Some Thoughts on The Semi Auto Thompson

[Oldtrooper]

Much has been said about the Kahr Arms/Auto Ordnance semi auto Thompson ... I will not debate whether or not the Kahr is a true Thompson, in fact it is not ... But unless you have the means to procure a weapon that cost more than I paid for my first house ... You will have to settle for an Auto Ordnance SA ... There is no SA option beyond that.

The first AO carbine I purchased was back in the 90's ... It was an older West Hurley gun, and I came to one conclusion ... Auto Ordnance must not have had a quality control program when these weapons were manufactured ... From the front sight set off center to the left, to the alternate smooth blue finish that morphed into a sandpaper rough gray steel finish it was a total piece of junk. It kind of brought to mind that old saying about a jeep ... The happiest days in a SA Auto Ordnance owners life is the day he buys it and the day he sells it.

My next attempt was in the mid 2000's when I bought a Kahr Arms Thompson ... It looked 1000% better than the West Hurley weapon finish wise ... Ran about the same though. This weapon however, I sent to PK who I met through this board and he shortened the barrel to a total legal length of 16 inches with the compensator, and did vital surgery on the insides. (This was done so long ago that PK's turn around time was just under a year) Fitted with one of Dan Blocks custom wood sets including the longer horizontal forearm it was a decent, dependable gun. I was thrilled when I received it back ... But once the novelty wore off that 16 inch barrel began to look about five feet long ... It just wasn't right.

I could have bought a Savage 1928 Thompson SMG back in the 1980's from a class 3 dealer in Muncie Indiana for around $3700. A friend of mine had just bought his BAR there and he was encouraging me to buy it ... I passed ... Opting for an M-16 instead. I like the M-16 a lot, but in hindsight as they say ....

Over the years I put together a nice collection of WWII era weapons, with most of the standard US long guns, including an OOW 1918 BAR ... But there was still a hole in the collection with out a Thompson. I decided to purchase another Kahr Thompson and do a short barreled rife to fill the hole.

I made the purchase, and came to the conclusion that Kahr must have at least opened a quality control department ... The outside of the gun was beautiful, both fit and finish ... The insides ... Not so much. Just know this ... Unless you are blessed with outstanding luck, you will have to do some work to make the Kahr Thompson a dependable weapon. The biggest issues with these guns is the feed ramp, and magazine fit.

The .45 ACP cartridge that the Thompson fires has to travel a long way from the magazine to the chamber ... Something around three times the length of the cartridge ... If everything is not just perfect, this is a route destined for problems. The feed ramp on a SA Thompson is different from the feed ramp I looked at on a friends 1928A1 Savage. His FA Thompson has three channels, that I assume is meant to guide cartridges from stacked stick mags and a center channel to accommodate a drum magazine. The SA Thompson has a wide feed ramp that comes from the factory with a very rough surface that will need to be polished to ensure smooth transfer from the magazine to the chamber. Don't attack the ramp with a dremel ... Use polishing tools and work it a bit at a time ... The feed ramp on my Kahr is now as smooth as the polished receiver finish and I experience no failure to feed issues due to a rough surfaced ramp.

The next feed issue for these weapons is the magazines. Perhaps this is the major cause of SA feed issues. The SA Thompson is extremely finicky about magazine height once locked into the receiver ... Most commercially available 30 round mags that have been altered to fit the SA Thompson sit too low and cause double feeds, usually resulting in a popped out extractor from the bolt. Also these magazines are old surplus FA mags that may have weak springs or bent feed lips. In my opinion, unless you replace the SA magazine catch with a FA mag catch, it's best to purchase unaltered mags and fit them to your personal gun. I happened upon a source for some 20 round Auto Ordnance Bridgeport magazines still in the wrapper that once fitted to my gun ran beautifully with no malfunctions. The only magazine that I have never had any fit or feed issues with is an old Auto Ordnance Bridgeport L drum that locks in nicely and functions flawlessly ... It has never malfunctioned. I tried one of the imported L drums and it fit sloppily into my weapon and did have FTF problems ... I got rid of it.

Some other things I did were all internal ... I did some polishing on the bolt and cleaned up rough areas with the trigger ... I also shortened the striker end of my firing pin ... The firing pin on these weapons are very long and are prone to breaking. I removed the same about of steel from the needed areas of the pin to allow the shorter pin to properly strike the primer ... I've fired around 600 rounds with it and experienced no issues. I added one of Dan Blocks EZ Pull spring kits and I now have a very reliable weapon. I also am going to have Dan Block do a barrel replacement with a SMG barrel instead of my "Franken-barrel" ... My son, who is a gun smith simply shortened the factory barrel, crowned it and milled out the compensator to fit the shortened barrel ... Has the proper length but still doesn't look right.

I will add that I don't use the phrase "reliable weapon" lightly ... My entire professional life has involved weapons, as a soldier, and a police officer ... I have to have 100% faith in a weapon that it will not fail me in a time of need or I won't own it. Would I depend upon my Kahr semi auto in a life or death situation? ... Yes. At one time I might have opted for my K-bar over the Kahr ... But with patience and some work they can be made into fun to shoot reliable weapons.

You can see in the photos that the SBR version looks so much better than the 18 inch barrel.

[diff4608]

Very well written.

[Devious6]

Great info here - thanks! I am looking forward to (eventually) receiving my M1SBR once I faiannly have the SN and can process the form 4. The good news is that I live fairly close to the new Tommy Gun Shop.

