If you can run a Tok, should be able to run a TCM. Going to depend on ramp geometry how well it works as the rounds are way to the back of the mag. Same issue we have with running TCM on our mag set ups. Toks work great, TCM not so......
Got 2 mags from CMMG last week: 1. Their version of the Mean Arms endo 9mm mag made for their radial delay blow back and 2. One of their 5.7x28 for the same upper.
If you take the spacer out of the back of the 9mm conversion mag, you can put a 22 TCM round in there and we've tested 10 rounds and they work ok. Hopefully this will be an easy mag solution for the tcm.
The 5.7 mag didn't really feed out of the box. The much smaller dia rounds make for a thinner mag ID which don't play well with the TCM. We did some mods and got it to feed OK for the TCM with some real bullets out to about 1.55" oal.