Hello folks i have a 870 20 gauge "lw" (factory twenty gauge nowadays)

it is not a magnum receiver... and the barrel I want to buy can shoot 2 3/4 and 3" shells...

I want to know if I put a barrel that will shoot 3 inch shells mess up my receiver in anyway?

Is it the barrel or receiver that makes it a magnum...

The "standard" receiver was based off of the 12 gauge receiver and the "lw" was milled down to make it lighter. The "standard" receiver was eventually dropped for the "lw' or factory receiver they make now.

I believe either will shot magnum shells but I don't think the barrels are compatible between the two, Though newer barrels should fit the "lw" receiver.

I could be totally off on this, you might want to drop a line to Remington to confirm it.