09-15-2014, 11:39 PM
Yes, I also don't normally put a lot of faith into ballistics programs, but I have learned that if you have solid atmospheric data, and true muzzle velocity data, you can be dead-on at ranges that were previously "walked into".
At the altitudes where I shoot at, I found that the 123gr A-MAX factory load is still supersonic out to 1318yds for me in 80 deg F, at 4400ft elev. 14.4 mils was what my program told me I would need for 1200yds, and the first shot literally barely missed the left edge, which then became my aiming point in the reticle for the next four rounds. That opened my eyes up to what this thing could do.
As to .308 AR's, I doubt I'll ever own one again, and I've had several of them, 5 total, 3 chambered in .308, and 2 chambered in .260 Rem. In the process of building more Grendel's as we speak. The only AR10 I'm looking at now is the Freedom Group GII, but it will have to be re-barreled from the start in .260 Rem., with a bunch of custom work.
They're still working on the bolt and firing pin hole diameters for the GII, since it exhibits the same problems other .080" AR10's. The elongated pressure curves of long bearing surface pills with slow powders hits the AR10 gas port hard, and also burns through primers if things aren't set up right.
SG4247 sent me a firing pin upgrade for my .080" firing pin hole AR10 in .260 Rem., which has been working well since I installed it. I push 129gr and 130gr class bullets at 2800fps from a 22" barrel, but it's a reloader's cartridge only with that rifle. No way would I shoot factory .260 Rem. from it. I have to size all my brass before loading too, so you'll understand why my Grendel's go out to play more.
At the altitudes where I shoot at, I found that the 123gr A-MAX factory load is still supersonic out to 1318yds for me in 80 deg F, at 4400ft elev. 14.4 mils was what my program told me I would need for 1200yds, and the first shot literally barely missed the left edge, which then became my aiming point in the reticle for the next four rounds. That opened my eyes up to what this thing could do.
As to .308 AR's, I doubt I'll ever own one again, and I've had several of them, 5 total, 3 chambered in .308, and 2 chambered in .260 Rem. In the process of building more Grendel's as we speak. The only AR10 I'm looking at now is the Freedom Group GII, but it will have to be re-barreled from the start in .260 Rem., with a bunch of custom work.
They're still working on the bolt and firing pin hole diameters for the GII, since it exhibits the same problems other .080" AR10's. The elongated pressure curves of long bearing surface pills with slow powders hits the AR10 gas port hard, and also burns through primers if things aren't set up right.
SG4247 sent me a firing pin upgrade for my .080" firing pin hole AR10 in .260 Rem., which has been working well since I installed it. I push 129gr and 130gr class bullets at 2800fps from a 22" barrel, but it's a reloader's cartridge only with that rifle. No way would I shoot factory .260 Rem. from it. I have to size all my brass before loading too, so you'll understand why my Grendel's go out to play more.