08-12-2022, 02:52 AM
I've recently come close to putting closure on close to 3,000 rounds of converted Starline 7.62x39 in a 243 LBC (aka 6 Grendel) with much success. That barrel is pretty much shot out (5k ish) and I'm going to put closure on a long thread about it when I do. I've got about 150 rounds of MOA ish ammo ammo left to shoot and then I'm going to take what brass is left and load it with 400 or so really gnarly pulls with some Magnum LP primers I have absolutely no other use for and do close range speed practice.
My biggest takeaway is that using a Large Primer results in faster ignition and hence and earlier pressure peak. The end result is that using traditional powders for the caliber results in lower attainable velocity. That wasn't a big deal for me since I used x39 brass for mild loads.
I didn't find that the LP results in shorter primer pocket life. In fact, I got better pocket life out of Starline LP x39 brass than I did out of Starline small primer 6.5G brass that I converted to 6 ARC. My x39 loads were milder, though.
You mentioned crushed shoulders. My theory is that AKs etc. are so violent with extraction that the rim gets bent. If you use range brass, the case mouth can be slightly off center as it goes up into the die and the crushing begins.....
Use fireforming loads to practice standing speed and double taps. I use 1/3 and 1/4 USPSA target photocopies at 15-25 yards to simulate 50-100 yards (recognising that impacts will be 1.5-2" low. But it takes bullet flight out of the equation).
And if your not annealer, don't worry about annealing (but if you are, annealers are gonna anneal!).
Best of luck!
My biggest takeaway is that using a Large Primer results in faster ignition and hence and earlier pressure peak. The end result is that using traditional powders for the caliber results in lower attainable velocity. That wasn't a big deal for me since I used x39 brass for mild loads.
I didn't find that the LP results in shorter primer pocket life. In fact, I got better pocket life out of Starline LP x39 brass than I did out of Starline small primer 6.5G brass that I converted to 6 ARC. My x39 loads were milder, though.
You mentioned crushed shoulders. My theory is that AKs etc. are so violent with extraction that the rim gets bent. If you use range brass, the case mouth can be slightly off center as it goes up into the die and the crushing begins.....
Use fireforming loads to practice standing speed and double taps. I use 1/3 and 1/4 USPSA target photocopies at 15-25 yards to simulate 50-100 yards (recognising that impacts will be 1.5-2" low. But it takes bullet flight out of the equation).
And if your not annealer, don't worry about annealing (but if you are, annealers are gonna anneal!).
Best of luck!
Let's go Brandon!