I'm trying the Optimum Charge Weight thing in the M1A now that I have a new barrel (tight! chamber...).
Nosler 155 FMJs, A-Maxes, and Nosler 168s touch the throat at 2.87, 2.88 and 2.89 OAL (forgot which was which), all too long for the mag, so we're jumping at least .07 if loaded to 2.80.
Thought I'd focus the efforts around loads that were reported as good by those of us on the Hide. Well I know every rifle is different and FC brass is a bit softer than others, but I'm beginning to wonder about you bolt-gun guys.
I think it was JL1911 who said 45.5 of H4895 was good with 155 HPBTs. I'm using WLR primers and FC cases--the lightest of several case types I have in stock.
44.9 H4895, Nosler 155s 2963 fps out of my 22-inch barrel, probably too hot.
Chrono picked up only the last of the three 44.9 shots.
45.3 H4895, 2939 fps, too hot (ejector mark, quarter-moon)
45.5 H4895, 2966 fps, too hot (ejector mark, half-moon)
45.8 H4895, 3011 fps, way too hot. (ejector and extractor marks, FLAT primer). Nice OCW spot at 45.3 will NOT be used in this rifle!
Now, this is from a 475-or-so batch of FC I got once-fired from some guys who shot a class with it at about 100 F. The factory loads ALL showed machine marks on the bodies (looked like not-so-polished chambers, like my son's Rem VSS), and slight ejector marks on about half of them.
That's part of why I use them. I believe they are soft enough to show "pressure signs" at 60K, rather than 70-75Kpsi.
So, I'm re-testing with some slightly smaller charges. I don't think you should be able to get 2930 fps out of a 22-inch barrel with that powder.
A previous run without the Chrono had shown promise with 45.5 4064 and the same bullets, so I ran 10 which had been thrown from the Dillon's powder measure. It tends to go +/- .3 grains, for a spread of .6 total.
The two five-round runs were:
Avg. 2882.1 2901.5
SD 34.6 29.5
ES 92.3! 75.2 (still not great)
Looking at 10 instead of 3, made me decide these are probably too hot as well. 1 MOA, I guess you could call that OK for thrown charges.
Then there was the Hornady 155-gr AMax.
43.0 H4895 too hot (sun low on horizon, Chrono went blind)
43.5 H4895, same,
44.0 H4895, same. Strange, but there was no perceptible difference in the slight ejector marks.
The AMax bullet has a shorter boat-tail resulting in a bearing surface about .050 longer than the other 155-gr bullets, but the pressure effect I expected was larger than I expected.
More testing tomorrow, insh'Allah.
Nosler 155 FMJs, A-Maxes, and Nosler 168s touch the throat at 2.87, 2.88 and 2.89 OAL (forgot which was which), all too long for the mag, so we're jumping at least .07 if loaded to 2.80.
Thought I'd focus the efforts around loads that were reported as good by those of us on the Hide. Well I know every rifle is different and FC brass is a bit softer than others, but I'm beginning to wonder about you bolt-gun guys.
I think it was JL1911 who said 45.5 of H4895 was good with 155 HPBTs. I'm using WLR primers and FC cases--the lightest of several case types I have in stock.
44.9 H4895, Nosler 155s 2963 fps out of my 22-inch barrel, probably too hot.
Chrono picked up only the last of the three 44.9 shots.
45.3 H4895, 2939 fps, too hot (ejector mark, quarter-moon)
45.5 H4895, 2966 fps, too hot (ejector mark, half-moon)
45.8 H4895, 3011 fps, way too hot. (ejector and extractor marks, FLAT primer). Nice OCW spot at 45.3 will NOT be used in this rifle!
Now, this is from a 475-or-so batch of FC I got once-fired from some guys who shot a class with it at about 100 F. The factory loads ALL showed machine marks on the bodies (looked like not-so-polished chambers, like my son's Rem VSS), and slight ejector marks on about half of them.
That's part of why I use them. I believe they are soft enough to show "pressure signs" at 60K, rather than 70-75Kpsi.
So, I'm re-testing with some slightly smaller charges. I don't think you should be able to get 2930 fps out of a 22-inch barrel with that powder.
A previous run without the Chrono had shown promise with 45.5 4064 and the same bullets, so I ran 10 which had been thrown from the Dillon's powder measure. It tends to go +/- .3 grains, for a spread of .6 total.
The two five-round runs were:
Avg. 2882.1 2901.5
SD 34.6 29.5
ES 92.3! 75.2 (still not great)
Looking at 10 instead of 3, made me decide these are probably too hot as well. 1 MOA, I guess you could call that OK for thrown charges.
Then there was the Hornady 155-gr AMax.
43.0 H4895 too hot (sun low on horizon, Chrono went blind)
43.5 H4895, same,
44.0 H4895, same. Strange, but there was no perceptible difference in the slight ejector marks.
The AMax bullet has a shorter boat-tail resulting in a bearing surface about .050 longer than the other 155-gr bullets, but the pressure effect I expected was larger than I expected.
More testing tomorrow, insh'Allah.
