We get a lot of orders for the 22 TCM 9R to convert their 9mm blow backs for use on Glock Lowers…… and a lot of disappointment from the caller when I tell them, ” You can’t do that.”
But the 5.7×28 works in blow back… yes it does.
The factory TCM brass is soft. If you reload it you will find out how soft it is, and I believe that is a contributing factor to the case head separations. Therefore, we don’t build blow back TCM’s. The DI version works great, but you need a magazine to feed it.
We have been working with the TCM for years and our first tests were for a customer wanting to build Blow Back systems for the TCM. Of course we built test units and quickly blew things up with multiple case head separations and worse. We told the customer, and they didn’t care, they wanted the barrels, they could fix it. They called back and said the TCM’s were blowing up, what was wrong with our barrels…… ( we do have reports of converted 556 brass being used in BB with success, but we do not recommend it)
The Glock Lower: You can make a Glock lower cycle with a DI upper, but you need to add the “Glock Cut” to the BCG and removed the stock BB Ejector (PSA / NFA style lowers). In the name of science, we have done that and have 100% functioning TCM-9R uppers running stock Glock mags.
TCM mag Lower: So also in the name of science and BRD, we cut a Glock Lower to accept a std TCM mag. Again, you need to cut the BCG accordingly and other mods. Its a pretty simple machine cut to a PSA or NFA Glock lower as the mags “almost” fit. To get them to drop free, it takes some file work.
I hate to say this, but the TCM ran 100% on our test upper. I took a new Upper and put it on the TCM lower for testing to see if it would make a difference….
and again,,,, it ran 100%.
The “problem” is that you need to cut a mag slot in the TCM mag for this to work and its right at the point where it opens up the stock TCM mag slot which would cause and issue with your TCM pistol / rifle.
To eliminate that would take a dedicated TCM lower / mag release.
The next test was putting a stock 9mm mag in the TCM modified lower and, while a bit (more) sloppy, it ran the 9R ammo. I have not tested on a BB 9mm to see how that goes..