Thompson 1927A1 Help!

tynman · January 17, 2018, 02:18 PM

Hello everyone. I bought a AO Thompson 1927A1 used rifle yesterday. If what I have read about the serial number the year the rifle was made in 1975 (1 of 937 made that year) This was also the first year they were made for civilian sales. So with that said and out of the way here are my questions and or issues. I know the rifle was messed with cause it is very clear that the recoil springs (at least one of them) is not original and I will order new ones and replace them. (picture 1).

For the first question can anyone tell me what the parts are called in the lower receiver over the trigger? (picture 2, trigger is at the bottom of picture) You can see the worn out metal. I looked at different parts list but I just can pin point which parts they are and I dont want to order the wrong ones. Next can those parts be changed by me or are these pins pressed in that I wont be able to get them out? Would I need a gun smith to do it?

Next I dont have the hold open level on it at the top were the mag loads (picture 3) Would this be normal for this age rifle or did someone remove it and never put it back? What is the part called and can I replace it with a new one again without a gun smith?

I have worked on my other guns so I am able to do some work but I dont have a press.
Thanks for your help

tynman · January 17, 2018, 02:20 PM

2 other pictures if it will help.

**44 AMP** · January 18, 2018, 02:08 PM

I'm sorry I can't help today, my 1927A1 is currently buried in storage, but dig it up this weekend. I agree, something doesn't look right about your lower's parts, when I can compare the pic to mine, I'll have a better idea.

My gun is one of the last AO made before Kahr took over. It came with a Kahr manual, but the gun is Auto Ordnance, doesn't say Kahr anywhere on it.

One thing I can tell you, something I remembered because it seemed unusual to me at the time, the Kahr manual said that if I disassembled the trigger group, it voided the warranty!!

This, to me, implies that there is something difficult or unusual about taking it apart, and while your used gun doesn't have a warranty to void anymore, I'd be very cautious about taking apart the trigger group AT THIS TIME.

The semi auto Tommygun only looks like the full auto on the outside. The entire insides were redesigned to make the BATF happy, and especially to not be interchangeable with full auto parts. One of the results of the redesign is that it takes "three men and a boy" to cock the bolt on the semi, but the full auto can be cocked with just a couple fingers.

Go to the GUN PARTS CORP (Numrich) they should have an exploded drawing identifying all parts.

You do know that original GI & civilian stick magazines need to be modified to work in the semi auto, don't you?

I do want to help, and should have more information in a few days.

tynman · January 18, 2018, 04:51 PM

Well thank you for all that info and any help would be great. I didn't not know the stick mags have to be modified to work. What kind of work is needed?
I did talk to the store I bought it in today and they are willing to have there gunsmith look at it. So I'm going there on Wednesday. So if the trigger group needs any kind of work he can do it... Lol I did see a few videos on a 1928 lower and the trigger group didn't look that hard to put back together. But again if the gunsmith will do it so let him do it. I'm ok with that.

**44 AMP** · January 18, 2018, 09:45 PM

The reason the stick mags have to be modified is due to the redesign of the gun to be semi only. The difference is approximately 1/4". The upper is 1/4" smaller inside than the full auto (as well as the parts being different.

Because the receiver is too small inside to accept the full auto parts, the BATF accepted it as "not readily convertible to full auto".

This same change affects all parts to a degree, including the magazine catch.

The hole in the back of GI mags is just a little bit too low for them to work in the semi auto, because of the slightly different position of the mag catch in the semi. They can be modified to work ok, by making the round hole an oval, removing a little metal from the top of the hole. Its not terribly difficult, but it has to be done precisely, or the mag won't be held in the proper position to feed. The drum mag does not require any modification to work in the semi auto, as it uses a different part of the mag catch to lock in.

The 1928 trigger group (full auto) is a different mechanism than the semi auto trigger group. NOT the same thing at all.

Also, just a word of caution, just because your local smith agrees to look at it, doesn't mean he'll know how, or be able to fix it. He can probably figure it out, with some research, but its not a common gun, that everyone knows inside and out.

tynman · January 18, 2018, 10:17 PM

I hear you on the Smith but they are the store that sold it me so hopefully they will make it right.
With the stick mag the locking hole wasn't the issue it just seemed like the mag was to fat to fit in to slide in and the lip on the mag was to fat too.

Tidewater_Kid · January 18, 2018, 10:28 PM

You at lease have to post a picture of the complete Thompson!

tynman · January 18, 2018, 11:38 PM

Ok here is a picture of her with and without the mag.

