Surefire forend not working on Mossberg 590A1

[WestSider]

Hoping some of you shotgun guru's can help with this one. I have limited knowledge on this. I have a Mossberg 590A1 with a 6 shot tube. Got a Surefire forend from another member on here. The forend SEEMS to fit fine on my 7 3/4" tube, however, when I put it on there and reassemble the shotgun, the action is VERY stiff and clearly not working correctly.

When I switch back to using the stock forend the action goes back to normal. Thoughts? LMK if more information and/or pics are needed.

Thanks in advance.

 

[IndyGunworks]

Is the forend pinching the action bars, causing them to rub?

 

[WestSider]

Doesn't seem like it. I did notice the tube doesn't seem to go all the way into the forearm, due to an extra layer of plastic in it.

In this thread on another forum, this guy dremeled out that part which pushed the tube all the way back into the forend, is this what I need to do?

Mossberg 590A1 *Updated Pictures* - Calguns.net

 

[PGRChaplain]

Go slowly with material removal. Think sandpaper instead of a Dermel tool. Patience is your friend.