The ROA can use either #11 or #10 caps. The CCI #11 Magnum caps are the identical inside diameter as Remington #10, and shorter -- see the below chart for detail.
I haven't found any noticable difference in shooting performance between CCI 10, CCI 11, CCI 11M, or Remington 10 , although if chrono'ed, I imagine the magnum caps may provide a small additional FPS "kick." Nothing noticable without measuring instruments in my experience, however.
I buy whichever is available and blast away!
Greg
Cap | Inside diameter | Height | Internal Height |
CCI No.10 | .161’’ | 0.163 | .112’’ |
CCI No.11 | .166’’ | 0.165 | .113’’ |
CCI No.11 Magnum | .166’’ | 0.165 | .113’’ |
Remington No.10 | .166’’ | 0.181 | .144’’ |
Remington No.11 | .166’’ | 0.152 | .115’’ |
RWS 1075 No.11 | .165’’ | 0.16 | 0.114 |
RWS 1055 No.11 | .158’’ | 0.2 | 0.112 |