**44 AMP** · January 19, 2018, 12:11 PM

I see the two latest pics as the same pic, gun without mag.

DPris · January 19, 2018, 03:54 PM

Parts for that vintage may or may not be available.
Not entirely the same gun as what Kahr's putting out now.
Denis

tynman · January 19, 2018, 04:37 PM

Yes I know but tommy gunner sells the parts for them. And I think they have what I would need.

sorry about the picture mix up. Ill fix it now. Thanks

Dfariswheel · January 19, 2018, 06:55 PM

The damaged part is the Trip.
I don't think that part changed over the production life.

You can change the parts yourself, but it can be a little difficult until you under stand what to do.
The reason why the later caution not to disassembly is simply because people can't figure it out and either get it stuck, can't get it back together, or break the pivot plate which holds the trigger assembly in place and is a spring that powers the safety.

The trigger group can be disassembled just like the full-auto Thompson gun can be.
Gun Digest Books has a Firearms Disassembly on full disassembly of the semi-auto Thompson.

https://gundigest.com/how-to/gunsmit...tions-download

You can probably find something on Youtube.

Going on memory, the early 1927-A1 did not have a normal bolt hold-open.
To lock the bolt open you pull the bolt all the way to the rear, then pull UP on the bolt handle. This locks the bolt open.
To release the manual said to "Ht down on the bolt handle to release the bolt".

Here's a later (1993) owner's manual.

http://stevespages.com/pdf/thompson_tommy_full_auto.pdf

To be clear, standard full-auto magazines can be used in the semi-auto by using a round file to carefully file the TOP of the magazine latch hole in the back of the magazine.
I used a 1/4 inch chain saw file to do this.
You can also alter the magazine catch, and I "think" I remember that you could replace the magazine catch with a full-auto catch.

I'd recommend getting the download linked above and carefully follow it.
The only hard part about disassembly of the trigger group is that the two large diameter pins on the pivot plate tend to bind when removed or replaced.
All that's needed is to make sure you wiggle the plate out while keeping the pins from binding when the plate is allowed to tilt during removal.

All the tools needed are a piece of wood or plastic to pull the safety spring on the pivot plate down so the safety can be removed, and a plastic screwdriver handle to tap the pins on the pivot plate to push them out.
If you do it right, you can remove the pivot plate with just your thumbs.
NO other tools are needed.
There are no springs to fly out easily and get lost.

Unless it's necessary, don't remove the magazine catch. It's easy to damage the coil spring that powers it.

The one recoil spring is short, but to make sure that wasn't something unique to the early models, check the depth of the spring holes in the bolt.
If these are the same depth, the spring was shortened and needs to be replaced.

tynman · January 19, 2018, 08:14 PM

Wow that awesome. Thank you. And with the hold open lever not being there it makes scene with what your saying to pull up on the bolt knob. Because it has a smaller hole cut out right in front of the big hole so that explains that. I will try it tomorrow once I get home.

With the mag I bought I dont know if its a GI one but the lock hole wasnt the problem it was the wings that slide into the groves of the receiver they seemed to fat and a tiny bit to wide but I worked it and removed the paint from them and it go a lot easier. Not like it should be but I can now put it in by hand and remove it by hand. But that I know I can take care of myself. Right now I just want to know and make sure the gun is right and safe to shoot.

The springs I will aslo check to make sure the holes are the same depth and then I will order 2 new recoil springs and replace both of them. But the shorter one looks more like the replacement ones look like the longer one looks thinner. And everything I have read they say the pull back is hard cause of those heavy recoil springs.

Now with the trigger group and parts Im going to bring it back to the store I got it from and hopefully they will order the parts and there gunsmith will put them in for me to make the sale right.

I am glad you said something about the hold open lever because I was very angry that someone might of took the gun apart and they bought it from him and then just put a little oil on it and put a price tag on it, and then just sold it to me without even taking the gun apart and check to see if it was all there. I did find a old military video showing and explaining all part of the gun I dont remember if it was the 1921 or 1928 model and even they had the hold open lever on the front of the receiver.

tynman · January 19, 2018, 08:42 PM

Dfariswheel the part that use to be black and now is wore out and silver now in my picture is what your calling the TRIP?
Cause what I was thinking it was and was called the sear block and sear lever. Is the trip that real skinny part all the way to the right in the lower receiver pictures? Again all the parts manuals are hard to figure out what part is where.

