Assistance With an Addition to my Collection

[Dpedersen]

Welcome to the group!!! Especially glad you found the right Thompson for you!  I’m in the Houston area if you ever want to meet up with another Thompson owner!!!

[Skip Greenwade]

1 hour ago, TD. said:

Skip Greenwade,

Congratulations! Now you need to join The American Thompson Association (TATA) and attend the Hill family Show & Shoot later this year. We have another TATA and forum member that may chime in when he sees you are from Houston. I lived in the west side of Houston for a number of years. What part of Houston do you reside?  

Thanks TD,

I am sending in my application and payment for TATA membership today and will check my schedule in hopes of making the Show and Shoot

I am on the east side of Houston...

Skip

[Dpedersen]

The drive to the TATA show from Houston isn’t that bad, only day and half drive, but well worth it!!! Hope to see ya there this year!

[Doug Quaid]

Congrats on the purchase of M1A1.  I have a 28 and an M1A1 and the M1A1 is sort of my favorite.  I think the M1/M1A1 guns are underappreciated.

Can you post some pictures?

My M1A is an RIA rebuild.  Does yours have any stamps on it?  Any number on the grip frame?

[Skip Greenwade]

6 hours ago, Doug Quaid said:

Congrats on the purchase of M1A1.  I have a 28 and an M1A1 and the M1A1 is sort of my favorite.  I think the M1/M1A1 guns are underappreciated.

Can you post some pictures?

My M1A is an RIA rebuild.  Does yours have any stamps on it?  Any number on the grip frame?

Thank you, Doug!

I agree the M1A1s don’t get enough love. In hand they are pretty impressive.

I‘m almost certain mine was rebuilt as well, as the finish is almost 100%. I don’t see any markings and the lower frame/trigger guard is not numbered.

I‘ll do a post with pics next 

Best,

Skip

[Skip Greenwade]

Pics by request:

 

[rpbcps]

9 hours ago, Skip Greenwade said:

Pics by request:

 

Very nice 👌

Question for the M1 /M1A1 experts.I note Skips M1A1 has a magazine release catch, designed for a drum magazine as well as box mags, so left over from 1928A1 production.

In my collection I have an M1A1 and had an M1, both of which had a '1928A1' mag release catch.

When did Savage and AO, or their subcontractors, start producing specific M1/M1A1 mag release catches, without the raised area that secured drum mags?

[LDog2012]

11 hours ago, Skip Greenwade said:

Pics by request:

 

Nice!

[TSMG28]

According to Frank in American Thunder III, nearly all of the M1’s and M1A1’s he has cataloged had the 1928 mag catches. I suspect there is no documented date when the production line changed over.
I am wondering if most of the mag catches without the drum bump were produced during the extended Thompson production ahead of the M3 switchover, as well as for spare parts that AO continued to manufacture for awhile. 

[rpbcps]

4 hours ago, TSMG28 said:

According to Frank in American Thunder III, nearly all of the M1’s and M1A1’s he has cataloged had the 1928 mag catches. I suspect there is no documented date when the production line changed over.
I am wondering if most of the mag catches without the drum bump were produced during the extended Thompson production ahead of the M3 switchover, as well as for spare parts that AO continued to manufacture for awhile. 

Roger, Thanks for that information.

[Doug Quaid]

On 1/17/2026 at 9:55 PM, Skip Greenwade said:

Pics by request:

 

That's a beauty.  Good job.

I like nice minty armory rebuilt guns.  I think of the rebuild as being part of the history of the gun.  I'm probably the only guy on earth who thinks that, though.

I find the Thompson M1A1 to be probably my favorite gun to shoot. I'm tall and I find that the gun shoulders and points really well, and the peep sight works very well.

We used to have a dueling tree at the MG matches at my gun club and I would crush everyone with my M1A1.  I usually score in the middle of the pack at the actual competition, I move too slow.

Now you got to buy some extra mags and head to the range.  I usually shoot about 250 to 300 rounds when I am shooting full auto, they go quick.  

I am a big fan of getting an complete NOS spring kit for old guns and swapping out the old springs.  Those springs may have been in the gun 50+ years and despite what people say, springs DO get a "set" over time.   Your gun should work 100%, with only very rare stoppages.  It's not uncommon for me to go through 500 rounds without a single failure of any kind.

Just be careful if you take the lower apart, people love to scratch up the side plate.

 

[Mk VII]

There was probably a large 'end buy' of spare parts,  designed to keep the Thompsons serviceable for as far in the future as seemed desirable.   

[TD.]

Excellent advice by Doug Quaid, above, on obtaining a NOS spring kit for your "new" M1A1. I am not a big proponent of changing out the springs just because they are old, but having an NOS set available at the first sign of issues is a great idea. Actually, I would suggest buying two spring kits. One to eventually use and the other as a spare (that you will probably never need). 

The best source for genuine NOS Thompson spare parts including all the springs is forum member Phil Askew. He can be reached at: philfordparts@yahoo.com. Or you can visit with Phil in person at the Hill Family All Thompson Show & Shoot later this year. You will enjoy seeing all the parts Phil brings to the show. 

[Doug Quaid]

Now that I think about it, the only guns that I ever replaced all the springs on are my Thompsons.  Any other time I replaced a spring, it was just a particular bad spring.  So I was not correct when I said that I was a "big fan" of it.  Oh well. LOL

Spring creep is a real thing, but it's not necessarily a problem.

Say that a magazine spring loses 15% of its force in 10 years.  The guy who designs the thing will usually just make the spring 15% stronger to allow for that.

So for that reason a lot of gun guys think spring creep is not important.  And usually they are right.

But when a spring is compressed for a very long time, or is violently "worked", or heated, the creep can get really bad.  I had a 1920's Colt magazine spring that shortened so much that the follower only went halfway up the mag when it was unloaded.  

So guns usually work just fine with old springs.  So I agree with TD's advice to let sleeping dogs lie.

In the case of my two Thompsons, I seem to remember that several of the original springs were clearly very fubar from being compressed for so long, so I figured that I should replace them all.

Recoil springs are definitely a "consumable,"  I must be on my 3rd one in my UZI.  They definitely can shorten up a lot with use.  Not so much with my Thompsons, though.  My M1A1 has seen a LOT of use and the spring is still good.


 

Edited January 25 by Doug Quaid

[Doug Quaid]

By the way, in case anyone cares:

Spring creep is the long-term, slow, and permanent deformation of a spring subjected to constant, persistent stress over time.

Stress relaxation is the time-dependent decrease in stress in a spring while it is held at a constant deformation. 

People sometimes dog me for using the term "creep" as a blanket term, but gun springs are not held in constant strain.

[Rekraps]

1 hour ago, Doug Quaid said:

By the way, in case anyone cares:

Spring creep is the long-term, slow, and permanent deformation of a spring subjected to constant, persistent stress over time.

Stress relaxation is the time-dependent decrease in stress in a spring while it is held at a constant deformation. 

People sometimes dog me for using the term "creep" as a blanket term, but gun springs are not held in constant strain.

THANK YOU for the clarification! I thought Spring Creep was my neighbor peeking in my windows with the nice weather!