I enjoy strange and unusual projects. What is more unusual than a bolt action rifle chambered for a pistol cartridge? While it has certainly been done before, for instance the 45 ACP De Lisle carbine from the Second World War, it is anything but common. Pistol cartridges have a unique set of challenges in a bolt action rifle; the are harder to feed and extract and they require a very short magazine.
The Armscor M22 TCM BA rifle, manufactured in the Philippines has proven to be an effective host for the 9mm pistol cartridge. One, now defunct gunsmithing company, had offered conversions of this rifle from 22TCM to the 9mm Luger. I’ve been looking forward to tackling a project like this for years but supply issues and time have often gotten in the way. The rifles aren’t always available from distributors and the few I’ve purchased for projects have been purchased at my store before I got around to working on them. Recently I was fortunate enough to carve out the time to convert one. This is how it turned out.
Why convert the Armscor M22 rifle? This is mostly because of the unique nature of the rifle’s design and its relatively inexpensive price point. The one I tested didn’t shoot particularly well in the 22TCM, it is an interesting rifle that has a fairly robust construction. While most of its contemporaries have moved completely to injection molded plastic parts, the M22 retains mostly metal parts with a nice hardwood stock. Beyond these basic qualities, the rifle feeds from a pistol style magazine, one that will fit the 38 Super cartridge (a longer version of the 9mm) and has a bolt face that is appropriately sized for 9mm. These features make a conversion fairly simple and straight forward.
Before we begin looking at how the conversion took place, please take a moment to read the following disclaimer:
The contents of Rifleshooter.com are produced for informational purposes only and should be performed by competent gunsmiths only. Rifleshooter.com and its authors do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.
Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.
Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.
For this project I ordered the following parts from Brownells:
- Stainless steel 9mm AR 15 barrel
- 9mm go and nogo gauges
- 9mm reamer
- Barrel vise
- Universal action wrench
- High-speed steel turning tools
I begin by breaking down the rifle. The M22 is assembled a little differently from most bolt action rifles. The bottom metal assembly and trigger guard are attached to the barreled action (above) and then retained in the stock by a pair of action screws. This means the action and bottom metal, more or less, float on top of the stock.
To remove the factory barrel, I use a barrel vise and universal action wrench. I keep my barrel vises (I use a Farrell and Brownells depending on what the job is) in a Harbor Freight 20 ton shop press that I added a pneumatic jack too. This makes the chore of tightening a barrel vise quick. The barrel wasn’t particularly tight to the receiver.
The barrel tenon on the TCM 22 is fairly unique. It is long for its diameter and has a step down with a smooth shank at its breech end.
The action has a relatively small outside diameter. Note the universal action wrench below it. This is what I used to take it off.
Originally I had planned on machining the new barrel from a straight blank, but it seemed like most of these conversions had been made from 9mm AR 15 barrels. This seems to make sense since the tenon you need to cut is significantly smaller than the tenon on an AR15 barrel and the finished outside-diameter of a 9mm AR15 barrel would work well in the M22 stock.
A lathe is required for this job. I’m fortunate to have the excellent Precision Matthews PM-1440GT. This is a precise lathe that is marketed to gunsmiths. I love mine.
I begin by dialing in the barrel on the lathe with a set-tru 3-jaw chuck. This type of chuck allows adjustments similar to a 4-jaw. Any real machinist reading this post would likely cringe when he sees the work set-up as it is above, the tenon is really father away from the chuck than it should be; but I have no doubt that I can take light passes and make this work. 9mm AR15 barrels don’t have a barrel extension (at least this one didn’t). That allows you to machine from the very end. It does have an indexing pin that is pressed in. I wasn’t able to remove the pin because it was too tight. I decided to cut the rear tenon down behind the pin so I could relieve it and slide it out of place.
I used high-speed steel insert tools from Brownells to machine this barrel. The high-speed steel cuts stainless very well at manual machine speeds. The tenon dimensions were taken directly from the factory take off barrel. I decided not to post them here since I am not sure how consistent they are from gun to gun.
Thanks to some careful measurements, the barrel head-spaced perfectly without a need to deepen the existing chamber!
The barrel is tightened to the action using the same barrel vise and action wrench as before. I make sure to verify that the headspace is still correct.
The profile of the new 9mm barrel is slightly larger than the factory barrel. This means the stock needs to be inletted slightly.
I used a shallow gouge to open up the channel.
The M22 has a steel feed ramp that is screwed to the bottom of the action. In its factory configuration, it will not allow 9mm rounds to feed.
I polished the ramp back with a round file followed by some abrasive cloth.
Now the 9mm cartridges will feed. You can see this in the image above when all the parts are held in alignment.
The finished rifle looks fantastic. It cycles 100% of the time and has very little recoil, uses inexpensive 9mm ammunition and turns heads at the range. The only downside is that it isn’t very accurate. I suspect this is because of the inexpensive barrel that I used. At 50 yards, most of the ammunition I fired through the rifle key-holed. I plan on re-barreling this rifle with a different barrel to see if this improves.