Thread: ES

Powder charge & type of powder can play a big part in ES. With some powders i have found when getting close to a max charge, ES can start getting quite big & by dropping the charge weight back a bit & sacrificing some velocity, the ES/SD can come down. Not always the case and doesnt always happen at max or close to, but have found that with some powders. If you have been finding your best groups based on charge weight & coming back down in powder charge gives you better ES/SD but worse groups, you can then do a seating depth test to tighten the groups back up.

Brass prep also plays a big part too as mentioned above, especially if its poor quality brass. If you have brass that has a big variance in h20 capacity, this will effect the velocity quite alot with the exact same powder charge. I mainly use lapua brass where i can & its pretty consistent but have used norma brass in one of my old rifles once and ended up having to sort it into 3 different batches as there was quite a difference in weight/capacity across the lot of 60 odd cases that i had.