Daystate heavies or H@N Barracuda match work in mine.
Having had six R-10's I have never had a fussy one but grouping always opened up with the magazine. Single shot eliminated any grouping issues and that went for my Scorpions, Ultra's etc.
Another for Bisley Mag and H&N Barracuda Match 4.51 or 4.52. Excellent in all my BSAs
Arte et marte.
Brocock Compatto Target .177 - Hawke Airmax 3-12x50SF
BSA R10se BP laminate .177 - Hawke Sidewinder 10x42SF
Mine used to like the air arms 4.52, jsb exacts 4.52 Bisley mags.
My R10 was useless with any of the JSB/AA pellets but pellet on pellet at 35yards with H&N FTT and H&N Baracuda Match. Although the Baracuda Match are now in tins of 400 instead of 500 so use the Bisley Mags instead. They are equally as accurate. All of the above were best in the 4.52 in my barrel.
Mick
Thanks guys, I knew it wouldn't be long before some sound advice came along