300 Win Mag / H4831 / 200 Accubonds test

TackDriver284 · Sunday at 9:59 AM

I had two 1 pound canisters of H4831, one was a quarter full so I switched to the new pounder, and worked up 3 round groups from 74-76 in .4 increments. The new lot is faster by 35 fps and velocities is as shown. Recent test with the old powder at 74 grains was 2914 fps. Seat depth is .020" off the lands.
74 - 2945, 2951, 2963
74.4 - 2966, 2963, 2966
74.8 - 2957, 2968, 2975
75.2 - 2967, 2961, 2954
75.6 - 2987, 2975, 2975
76 - 3005, 3010, 3002
Groups on target is pretty much on a plane, ignore the stray round on 75.6 gr. group because I shifted on the bench. I only see very very faint ejector marks with a magnifying glass on the last 3 three round groups, was not so noticeable so I would not worry too much about it. Tweaked on Quickload and pressure with 76 grains is under max at 3006 fps average.
Not sure which charge to pick to test the last 3 cases i have in the ammo box. What do you guys think? 74 - 75 grains seems to be almost the same average velocity. The 76 grain charge seems good, should I go deeper on seat depth or shallower?
Will anneal the batch of 2X fired 42 cases once the 3 three cases are fired.

Alderman · Sunday at 10:28 AM

I can’t offer any advise but it looks like you have several there that would work just fine.

Hunter26 · Sunday at 10:40 AM

A 200gr 30 cal bullet at those speeds is hauling the mail for sure. It looks like almost every batch had very consistent velocity. I'd back off the 76gr charge since you're seeing ejector marks. Despite what QL says, your rifle may be at its max pressure for that combo. I think I'd play around in the 75.2-75.6 range with a larger sample size or just call it with whichever of the two is more accurate. Shoot at longer distance too.

TackDriver284 · Sunday at 1:10 PM

Hunter26 said:
A 200gr 30 cal bullet at those speeds is hauling the mail for sure. It looks like almost every batch had very consistent velocity. I'd back off the 76gr charge since you're seeing ejector marks. Despite what QL says, your rifle may be at its max pressure for that combo. I think I'd play around in the 75.2-75.6 range with a larger sample size or just call it with whichever of the two is more accurate. Shoot at longer distance too.

74.4 has a pretty tight ES of 3 fps, I may load this and seat another .010" deeper.

jimbires · Sunday at 1:44 PM

I like the ES on the 74.4 load . you have a .020" jump now . most of my AccuBond loads are jumping more than that . I'd try seating deeper , and watch the ES with the shorter ammo.

TackDriver284 · Sunday at 2:57 PM

jimbires said:
I like the ES on the 74.4 load . you have a .020" jump now . most of my AccuBond loads are jumping more than that . I'd try seating deeper , and watch the ES with the shorter ammo.

How deep are you seating?

RL338 · Sunday at 4:05 PM

Each group seems to want to center up at 2’clock. Since seeing a little pressure sign higher up , 74.4 would be my focus point.

jimbires · Monday at 4:07 AM

TackDriver284 said:
How deep are you seating?

my 7mm rem mag shooting 160 AccuBond , I have a .070" jump . I'd probably start at .050" jump and work towards more jump .

TackDriver284 · Monday at 4:30 AM

jimbires said:
my 7mm rem mag shooting 160 AccuBond , I have a .070" jump . I'd probably start at .050" jump and work towards more jump .

I'll try that, thanks Jim

salmonchaser · Monday at 5:43 AM

Not that there is anything wrong with your accuracy I would also like to see what happens with a little more jump. My 338 Jarrett is running 2950 with 250 grain accubonds set .02 off the lands. It did not like more jump. My 300 became 1/2 MOA with .09 jump and 180 accubonds.
I would be very happy with that load given the powder seems to be available now as well.
Good luck.