This is a little work, but it gives us c&b guys an option w/ slix nipples and CCI #10s.
1. 1/4” OD clear tubing - cut these w/ dykes to make a cap keeper. Cheap for 10’ at Home Depot.
2. CCI #10s are 0.005 smaller than Remington #10s. See Mako’s cap chart. The tubing keeps the caps on and mitigates the not so ideal fit up to slix nipples.