If it ain't broke, don't fix it. Try the gun out with light & heavy loads. Remington #10 caps are what I use on all my guns. If you need to, the CCI#11s are close as is the RWS#1075. Some of my guns thake the RWS and others take the CCI but ALL take the Rem#10. I have a lot of Uncle Mikes nipplew in my guns. If the nipples vary in size THEN replace them 'cause you'll go nuts trying to match different caps for different nipples. If only ONE nipple is off sized then let it be the open/unloaded chamber. If you need nipples, get them at Thunder Ridge Muzzleloading supply. The stainless nipples are like the old Uncle Mikes/Butler Creek replacement nipples. The Treso nipples are a little better but a little longer. Both makes take the Rem#10 cap. The factory nipples generally have larger flash holes and you can get more blowback of the hammer leading to cap jams. This is a bigger problem for Colts but happes with remingtons too. My Uberti Remmies have factory stock nipples and they handle all level of loads up to 30grs under a 200gr conical.