howa 1500 in .300 problems

[JuanBrno375]

I reside in the RSA and have managed to get my hands on a howa 1500 in .300 winmag early this year. I have put about 200 rounds through it already but been battling a bit to get good groupings iv tried a number of factory loaded rounds and an entire assortment of my own hand loads but still I can't group less than about 6 inches. If there are any other owners out there what will be able to help load data or COL or offer suggestions it will be greatly appreciated.

I'm loading with s365 behind a 180gr sierra game king spbt with a winchester magnum primer in the rear
And
S365 with a 165gr barns sp also with a winmag primer

I know this an old post, but since, new developments have emerged. The synthetic stick is NOT free floated and thus can cause problems. Replacement with a decent stock which is free floated may help in closing the groups. I will be acquiring one soon and if the groups are not close enough. I'll will replace the stock.

 

[Flewis]

I know this an old post, but since, new developments have emerged. The synthetic stick is NOT free floated and thus can cause problems. Replacement with a decent stock which is free floated may help in closing the groups. I will be acquiring one soon and if the groups are not close enough. I'll will replace the stock.

Some of them are short chambered, so watch overall length.