I'm going to make a 22LR barrel insert for a 45-70 Rolling Block that I built a few years ago. I hope to make it to a few ASSRA matches this year (which would be my first) and would shoot this 45-70 in appropriate events. The 22 insert would enable me to shoot some rimfire matches as well.

Anyhow, I have no experience with 22 match shooting, and have neither built nor chambered a 22 rimfire, and I notice that there are standard 22LR and Match 22LR reamers available.  My question is, just how tight is a 22 match chamber? and can one chamber your run- of-the-mill bulk 22LR ammunition (Win X-pert for example) in a match chamber? 

I see this as a relatively inexpensive way to get some experience with 22 rimfire competition before deciding to, or deciding what, to invest in a dedicated 22 rifle. 

Any and all help here greatly appreciated.

MM