UC is right about the primer carriers and breech plug , the Metrics Unlimitted plug is a dream come true for that line of ML . Busta did help to design it but you can still find the orange primer carriers on line . The MU plug uses a lowes number 60 O ring which is pretty darn close to blow back free . Ben Hubbard makes a really nice aftermarket ram-rod too should you feel the need for one .

Is the one you are looking at a huntsman or sidekick? Mine, like many others will just plain shoot anything that gets put down the barrel. The trigger on mine is the best trigger I have out of all my guns , just plain sweet.
Steve