So today I went out to confirm dope on a known load before a match next weekend. Shooting 6XC, 107 smk's over 39 gr H4350, gives me about 3,000 fps based on ballistic trajectory, and some limited chronograph work. 24" barrel, suppressed.
This is a load I've shot probably 600 rounds of in this barrel with no problems and excellent precision. I've never considered this load terribly hot. But today on the last five rounds on the longest string of fire, about 12-15 rounds at around 1 round per minute, I started noticing a bit of bolt resistance on opening and had ejector swipes on the brass. Fired about 20 total rounds today, and 3 as a zero check the day before, with no signs of pressure.
My assumption of the cause of this is, I started a new canister of powder yesterday, so I'm thinking this lot must be a touch hotter, but maybe it doesn't show up until the rifle is hot for some reason?? It didn't happen when I checked zero with 3 rounds or when I shot 5 rounds at 500. The pressure signs I was seeing weren't bad enough to make me worry about shooting the rounds today, but enough that I'd worry about what I'd get firing 10 rounds in 90 seconds on a stage.
So here is the problem...I think I need to drop my charge a touch, but I won't have an opportunity to do any more dope checking before the match. Targets will be out to 1000+. If I drop the charge by 0.1 gr, will that be enough to likely fix the pressure issue? Pretty sure I could drop a tenth and my dope wouldn't change enough to notice in a match setting.
In this situation, what's the minimum I can reduce the charge by and have confidence I made a difference in pressure?
This is a load I've shot probably 600 rounds of in this barrel with no problems and excellent precision. I've never considered this load terribly hot. But today on the last five rounds on the longest string of fire, about 12-15 rounds at around 1 round per minute, I started noticing a bit of bolt resistance on opening and had ejector swipes on the brass. Fired about 20 total rounds today, and 3 as a zero check the day before, with no signs of pressure.
My assumption of the cause of this is, I started a new canister of powder yesterday, so I'm thinking this lot must be a touch hotter, but maybe it doesn't show up until the rifle is hot for some reason?? It didn't happen when I checked zero with 3 rounds or when I shot 5 rounds at 500. The pressure signs I was seeing weren't bad enough to make me worry about shooting the rounds today, but enough that I'd worry about what I'd get firing 10 rounds in 90 seconds on a stage.
So here is the problem...I think I need to drop my charge a touch, but I won't have an opportunity to do any more dope checking before the match. Targets will be out to 1000+. If I drop the charge by 0.1 gr, will that be enough to likely fix the pressure issue? Pretty sure I could drop a tenth and my dope wouldn't change enough to notice in a match setting.
In this situation, what's the minimum I can reduce the charge by and have confidence I made a difference in pressure?