I am courious to know how many different forearm slide tubes were made in the 20 gauge. What length variations are there. I found a nice set of wood an the gentleman said his forearm measured 7 3/16 - 7 1/4 from tube nut an to where the collar sets inside of forearm. I measured mine that I have currently an it's 5 3/4. So my question is if they made longer tube variations for the 20 gauge an if so, can I swap out my forearm tube with a longer one an everything still work?

The 20 ga. model 12 began in a chambering for 2 1/2 " shells. In 1925 Winchester changed the chambering t0 2 3/4 ". The magazine tube would have to be at least 1 1/4 " longer to hold the 5 shells it normally holds. Be advised that there were 3 different forearm styles (field grade) during the time model 12's were built.

As far as I know there are only the two different lengths.

You can swap the slide tube for whichever length you want. Finding the right length forearm wood is easy as well though.

Which ever way you go... BE CERTAIN YOU FIND THE RIGHT SIZE SCREWDRIVERS FOR THE MAGAZINE CAP AND FOREARM BAND. They are odd and the screws are easily buggered. The top end of the slide may be rusted in a little, and in that case to want to find a forearm nut wrench as well.

Parts are still available, but no more are being made.

Thanks Guys!!