OP,

It kind of sounds like you're a little unsure of what you're doing. PLEASE PLEASE PLEASE take the time and take the gun to a gun dealer and ask them so they can actually look at your gun before you ASSUME something and accidentally kill yourself.

I've seen guns that have shot the wrong bullet/slug before and it isn't pretty. The barrel WILL spontaneous disassemble (explode) and blow up in your face. Don't take that chance!

Yeah, its pretty basic stuff but people are killed every year accidentally. Don't be one of them. Don't take a chance. Its not worth it. The gun dealer/gunsmith won't charge you for asking them a question. BE SMART!

Best of luck.