My TMX has under barrel proof mark "AI" indicating that it was proofed in 1982. I bought it used 20 years ago and have never had a problem with choke tubes coming loose. I had an Invector choke Citori where the tubes got loose but I cured that problem with a little piece of teflon plumber's tape wrapped on the threads.
I've had a TMX for years, and they are NOT a heavy gun compared to others. Maybe somehow weight was added to that one maybe. It feels much lighter than something like a Ljutic, Kolar or Mach One for sure. I could never shoot those other guns since I am so used to that light and easily swinging action of the TMX. Like a Ferrari compared to a dump truck compared to some guns.
Bought a racing strip CompIV new in 1978. Was told by some aftermarket
tube makers that the chokes were bad and to have recut. Didn't. Still
shooting it. Keep the tubes clean - don't drop them and watch for dings
on the receiver end. I have a long taper mandrel made that can run in
tubes from receiver end to make sure no dings. If U are in doubt about your
TMX, let me know and will take off your hands.
MIA If the tubes are of the early version with the threads toward the mussel just make real sure they stay tight. Just a little more attention then regular tubes. If they are the later version with the threads toward the breach they need to be tight but you don,t have to be as concerned. No problem at all with that version.