03-11-2020, 11:45 PM
Klem,
My velocity is in line with what quick load predicts for my setup:
Cartridge : 6 mm AR
Bullet : .243, 105, Berger VLD Hunt G7 #24528
Useable Case Capaci: 30.583 grain H2O = 1.986 cm³
Cartridge O.A.L. L6: 2.250 inch = 57.15 mm ****I am using 2.260 COAL****
Barrel Length : 22.0 inch = 558.8 mm
Powder : Hodgdon H4895
-10.0 86 24.39 2448 1398 42272 7542 97.1 1.298
-08.0 88 24.93 2498 1455 44889 7694 97.7 1.262
-06.0 90 25.47 2548 1513 47662 7837 98.3 1.228
-04.0 92 26.02 2597 1572 50602 7970 98.7 1.195 ! Near Maximum !
-02.0 94 26.56 2646 1632 53720 8093 99.1 1.164 ! Near Maximum !
+00.0 96 27.10 2694 1692 57028 8206 99.4 1.133 ! Near Maximum !
+02.0 98 27.64 2743 1754 60540 8307 99.7 1.104 !DANGEROUS LOAD-DO NOT USE!
+04.0 100 28.18 2790 1815 64270 8398
The first group on the bottom row with the low shot was a round that I chambered by releasing a locked back bolt. I could not tell if the round had chambered so I ejected it and once again locked the bolt to the rear. I re-inserted the round into the magazine and let the bolt go forward. That round shot low and the rest shot higher. I will try this charge again and see if it repeats. From what I can tell, there might be something worth testing in the 25 - 25.5 gns of AR Comp.
I am using new brass. The new brass measures 1.190 w my headspace gage and after firing it is measuring 1.199~1.200. I dont think much will change for pressure tolerance with once fired brass. The biggest improvement was definitely adding more neck tension. I will run a quick test with this same neck tension and the Sierra 107 to confirm the poor accuracy was due to neck tension.
As for the point of impact (POI) going lower with increased charge weights is totally fine and this is what happens at short range. Slower loads will impact higher. This statement can be reversed if shooting at longer distances.
My velocity is in line with what quick load predicts for my setup:
Cartridge : 6 mm AR
Bullet : .243, 105, Berger VLD Hunt G7 #24528
Useable Case Capaci: 30.583 grain H2O = 1.986 cm³
Cartridge O.A.L. L6: 2.250 inch = 57.15 mm ****I am using 2.260 COAL****
Barrel Length : 22.0 inch = 558.8 mm
Powder : Hodgdon H4895
-10.0 86 24.39 2448 1398 42272 7542 97.1 1.298
-08.0 88 24.93 2498 1455 44889 7694 97.7 1.262
-06.0 90 25.47 2548 1513 47662 7837 98.3 1.228
-04.0 92 26.02 2597 1572 50602 7970 98.7 1.195 ! Near Maximum !
-02.0 94 26.56 2646 1632 53720 8093 99.1 1.164 ! Near Maximum !
+00.0 96 27.10 2694 1692 57028 8206 99.4 1.133 ! Near Maximum !
+02.0 98 27.64 2743 1754 60540 8307 99.7 1.104 !DANGEROUS LOAD-DO NOT USE!
+04.0 100 28.18 2790 1815 64270 8398
The first group on the bottom row with the low shot was a round that I chambered by releasing a locked back bolt. I could not tell if the round had chambered so I ejected it and once again locked the bolt to the rear. I re-inserted the round into the magazine and let the bolt go forward. That round shot low and the rest shot higher. I will try this charge again and see if it repeats. From what I can tell, there might be something worth testing in the 25 - 25.5 gns of AR Comp.
I am using new brass. The new brass measures 1.190 w my headspace gage and after firing it is measuring 1.199~1.200. I dont think much will change for pressure tolerance with once fired brass. The biggest improvement was definitely adding more neck tension. I will run a quick test with this same neck tension and the Sierra 107 to confirm the poor accuracy was due to neck tension.
As for the point of impact (POI) going lower with increased charge weights is totally fine and this is what happens at short range. Slower loads will impact higher. This statement can be reversed if shooting at longer distances.