Have a youth model 870 and would like to swap it for a full size stock.
Prefer wood or laminate.
Is the 12ga stock the same? Can it be modified to fit the 20ga?
I've found some mixed information as to what's needed, some claim they fit both gauges others sell specific for each.
If you have a 'youth model', a 12 gauge stock won't fit it, unless you're willing to modify it at the receiver end, remove wood to fit the stock to the smaller receiver, and refinish it. But it can be done, it's not a problem to make the wood smaller.
Prior to 1977, the 12 and 20 gauge guns were built on a 12 gauge receiver, so the stocks would interchange, Commencing in 1977, Remington finally developed a true 20 gauge lightweight gun, which had a smaller receiver from that point on. The way to tell, is try to put a quarter through the barrel lug. If it fits through, it's a pre 77 standard weight 20 gauge, if the quarter doesn't fit, it's a post 77 lightweight 20 gauge gun. And since Remington didn't make a 'youth' model prior to 77, I'm sure you have a lightweight gun. Incidentally, if it helps, any 742, 760, 7400 or 7600 rifle stock will fit, the receivers on the 20 gauge lightweights are identical to those rifles, and the rifle stock will fit it without any fanfare, that might be an easier way for you to come up with a full size stock.