Primer Blow Out with NO Over Pressure Signs?

[BuffCyclist]

Okay, so I went to the range today in hopes of finding the perfect load for my Rem 700 5R.

Caliber - 308 Winchester
Brass - Lake City LR 07 - Once Fired from brassbombers.com
Primer - Winchester Large Rifle
Powder - IMR-4064 - 38.0gr to 42.8gr in 0.4gr increments (13 loads and 5rds per load)
Bullet - Sierra MatchKing 168gr
Brass length - 2.005"
Case OAL - 2.800" (+/- 0.001 - I was shocked my Lee dies held this precision)
Barrel Length - 24"
Weather - 72*F, 5-7% humidity, 5mph wind gusts (ie dead calm)

Started shooting at 1rd of 38.0, 1rd of 38.4gr, 1rd of 38.8gr, etc shooting about 1 shot per minute. I was putting each round into the chamber by hand, not using the internal magazine (not that it matters). Shooting prone, off bipod, factory rifle/trigger with SWFA SS 10x MilQuad scope in TPS TSR 30mm rings (again, not that it matters).

First 12 rounds (38.0 to 42.4gr) went great. All were shooting about 1" left of the target, then I got to 42.8gr, which is lower than IMR max load by 2.3gr (IMR4064, 308Win, 24" barrel, 41.5gr at 2518 FPS to 45.9grC at 2766 FPS) and BOOM! Much more noise, tons of smoke and immediately I looked at my hands thinking the worst had happened and perhaps I had just had a kaboom. No blood, whew! Check out the rifle, looks okay, cycle the bolt.... cycle the bolt... shit. The bolt is stuck. I couldn't lift it up even a quarter inch.

Made sure the bullet went downrange (and saw the bullet impact), got up and was able to force the bolt up then with a different hold and a lot more force was able to pull the bolt back scraping a huge flap of skin off my pinky knuckle, hurts like hell, bled a lot. Pulled the bolt out of the gun and the brass was stuck in the face of the bolt. Ended up taking it to the range master to ask him if he had ever experienced that, he said no, and we proceeded to take pliers and pull the brass off the bolt face. That's when we saw the primer just fall out onto the floor. The face of the brass letters are partly flattened, though I think that's more from using the pliers at an angle (gripping case mouth and torquing it out). Here's a picture (42.0gr, 42.4gr, 42.8gr).



The velocities for those 3 rounds were:
42.0gr = 2619 FPS
42.4gr = 2635 FPS
42.8gr = 2619 FPS (not sure if I believe this though)

As you can see, the primer is blown out. In fact, it has at least 0.04-0.06" play around the primer. The 42.0/42.4gr show only slight overpressure signs (round indent on 07 and LR), but those primers look perfectly fine, no cratering, no flattened edges, etc. After debating for a long time, looking at the rifle and it appearing fine in all functional tests I did, I decided this was a brass issue and that I'd keep shooting, perhaps avoiding the 42.8gr load.

Shot the 38.0gr load for the 2nd time and BOOM, same thing, only this time it doesn't lock up my bolt. Loads are 38.0gr on left, increasing to the right in 0.4gr increments. This 38.0gr load primer would fall out, but with quite a bit of smacking it on my hand, it was obviously loose but not as loose as the 42.8gr blow out.



So here I sit with 51 rounds of ladder loads ready to shoot in brass that has questionably loose primer pockets (they all seemed fine as I was priming them). What is the best course of action? Pull them all and try a different LC LR brass year and scrap the 2007s? Pull them and load up brand new, high quality brass (like Win or Lapua)? Toss my hat into the ring and swear off reloading for the rest of my life? Give up guns entir... haha, just kidding!

Here are the velocities I measured of 14rds I shot with a Competition Electronics Pro Chrono chronograph with brand new batteries.

38.0gr = 2351 FPS
38.4gr = 2376 FPS
38.8gr = 2389 FPS
39.2gr = 2415 FPS
39.6gr = 2464 FPS
40.0gr = 2487 FPS
40.4gr = 2482 FPS
40.8gr = 2515 FPS
41.2gr = 2569 FPS
41.6gr = 2583 FPS
42.0gr = 2619 FPS
42.4gr = 2635 FPS
42.8gr = 2619 FPS

38.0gr = 2287 FPS

According to the 308 Win Single Load Manual, with IMR-4064 in a 24" barrel, I should expect these velocities with the 168gr SMK.

37.8gr = 2400 FPS - Measured 2351 FPS
39.7gr = 2500 FPS - Measured 2464 FPS
41.5gr = 2600 FPS - Measured 2583 FPS
42.2gr = 2700 FPS - Measured ~2620 FPS

eta: Another question I have to ask, is do I need to be concerned that this did any permanent damage to my rifle, as in, do I need to ship it off to a gunsmith for inspection? (It'd go to BPTactical, I have no direct experience with him, but everything I've read on here, he's the one person I'd actually trust... Not to mention there are no reputable gunsmiths in the area).