Hammering a barrel onto the mag tube / receiver. Will it be OK?

[Scorpion8]

It's seated all the way back now. Do you think it will be OK for a test fire?

The barrel should be fine, especially since some police 870's are used in breaching operations. The mag tube was what you bungled, so I'm thinking you'll be okay.

[BKinzey]

My guess would also be possible feeding problems. Does it cycle ammo well?

Using a rubber mallet greatly reduced your chances of doing damage I think. Of course since the internet, I've seen determined people do a lot of damage with very little.

You should be fine. May need to use a small brass/ plastic mallet and a brass punch to tap it off though.

[Banshee]

You MAY be able to shrink the tube back by using a 1 inch steel scope ring. Place the ring around the damaged section and tighten the screws a little at a time. Start on the outer most damaged area and keep tightening, loosening and slowly work the ring up the damaged area.