I.D. this .22LR chamber adapter

I hope it’s acceptable to post this here.

It doesn’t look like any of the old Marbles adapters I’ve ever seen over the years. Possibly part of an old military sub-caliber kit? There are no markings that I can see.

Thanks in advance.

I’m not an expert here, but that looks like the Hoffer-Thomson auxiliary cartridge used in WWI, in a Springfield with a .22 barrel. Not that rare. See Marcello’s book, “30-06 We Have Seen” Vol III, page 20.

That’s it - I did a search for Hoffer-Thompson and it came right up.

Thanks a million!

Chris–There were two models of the Hoffer-Thompson Adapter. The earlier model had a longer slot in the side and used the .22 Long cartridge. Yours is the later model with the shortened slot so only .22 Shorts would fit.

Want to see them in a charger? Look here
Sorry, you must copy the entire link above and paste it into the browser, it would not allow me to produce direct link for some reason.


Ray, can you please explain why this is not an “Adapter” ?

Does it not “Adapt” a 30-06 chamber to fire a 22RF ?


deleted due to common sense prevailing !



One last comment and then the floor is yours. The Hoffer-Thompson cartridge holder is much shorter than a Cal .30 (not 30-06) chamber and the rifle is 22 caliber. So, it doesn’t adapt anything. A Cal .30 cartridge will not chamber in a Hoffer-Thompson rifle.

You get the last word.


Thanks for clearing this up Rya, so we both agree that it adapts a shortened Springfield M03 chamber to fire a 22Short.

No, I would not agree to that at all. It’s a specially barreled '03 action.

So much for me getting the last word !

Ray is correct. The Hoffer Thompson M1903 Springfield used a special .22 caliber barrel with a shorter chamber to prevent accidental loading of a .30-06 cartridge.

The concept worked okay, and had the advantage of allowing trainees to use the “stripper clips” for loading the rifle when firing on the indoor gallery practice ranges. And, the use of cheaper .22 caliber short ammo.

However, it required special rifles, and fiddling around with the adaptors (or whatever one prefers to call them) to reload them for each use.

In 1919 the Army dropped the Hoffer Thompson scheme and just issued .30 caliber “Gallery Practice cartridges” loaded with a very light charge and a light weight lead bullet, sufficient for use on indoor ranges. However, the possibility existed that someone might accidentally fire a full charge ball round which would be very bad on an indoor gallery practice range.

In 1922, the Army decided the marksmanship training was more valuable than worrying about use of the stripper clips, and they adopted the .22 long rifle caliber bolt action Springfield rifle, Model of 1922, with a five round magazine (similar to most other .22 bolt action rifles). Later variations were the M1922M1 and the M2, with much updating of the early versions to later configurations. These were pretty accurate and popular with rifle teams at the unit level as well as with ROTC training programs and teams. Apparently most (probably all) the .22 long rifle ammunition used with these was from commercial contract sources.

Following the huge purchases of commercial .22 target rifles during and after WW2 the U.S. Army stopped using the Springfield made .22 caliber rifles and just used the commercial guns, and continued to procure .22 long rifle ammo from commercial sources.