Tommygun keyholes

S

Scout

New member
Some years ago, my wife bought me a Thompson M 1. You've probably seen them before; they're a semi-auto copy of the WWII Thompson. Anyway, I finally took it out to an indoor range to fire it. It seemed to work well, except for the fact that the rounds were impacting in a keyhole fashion. They were 230 grain ball reloads. I haven't yet tried any other ammunition, but I intend try some factory stuff soon. Anyone else have a similar experience with this weapon? BTW, the target was at 25 meters.
 
can you post a picture of the target?

also, when was the last time you fired it, and did it work fine then?

EDIT: just read that it was the first time you had fired it. try slugging the barrel for diameter.
 
I would suggest you try a variety of factory ammo first and see if your reloads are the problem. If you're still having problems with factory ammo, you either have a bad barrel, and or the crown.
 
What are you using for bullets? Have you checked the bore?

That gun was designed for 230gr FMJ. If you are using lead or plated bullets going too fast, you may have leading issues.
 
Thanks for your replies. Trying different ammunition seems like a reasonable first step. I threw the target away, so I can't show it to you. I'm also embarrassed to admit that I've never figured out how to post pics here. (Which greatly inhibits my ability to enjoy some threads.) I'll take her out again within the next few days and report back.
 
Thanks for your replies. Trying different ammunition seems like a reasonable first step. I threw the target away, so I can't show it to you. I'm also embarrassed to admit that I've never figured out how to post pics here. (Which greatly inhibits my ability to enjoy some threads.) I'll take her out again within the next few days and report back.
Click to expand...

Upluad the picture to somewhere like imageshack.us or photobucket.com . Then copy the URL it gives you to use and then when you hit reply. Above the reply box there is a little button with a picture of what looks like two small mountains and a yellow background. click that and then put the URL in the box that pops up
 
I have the M1927A-1 version and 230gr shoots OK for me. I don't recall reading about key holing with this fire arm before. Inspect the barrel and maybe call the manufacturer.


M1927A-1
tomgun.jpg.jpg
 
Have you looked at the barrel carefully? It could just be badly fouled, especially if someone fired a bunch of lead bullets through it, without cleaning the lead out.

The gun is intended for 230gr FMJ, and while other bullets ususally work, it seems to be up to the individual gun.

My Tommygun is the Deluxe 19727A1, and while it has a poor trigger pull, it will put 5 shots in a one hole rip at 25yds, and functions with FMJ, JHP, and LRN. Gotta watch the lead though, slugs need to be very hard, or bad leading can result, due to the extra velocity from the rifle's long barrel.

And FYI, mine is an Auto Ordnance, made before Kahr bought the company.
 
I don't know if mine's a Kahr gun or an earlier incarnation. We got it new and unfired about 8 years ago. I have never fired it until recently. I have cleaned the heck out of it and I'm going to try it out again today.
 
OK, a hearty cleaning and some factory ammo seems to have solved this issue. The M1 worked like a charm today. Thanks for all your help.
 
What kind of target were you using? A copy-paper target without cardboard backing will often tear out and leave holes that look like keyholes. I see this most often with the lower velocity large bore pistol cartridges like your 230gr .45acp.
 
Hi. Keyholing is caused by undersized bullets or an oversized barrel and sometimes the velocity.
"...230 grain ball reloads..." Your's or somebody else's? Any idea what it was loaded with? Clean it well, check the diameter of the bullets and slug the barrel.
Almost bought a real semi'd M1 Chopper long ago. Didn't because the way it was semi'd didn't allow putting it on FA to field strip it. Receiver was heavily ground too. Bought a semi'd Winchester M14 instead.
 
If your gun was made after Kahr bought the company, it will say Kahr somewhere on it. I got mine used, and thought it was a Kahr gun, as it came with a manual that said Kahr (and Auto Ordnance). Careful examination of my gun revealed that it does not say Kahr anywhere on it. So it was made before Kahr took ownership.
 
A copy-paper target without cardboard backing will often tear out and leave holes that look like keyholes. I see this most often with the lower velocity large bore pistol cartridges like your 230gr .45acp.
Click to expand...

this is what i was thinking could be the case. which is why i was interested in seeing the target...but since it clearly was a problem related to fouling/ammunition choice, and it has been solved, i expect to see a mod around soon to close this one......
 
You must log in or register to reply here.
Back
Top