[keydet92]

Musser13,
The Model 520 (79013) will have an A suffix to that number and is from around 1922.

The Western Field Model 30 (1309), a store brand Model 520, should have either a C suffix or a U prefix. A “C” gun would be from around 1933 and a “U” gun from around 1935.

Internally these guns are very different. The earlier one has a recoil block in the left side of the receiver and doesn’t unlock after a dry fire. The later gun has the coil spring you noticed that does away with the recoil block by putting pressure on the slide lock release.

I don’t have access to my notes and guns at the moment but I believe both shotguns should use the double lifter spring, the single spring is for the later Model 520A (1940-1949). Can’t remember exactly.

Jack First gun parts is the best source for remanufactured lifter springs.

Here’s a history of these shotguns that I wrote a few years ago that will answer some questions: https://www.gunvaluesboard.com/stevens-520-and-520a-identification-guide-2617.html

 

[keydet92]

Slider,
All the Model 520s (and varieties) had inertia blocks between 1909-1925 (two different styles). In 1925 the inertia block was dropped and a coil spring was added to the hammer pin that puts pressure on a bracket on the side of the slide lock release. This new design was used on all 520/520A/620/620A shotguns and automatically unlocks the action after a dry fire although it sometimes requires slight forward pressure on the action arm in tight guns. If your 520A isn’t unlocking than the spring is bent. The Model 30 is just what Stevens called their base 520s when sold as a store brand.

Musser13,
Thanks, glad you got some use out of it. A lifter spring and sometimes the little lifter pawl spring will usually correct most loading issues as long as the shell stop is functioning.

 

[keydet92]

Musser13,
Someone has used the wrong lifter spring, you need the two-leaf spring. Jack First remakes these and they’re good quality.

The spring that goes in the red circle area is the inertia block spring. No one remakes them but a competent gunsmith can fabricate one, it’s a coil around that pin with a bent end that goes under the post on the inside of the inertia block.

 

[keydet92]

Here’s what the inertia block spring looks like.

Yes, get the earlier firing pin.

 

[keydet92]

It sure sounds like a lifter spring problem. Could you have reassembled the lifter below the spring? It should ride on top of the spring.