It's about 6 weeks until squirrel season opens here and I got the .32 out for cleaning,oiling and a little dry fire. For dry fire practice on a percussion gun all you need is a plain old rubber faucet washer placed over the nipple. Works great if you are tuning the trigger pull or working on a set trigger.
Rock Lock

heck of a tip there, Rock. Thanks.

Or you can take a plastic valve stem cap off a tire and put that over the nipple. It also works when hunting as a secondary safety and to keep moisture off your #11 cap.

Rock Lock

Guess I stayed old fashioned and used a thicker piece of leather with a hole for the nipple punched in. Plus it absorbs any thing running out of the barrel while in storage...