Try 39 grns of h380 under a 50 grn vmax in win cases and cci br2 primer. It offered longer barrel life, could be loaded to different velocity levels while retaining accuracy. It thrives on medium burn rate powders (more on that.
The 52 sierra mk would not be far behind. This load has always shot great in. What's your favorite 22/250 load for accuracy?
My last was a rem 700 vsf. No other consideration, just accuracy. I've had the opportunity to load for 3 different 22/250 rifles. Using bullets from sierra hpbt matchking.
I've been reworking loads for my tikka t3 varmint and the other day i was doing a workup with imr 4895 and a load @ 3,840 fps average shot extremely well, so i loaded 25 of. Using bullets from nosler sp, nosler sbt, hornady hp, speer ssp. Powders include accurate, hodgdon, imr, vihtavuori, ramshot,. Imr4895, in norma neck turned.
I've been using a 52gr.