The stock TM slide will crack if you use propane.
I have had mine crack long time ago, I've replaced all my guns with full metal parts/externals. :kill:
Here's my boring 4.3 with a Creation replacement metal slide and inner barrel. This is my skirmish gun. It's gone through probably close to thousand rounds.
I have another 5.1 which is undergoing surgery, full Airsoft Surgeon build. I will do a write up on it sometime later this year when the final pieces of gold arrive.