Is the trip in this picture the thing that looks like coin (rounded on top) the trip?

tynman · January 19, 2018, 08:55 PM

I want to know if what is circled in yellow if that is normal ware and what those parts are called? And is what I marked trip and circled in black is the trip? In this picture

tynman · January 20, 2018, 04:14 PM

Well just checked and you are absolutely right about the bolt hold open. It is pull it all the way back and then pull up on the handle... Thank you very much...

tynman · January 23, 2018, 04:13 PM

Well I just found out that what Im looking to replace is a early type 2 piece sear bolt. Now I would like to find one just like it to replace it.

One place I talk to said they would just replace it with a new style one but that can include replacing everything and he couldnt give me a round about cost cause he would need to see it. And to see it, it would cost $70 plus $30 for return shipping. And they guy wasnt to nice about it either.

January 18, 2018, 02:08 PM	#3
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,839	I'm sorry I can't help today, my 1927A1 is currently buried in storage, but dig it up this weekend. I agree, something doesn't look right about your lower's parts, when I can compare the pic to mine, I'll have a better idea. My gun is one of the last AO made before Kahr took over. It came with a Kahr manual, but the gun is Auto Ordnance, doesn't say Kahr anywhere on it. One thing I can tell you, something I remembered because it seemed unusual to me at the time, the Kahr manual said that if I disassembled the trigger group, it voided the warranty!! This, to me, implies that there is something difficult or unusual about taking it apart, and while your used gun doesn't have a warranty to void anymore, I'd be very cautious about taking apart the trigger group AT THIS TIME. The semi auto Tommygun only looks like the full auto on the outside. The entire insides were redesigned to make the BATF happy, and especially to not be interchangeable with full auto parts. One of the results of the redesign is that it takes "three men and a boy" to cock the bolt on the semi, but the full auto can be cocked with just a couple fingers. Go to the GUN PARTS CORP (Numrich) they should have an exploded drawing identifying all parts. You do know that original GI & civilian stick magazines need to be modified to work in the semi auto, don't you? I do want to help, and should have more information in a few days. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

January 18, 2018, 09:45 PM	#5
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,839	The reason the stick mags have to be modified is due to the redesign of the gun to be semi only. The difference is approximately 1/4". The upper is 1/4" smaller inside than the full auto (as well as the parts being different. Because the receiver is too small inside to accept the full auto parts, the BATF accepted it as "not readily convertible to full auto". This same change affects all parts to a degree, including the magazine catch. The hole in the back of GI mags is just a little bit too low for them to work in the semi auto, because of the slightly different position of the mag catch in the semi. They can be modified to work ok, by making the round hole an oval, removing a little metal from the top of the hole. Its not terribly difficult, but it has to be done precisely, or the mag won't be held in the proper position to feed. The drum mag does not require any modification to work in the semi auto, as it uses a different part of the mag catch to lock in. The 1928 trigger group (full auto) is a different mechanism than the semi auto trigger group. NOT the same thing at all. Also, just a word of caution, just because your local smith agrees to look at it, doesn't mean he'll know how, or be able to fix it. He can probably figure it out, with some research, but its not a common gun, that everyone knows inside and out. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

January 19, 2018, 12:11 PM	#9
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,839	I see the two latest pics as the same pic, gun without mag. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

January 19, 2018, 06:55 PM	#12
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,478	The damaged part is the Trip. I don't think that part changed over the production life. You can change the parts yourself, but it can be a little difficult until you under stand what to do. The reason why the later caution not to disassembly is simply because people can't figure it out and either get it stuck, can't get it back together, or break the pivot plate which holds the trigger assembly in place and is a spring that powers the safety. The trigger group can be disassembled just like the full-auto Thompson gun can be. Gun Digest Books has a Firearms Disassembly on full disassembly of the semi-auto Thompson. https://gundigest.com/how-to/gunsmit...tions-download You can probably find something on Youtube. Going on memory, the early 1927-A1 did not have a normal bolt hold-open. To lock the bolt open you pull the bolt all the way to the rear, then pull UP on the bolt handle. This locks the bolt open. To release the manual said to "Ht down on the bolt handle to release the bolt". Here's a later (1993) owner's manual. http://stevespages.com/pdf/thompson_tommy_full_auto.pdf To be clear, standard full-auto magazines can be used in the semi-auto by using a round file to carefully file the TOP of the magazine latch hole in the back of the magazine. I used a 1/4 inch chain saw file to do this. You can also alter the magazine catch, and I "think" I remember that you could replace the magazine catch with a full-auto catch. I'd recommend getting the download linked above and carefully follow it. The only hard part about disassembly of the trigger group is that the two large diameter pins on the pivot plate tend to bind when removed or replaced. All that's needed is to make sure you wiggle the plate out while keeping the pins from binding when the plate is allowed to tilt during removal. All the tools needed are a piece of wood or plastic to pull the safety spring on the pivot plate down so the safety can be removed, and a plastic screwdriver handle to tap the pins on the pivot plate to push them out. If you do it right, you can remove the pivot plate with just your thumbs. NO other tools are needed. There are no springs to fly out easily and get lost. Unless it's necessary, don't remove the magazine catch. It's easy to damage the coil spring that powers it. The one recoil spring is short, but to make sure that wasn't something unique to the early models, check the depth of the spring holes in the bolt. If these are the same depth, the spring was shortened and needs to be replaced. Last edited by Dfariswheel; January 19, 2018 at 07:43 PM.

