what are you using for the barrel? I've had a similar project in mind for awhile (mind you, I was going to make it a sawed-off and use it as a sidearm
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*edit* and just to be sure, TM shot shells (and their clones) are the same diameter as Madbulls? I was afraid if I did it that way the bore would be too big or small for the Madbulls when I got them.