A common question among TM Recoil owners when looking to increase the FPS of their RIF is “why, or even should I, upgrade my gears?”
The reason why is that they are made from a very soft alloy.
In standard form shooting at 280-300 FPS with an M90 spring this isn’t much of an issue, the last couple of teeth on the sector gear will deform within the first couple hundred rounds fired (as pictured above), but will not wear much further than this for a very long time, as is the reputation of standard TM RIF.
Upgrading even to an M95, which would give you circa 330 FPS, there is a substantial increase in load on the gearset – remember that the motor is not only pulling the main spring, but also compressing the recoil spring.
Pictured above is a sector gear a few hundred rounds after an M95 install, the increase in wear is significant considering such a short running time.
If your sensible and cap the power here at circa 1j / 328 FPS, and do not run high discharge LiPo’s then once again your RIF will serve you for a decent amount of time.
Any higher than this and it is strongly advised to upgrade the gears to save disappointment of a failure during a skirmish or milsim and knock on damage.
However it is not the easiest job on some TM recoils to change the spring, and so whilst inside the gearbox it makes sense to install some gears at the same time, saving on labour costs.
Another benefit of higher quality gears is that most have an enlarged sector delay chip which can be seen below (the elongated crescent mound, LONEX on left / TM on right), this gives the BBs more time to feed into the hop chamber, a nice bonus should you carry out upgrades that would increase ROF.