Stevens 620 12 ga Problem

[zerochance]

I have an old Stevens 620 that is giving me fits. The slide lock refuses to release once assembled. It will release, if you give it a good rap from a brass punch, but no reasonable amount of exertion with one's thumb is sufficient. I have replaced the carrier, the lock arm and spring, even the button itself and nothing. I have cleaned up the channel the button rides in to make certain it isn't binding also. I'm stumped. Anyone else encounter this?

 

[entropy]

You have to pull forward on the pump to loosen a lot of the old pumps.....



From the manual Sovblocgunfan liked below:

a (1) (a)).
(b) With bayonet attachment removed, hold gun bottom side up and
press slide lock release which extends through the trigger plate to the
left of the trigger. Then push operating handle forward slightly to allow
lock to disengage, and then pull handle to the rear as far as it will go to
retract the sliding breech. If sliding breech is in forward position, the
extractors will interfere with removal of barrel.

Italics mine.

The rounded end of the sear spring engages the nib on the slide lock, if that's the problem. Easy fix, disassemble and flip the spring.

From the same TM:

In the M620A and M620
Guns, the slide lock spring is of the torsion type and mounted on the
trigger pin and bears down -upon the rear end of the slide lock. In the
M520 Gun, this spring is of the safetypin type and seats in a hole in
the top of the left wall of the trigger plate, and bears upward on the
rear pin of the slide lock link positioned in the forward end of the slide lock.

The pictures on page 74 are hard to see, but you can make out the spring behind the slide lock, and see the nib the spring engages. I used to hate when these came into the shop, the actions would always have 40 years of lint, weeds, and grime in them.

 

[Sovblocgunfan]

Check to see if you spring is assembled incorrectly. I did mine that way once and locked up the gun. This manual should show you the correct orientation-look for the 520-should be same.

http://usacac.army.mil/cac2/cgsc/carl/wwIItms/TM9_285_1942.pdf

 

[zerochance]

Okay. It wasn't the spring but having taken a bit of time away from it, it appears that the outer edge of the slide lock has been rubbing against the inside of the receiver. Not sure at this point what is causing the misalignment - But solving that would seem the reasonable next step.

Thanks all for the help, sometimes I just need a push to get me to see past my current hang up.

 

[entropy]

Make sure all the trigger group parts are slid in to where they belong on their pins, and that the pins are not sticking out too far on either side.