Having carefully broken in the barrel on my new R8 6.5x55 I have been developing loads. As is my norm I use new brass at this stage (neck turned) which is then fire formed to refine the load and seating. The conditions for testing were not ideal with a 10-20mph wind which was at least coming over my left shoulder and therefore reduced its effect. I should mention that I fire honed the barrel, very carefully, which I find helps consistency and usually allows a little more velocity without pressure signs.
Powders tested included R19, H4831SC, Vit N160, H4350 & Varget. Bullets tested were Nosler 120g BT and Sierra 140g Gameking. Lapua cases and Fed210M primers. Seating depth 2.5thou. All targets were 5 shot groups.
The Sierras proved easy and N160 was the clear winner as below. The grid lines on the target are 20mm.
With the Noslers, H4350 really came on song between 45.4 & 46.6g. Whilst I have previously seen little correlation between S.D., E.S. and group size the S.D. numbers are impressive. My initial thought was to refine only the 45.4g load, but looking again I think the other loads might all be worth a follow up. Your thoughts / comments would be appreciated.