking a bad batch of primers but can use any ideas? Thanks.
best wishes- oldandslow