January 18, 2018, 04:51 PM	#4
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	Well thank you for all that info and any help would be great. I didn't not know the stick mags have to be modified to work. What kind of work is needed? I did talk to the store I bought it in today and they are willing to have there gunsmith look at it. So I'm going there on Wednesday. So if the trigger group needs any kind of work he can do it... Lol I did see a few videos on a 1928 lower and the trigger group didn't look that hard to put back together. But again if the gunsmith will do it so let him do it. I'm ok with that.

January 18, 2018, 10:17 PM	#6
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	I hear you on the Smith but they are the store that sold it me so hopefully they will make it right. With the stick mag the locking hole wasn't the issue it just seemed like the mag was to fat to fit in to slide in and the lip on the mag was to fat too.

January 18, 2018, 10:28 PM	#7
Tidewater_Kid Senior Member Join Date: July 3, 2005 Location: Alabama Posts: 925	You at lease have to post a picture of the complete Thompson!

January 19, 2018, 03:54 PM	#10
DPris Member Emeritus Join Date: August 19, 2004 Posts: 7,133	Parts for that vintage may or may not be available. Not entirely the same gun as what Kahr's putting out now. Denis

January 19, 2018, 04:37 PM	#11
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	Yes I know but tommy gunner sells the parts for them. And I think they have what I would need. sorry about the picture mix up. Ill fix it now. Thanks

January 19, 2018, 08:14 PM	#13
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	Wow that awesome. Thank you. And with the hold open lever not being there it makes scene with what your saying to pull up on the bolt knob. Because it has a smaller hole cut out right in front of the big hole so that explains that. I will try it tomorrow once I get home. With the mag I bought I dont know if its a GI one but the lock hole wasnt the problem it was the wings that slide into the groves of the receiver they seemed to fat and a tiny bit to wide but I worked it and removed the paint from them and it go a lot easier. Not like it should be but I can now put it in by hand and remove it by hand. But that I know I can take care of myself. Right now I just want to know and make sure the gun is right and safe to shoot. The springs I will aslo check to make sure the holes are the same depth and then I will order 2 new recoil springs and replace both of them. But the shorter one looks more like the replacement ones look like the longer one looks thinner. And everything I have read they say the pull back is hard cause of those heavy recoil springs. Now with the trigger group and parts Im going to bring it back to the store I got it from and hopefully they will order the parts and there gunsmith will put them in for me to make the sale right. I am glad you said something about the hold open lever because I was very angry that someone might of took the gun apart and they bought it from him and then just put a little oil on it and put a price tag on it, and then just sold it to me without even taking the gun apart and check to see if it was all there. I did find a old military video showing and explaining all part of the gun I dont remember if it was the 1921 or 1928 model and even they had the hold open lever on the front of the receiver.

January 20, 2018, 04:14 PM	#16
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	Well just checked and you are absolutely right about the bolt hold open. It is pull it all the way back and then pull up on the handle... Thank you very much...

January 23, 2018, 04:13 PM	#17
tynman Senior Member Join Date: December 22, 2012 Location: NJ Posts: 361	Well I just found out that what Im looking to replace is a early type 2 piece sear bolt. Now I would like to find one just like it to replace it. One place I talk to said they would just replace it with a new style one but that can include replacing everything and he couldnt give me a round about cost cause he would need to see it. And to see it, it would cost $70 plus $30 for return shipping. And they guy wasnt to nice about it either.