I just had a release put in mine, and after reading one of the last post here, I went and put a magnet to the trigger that they sent back, and a magnet does stick to it But not very strongly, so it must be some sort of composition metal, it cannot be complete alum, because like I just said it does attract to the trigger, but just a little.
i had allem's put one in my wife's hi-grade bt-99. yes,he replaced trigger with older type steel one. he is in pennsylvania . i think it cost around 350.00 for everthing. she loves it.he is doing her xt now.
I just removed one from my BT99. I had thought it would have been pinned on, or maybe installed with a small Allen head screw. But, it was actually silver soldered to the top of the trigger. I just simply cut it off and it was all done. Took me maybe 1/2 an hour to bring it back to a pull trigger. It's just too bad that it wasnt installed a better way. Try and see if you can get one installed with either a pin, or a screw, then you can remove it easy if you want to go back to a pull. Steve