I just read the CVA maual for sidelocks and it said all their sidelocks use #11 caps. But I could swear that the guy I bought my Mountain Stalker from said it used #10's. Is there any way I can look at the nipple to find out, or do I just need to buy both and see which fits, or are they the same size, and the difference is the explosive?

#10 caps / nipples are for pistols/revolvers

Your mtn stalker will take a #11 or even a Musket nipple. The thread size you need is 6-1mm

is it possible he put a #10 nipple on it, or just didn't know what he was doing and used #10 caps and it still worked?

most likely just put a #10 nipple on it.

Just order a new nipple for it, they are cheap. Cabelas sells them and even CVA sells them

is it dangerous to just keep using the #10? Is there that much of a difference?

no its just a smaller cap, a little less power from it. Just make sure the nipple doesnt have any broken threads

ok, thanks. About how much should I expect to pay for a tin?

Anywhere from $3.99 to $7.99 is normal

same for #11's if i decide to change it?

I wouldn't worry too much about what the guy told you. Many guys have no idea what size the nipple is.

If the gun has it's original nipple, it should be a #11 size.

My favorite rifle cap is one made in #10.75. Perhaps that's what the guy was referring to.