So I just swapped to a 6.5 CM barrel for my LMT MWS. 20" SS with 1/8 twist. Started working up a load using the satterlee ladder test. First time trying this and I usually do OCW.
Components:
Starline small primer brass
Fed 205M primer
H4350
Sierra 142gr SMK
COAL 2.815"
Charge and velocity as follows:
1) 41.0 - 2695
2) 41.2 - 2716
3) 41.4 - 2720
4) 41.6 - 2726
5) 41.8 - 2747
6) 42.0 - 2755
7) 42.2 - 2755
8) 42.4 - 2767 (blew out the primer so I stopped here)
Looks like I have a pretty wide node between 41.2 and 41.6 grains. So I loaded up 5 rounds with 41.4 grains and got the following chronograph numbers:
MV = 2717
SD = 9
ES = 22
I had one flier that made the group 1.13 MOA. Without it the 4 shots were 0.66 MOA with 3 rounds through the same hole. So it looks like this is a winner.
Now two questions/problems. First, I had loaded up a few rounds with 40gr of powder to use as sighters. All other specs were the same and I got the following chronograph data from 10 rounds:
MV - 2677
SD - 6
ES - 23
Didn't measure the group size but it was >1 MOA.
Second, every single one of the rounds I fired from 40gr up to 42.4 gr had some primer cratering and most had some ejector swipe. The primers were not flattened and the edges were definitely still rounded.
I shouldn't be over pressure on the lower charge weights I don't think. I even shot some hornady factory ammo to check if maybe the velocity was excessive for my barrel. It was hornady black loaded with 140gr BTHP and I got a MV of 2657 FPS and no primer cratering or ejector swipe. The factory ammo had large primer pockets though so I'm wondering if this is normal with small primers.
So do you guys think I could be over pressure on the 40gr and 41.4 gr loads? Is there anything else that could be causing the cratering and should I be worried? I sometimes get ejector marks when I'm shooting the .308 barrel with the LMT but it doesn't look as bad as this. I can attach pics if that would help
Second, what load would you use based on the date? Both will stay supersonic out to 1000 yards which is as far as I'm going to be shooting.
Components:
Starline small primer brass
Fed 205M primer
H4350
Sierra 142gr SMK
COAL 2.815"
Charge and velocity as follows:
1) 41.0 - 2695
2) 41.2 - 2716
3) 41.4 - 2720
4) 41.6 - 2726
5) 41.8 - 2747
6) 42.0 - 2755
7) 42.2 - 2755
8) 42.4 - 2767 (blew out the primer so I stopped here)
Looks like I have a pretty wide node between 41.2 and 41.6 grains. So I loaded up 5 rounds with 41.4 grains and got the following chronograph numbers:
MV = 2717
SD = 9
ES = 22
I had one flier that made the group 1.13 MOA. Without it the 4 shots were 0.66 MOA with 3 rounds through the same hole. So it looks like this is a winner.
Now two questions/problems. First, I had loaded up a few rounds with 40gr of powder to use as sighters. All other specs were the same and I got the following chronograph data from 10 rounds:
MV - 2677
SD - 6
ES - 23
Didn't measure the group size but it was >1 MOA.
Second, every single one of the rounds I fired from 40gr up to 42.4 gr had some primer cratering and most had some ejector swipe. The primers were not flattened and the edges were definitely still rounded.
I shouldn't be over pressure on the lower charge weights I don't think. I even shot some hornady factory ammo to check if maybe the velocity was excessive for my barrel. It was hornady black loaded with 140gr BTHP and I got a MV of 2657 FPS and no primer cratering or ejector swipe. The factory ammo had large primer pockets though so I'm wondering if this is normal with small primers.
So do you guys think I could be over pressure on the 40gr and 41.4 gr loads? Is there anything else that could be causing the cratering and should I be worried? I sometimes get ejector marks when I'm shooting the .308 barrel with the LMT but it doesn't look as bad as this. I can attach pics if that would help
Second, what load would you use based on the date? Both will stay supersonic out to 1000 yards which is as far as I'm going to be shooting.
