TM-1's are at the top for best handling most reliable and best value of any single shot shotgun ever produced. Unlike the taller MX series that has two firing pins to fire either a single or over and under barrels the single barrel TM-1 has a lower profile enhancing the guns movement.
Much better trigger in the TM. No slack and much less complicated in that it does not have to reset for a second barrel. Thankfully most TMs came with a coil spring trigger. The early TMs, below about ser# 900, had the leaf spring. Marc
All I can say is that the first two TM's I bought and the one my Dad bought, all serial numbered under 900, were leaf spring triggers. I have bought a couple of used TM's since, all low ser# and leaf spring. Coil may have been an option on early guns I was not aware of. As far as I know, later TM-1s were all coil spring. The newer TM-9's can be had either way.
Nothing wrong with the leaf spring versions except they break at the most inopportune time, although rarely but right when you need it most. I shot on a long yardage squad that had two P-guns with leaf springs fail during the same 100 bird event.
You mentioned your gun has coil springs. A TM has only one spring. Could your gun be an early MX or Comp-1?
Marc I ment spring as in singular, Chris you would be the first person I know of who can tell the difference between a coil and leaf spring trigger especially in a Perazzi. A coil trigger is by far the most reliable of the two and is the reason Perazzi started offering them in their MX series.