Recoil spring wear - when to replace.

[reconbob]

     I had a guy in the shop today that had questions about recoil springs and how to know when it is time to replace them. For some reason he thought that coil springs never show wear. This is incorrect. Coil springs ALWAYS show wear, but with a Thompson recoil spring it is a more subtle thing to recognize.

Here is the recoil spring from a Browning Automatic Rifle showing obvious wear by the flattening of the coils of the spring. It's not a great photo but in the middle of the picture you can see the coils are noticeably flattened.

Here is a Garand recoil spring - same situation - the flattened coils are obvious -

Not so easy with a Thompson but it still happens. Here is a new recoil spring -

And here is one with the flattening of the coils, but not as obvious as BAR/Garand because on the Thompson the diameter of the wire is a little smaller. But it's there - the easy way to recognize it is to compare the flat coils in the middle to the round coils in the corners of the photo.

So yes, coil springs always show wear and eventually wear out. The best/easiest way to check a Thompson recoil spring is to measure it. It should be 11 5/16" +/- 5/16" long.

Bob

 

 

[Stampcollector]

Great post Bob!

I will look closer to all of mine.

Stampcollector 

[LDog2012]

This is super helpful. I never had a clue about spring wear in either the Garand or the Thompson. Thanks for posting. 

[PK.]

As i recall, the GI Manual says to replace the spring at 10 1/4" or shorter, or if it's kinked.

[68coupe]

As always, a wealth of knowledge. Thank you.

Karl, 68coupe

[Merry Ploughboy]

The good news is, I don't believe that I can afford to buy enough ammo to wear out the recoil spring.

The bad news is, I don't believe that I can afford to buy enough ammo to wear out the recoil spring.

[Stampcollector]

58 minutes ago, Merry Ploughboy said:

The good news is, I don't believe that I can afford to buy enough ammo to wear out the recoil spring.

The bad news is, I don't believe that I can afford to buy enough ammo to wear out the recoil spring.

That's funny,  😆 damn!

Thanks for that 👍