870 problem ?

[atr]

Last fall i purchased a used 870 in excellent condition and everything worked well for awhile . Now if i slide the action back , it stays back and won't return forward . Press the slide release and it still won't go forward . I took it all appart and gave it a good cleaning and re-assembled it and discovered a strange thing . If i tighten the magazine cap down quite tightly and slide the action back it stays back and won't unlock . If i snug the magazine cap down and then back it off one full turn , the action works .

Any ideas guys ?

It's a police model with a slug barrel . I have another police model with a 14 inch barrel and it works flawlessly .

The magazine cap is supposed to be snugged down finger tight and i don't fancy backing it off a turn and taping it so it doesn't rattle off . Something is jamming inside and the tighter the magazine cap , the tighter the jam . The slide release is spring loaded and seems to work fine pushing it in and out .

I've compared both guns appart and every part is there and nothing looks broken or bent . I haven't tried swapping the action and trigger group from the slug gun to the 14 inch as the 14 is doing exactly what it's supposed to and i don't want it f*cked up for some unknown reason .

I have the AGI 870 Armours video but it doesn't cover much troubleshooting and certainly doesn't cover this problem .

 

[LeePeterson]

It might be a problem with the barrel pressing against the shell ejector causing it to rise in the back and push against the bolt. Try to see if it moves with your hands, or watch it when you tighten down the barrel.

It's only rivited on and the rivets might be getting loose.

 

[easy]

Make sure the slide block is oriented correctly in the breech bolt.
Guide the action bars into the receiver, depress and hold the right shell latch first, then depress and hold the right shell latch at the bottom of the receiver.
Slide the forend rearward until the action bars are stopped by the action bar lock.

Regards.

 

[RePete]

Measure the thickness of the barrel lugs on both barrels, the longer one may be a tad thinner.

RePete.