[ghostsoldier]

I bought mine in the early 2000s', and although I've heard a lot of guys griping about theirs, my Kahr has never given me one day of trouble, and I've run thousands of rounds through it. Maybe I lucked out and got the only good one ever made in those years, but I would trust my life to my M1A1's reliability, any day.

 

Rob

[Oldtrooper]

Great info here - thanks! I am looking forward to (eventually) receiving my M1SBR once I faiannly have the SN and can process the form 4. The good news is that I live fairly close to the new Tommy Gun Shop.

If you have not already paid for your SBR a more economical way to go might be to buy a 16 inch barrel M1 semi auto and apply on a form 1 to make and register a firearm ... Then you might contact someone like Dan Block who could do the barrel change for you, and he might even do the engraving. The Kahr SBR from their factory will have the same issues as their standard carbines ... Unless you get lucky. ... Just food for thought. ... Form 1 wait times are approximately 8 months ... As of January when I had mine approved.

[Devious6]

 

Great info here - thanks! I am looking forward to (eventually) receiving my M1SBR once I faiannly have the SN and can process the form 4. The good news is that I live fairly close to the new Tommy Gun Shop.

If you have not already paid for your SBR a more economical way to go might be to buy a 16 inch barrel M1 semi auto and apply on a form 1 to make and register a firearm ... Then you might contact someone like Dan Block who could do the barrel change for you, and he might even do the engraving. The Kahr SBR from their factory will have the same issues as their standard carbines ... Unless you get lucky. ... Just food for thought. ... Form 1 wait times are approximately 8 months ... As of January when I had mine approved.

 

I have already made the purchase so I'm in for the ride. Through my job, I know the owner of Kahr so I will be able to give him feedback on the rifle and any issues I might have.

[Adg105200]

Nicely written! I don't live too far from the new Tommy gun warehouse either. Always thought about owning a Kahr. Someday I think I will.

 

Andrew

[prozach]

Anybody from these forums who's had years of experience with SA guns want to go work for Kahr, even in a consultant role, to tell them what they should be doing with their guns before they leave the factory?

[dalbert]

Anybody from these forums who's had years of experience with SA guns want to go work for Kahr, even in a consultant role, to tell them what they should be doing with their guns before they leave the factory?

It's already been done with drums. The C-Drums had significant early input, and were good to start off, but things changed after the first 1200 or so...

 

David

[ron_brock]

Great write up. I think the main issue is cost. Kahr likely tries to keep the cost in a range where some people will still buy the guns at a reasonably high volume, however to really be reliable they need more hand fit and finish work. This drives up the cost and would limit the market. I do feel that Kahr has done a great job getting their guns to look much more like the originals then any West Hurley ever did. The limiting factor is still likely balancing the cost versus the market. I think the OOW BAR is a great example. Beautiful guns, but the market is going to be smaller due to the price point. I am not saying they are overpriced, it just costs a great deal of money to make low volume custom guns.

 

After many hours of work and tweaking it sounds like you are well on your way to a great gun. Congratulations!

 

Ron

[Oldtrooper]

Great write up. I think the main issue is cost. Kahr likely tries to keep the cost in a range where some people will still buy the guns at a reasonably high volume, however to really be reliable they need more hand fit and finish work. This drives up the cost and would limit the market. I do feel that Kahr has done a great job getting their guns to look much more like the originals then any West Hurley ever did. The limiting factor is still likely balancing the cost versus the market. I think the OOW BAR is a great example. Beautiful guns, but the market is going to be smaller due to the price point. I am not saying they are overpriced, it just costs a great deal of money to make low volume custom guns.

 

After many hours of work and tweaking it sounds like you are well on your way to a great gun. Congratulations!

 

Ron

Thanks ... My Kahr runs like a fine machine thanks to my son and over a thousand rounds used to break it in ... I got hooked by OOW for one of their 1918A3's .... A fine weapon right out of the box, but not cheap

 

My gunsmith son with the BAR

 

[SHOOTER13]

Fine write up...

 

Guess I got lucky with my AO 1927a1 Commando...

 

 

Circa 2007...$850 OTD Valley Forge PA Gun Show...$200 OTD for the L Drum

 

 

http://i.imgur.com/4OZYHck.jpg

Edited July 5, 2017 by SHOOTER13

[dokkerdam]

I've got a new Kahr Thompson TA5 Pistol. The jury is still out on this one. I've barely got 250 rounds through it and the bolt hold open won't work - let's go right away or with the 'third hand' in it the bolt flies forward once the third hand moves. hmmm. Also, it's aluminum and Dan/Deerslayer told me to look out for the feed ramp area and sure enough with less than five boxes through it there is some gouging. I'm thinking aluminum must have some lifetime limit - I wonder what it is. I'll be calling Kahr about the bolt lock tomorrow and I'll let you know what they say.

dokkersam.

[J.F. Bell]

Semi-auto Thompsons are pretty much a sinkhole for cash. I've owned two, the first being left as a stock 1927A1 and eventually sold, the second being a Commando model significantly worked over for use as a reenacting piece. They can be finicky, problematic, and there's no real justification for owning one besides wanting a range toy.

 

That said, they can also be eminently cool. Even in stock form, a semi Thompson still turns heads most of the time.

 

 

Having installed a Philly Ordnance blank barrel for the aforementioned reenacting purposes, I'm toying with the idea of purchasing a stamp and swapping over a live barrel. In which instance it still wouldn't be a real Thompson, but it'd be an acceptable compromise, I think.