Shotgun will not cycle with barrel attached

[Do6]

I store my 870 in the safe with out the barrel on the gun. I tried to assemble the barrel to the gun and the action was very stiff. Disassembled and found no obvious reason. I tried with the original barrel and a Hastings barrel with the same results. The action works fine until the barrel is installed. The rails are straight with no nicks or burrs. Trigger group works as it should. Any ideas ?

[J.R.]

The slide has to be pulled back to the receiver during barrel removal and installation and there is a bit of twist & push to seat and lock the barrel during installation.

Good luck, J.R.