What did you do in the reloading room today?

[Great-Kazoo]

Loaded up some lapua brass w/ some various charge weights of the MR-2000 powder and 178bthp. Shot like junk. We've had no good loads out of this lapua brass and are scratching our heads as to why. Our baseline rifle is SSG3k and that thing went from a 2MOA gun w/ the lapua stuff to 1/2MOA-1/4MOA w/ 45.3gr of rl15 in win brass; atomic factory 175 match stuff shot just over 1/4MOA.

Does lapua brass have to have something special done to it? Has done this with neck size and FL size and had similar behavior w/ rl15. Just weird.

What if anything changed from the original baseline, either load or rifle wise ?

[CS1983]

What if anything changed from the original baseline, either load or rifle wise ?

Only change really is Lapua brass instead of Winchester or similar. Always use 178bthp, fgmm primers, and until yesterday's attempt with some load testing for 2000-MR, powder was rl15. But the Lapua brass has not shot well with either powder. Dunno if we got a bad lot or if something has to be done in addition to the typical prep work we use on plebeian fare brass. Have tried both neck sizing and fl sizing, loading slightly long (2.82) and SAAMI, and tried across ssg3k, tikka ctrx, and ruger rpr. All three guns shoot the other loads and factory match ammo very well, but not the Lapua.