I have a Ruger Ranch bolt gun. For my control loads I shoot the factory Sellier & Bellot 200gr FMJ. They shoot really well in my rifle. I'm trying to reload some Berrys 220 plated. Experimenting with both H110 and A1680. It seems no matter what I do, the first round out of the 5 shot groups can be 150-200 fps slower than following rounds.
I load 5 cartidges weighed on my RCBS Chargemaster Supreme. When they get loaded in to magazine they are at random, so not first charged vs first fired. it is always....ALWAYS...the first round of the group that is slow.
Not much hair left to pull out......
I've reloaded subsonic 458 Socom before in an AR15 platform and had the first round out of the magazine go to a different point of impact. But charging an AR is different for the first round vs rest of the magazine.
Am I missing something completely obvious, is it dementia setting in....
I load 5 cartidges weighed on my RCBS Chargemaster Supreme. When they get loaded in to magazine they are at random, so not first charged vs first fired. it is always....ALWAYS...the first round of the group that is slow.
Not much hair left to pull out......

I've reloaded subsonic 458 Socom before in an AR15 platform and had the first round out of the magazine go to a different point of impact. But charging an AR is different for the first round vs rest of the magazine.
Am I missing something completely obvious, is it dementia setting in....