Sorry for the delay Duct Tape, had some RL things that drew my attention for a few days.
Darklen is right for the most part. Gas replicas, GBBs are numerous and there are a a bunch of companies that make them. KWA and KSC are probably the ones with the largest line of GBBs. I do not own a pistol from either, though I have heard good things of both, but only from specific models. Some though, are gas hogs, and use way too much. I use Green Gas in my 1911, which is basically just propane with silicone oil. 134a is another much used gas but can result in a gas replica shooting too hot and is much more susceptible to climate changes, so I stick to Green Gas. HFC makes a lot of clone gas pistols, but I personally know nothing about that line.
As Darklen said, the TM Glock has an ABS slide. A lot of people go nuts ove rABs and hate it, as TM uses ABS in most of their replicas (one reason some people prefer CA as they use pot metal for more realistic weight), but as for durability, ABS will only break if you run over it with a tank. For a guy my size I'm fairly active and have bashed, dropped, thrown and slammed my stuff against pavement, trees and other people and never had anything break, so don't let ABS worry you.
As for AEPs, like my CYMA Glock, there are mixed feelings. Darklen doesn't like them it seems and I don't blame him. Many of them just don't feel right using and GBB feel more realistic, but if you're on a budget, or don't think you'll be using a sidearm much, I would suggest an AEP. CYMA and other Chinese manufacturers have increased their quality control as of late and have been manufacturing better replicas at competitive prices that some people choose over the brand names.
However, first I'll point you to the guys who I've done almost all my business with for the last 3 years. They just added (18 months ago or so), after popular demand) the lines of various clone companies for those players on a budget. And don't let the word 'clone' scare you or anyone away, it no longer holds a derogatory nature. Technically, I consider all companies, for the most part and with few exceptions, clone companies of TM as they did most of the R&D for years and years for the sport.www.trinityairsoft.com
Hopefully I'll have some more pics up soon along with a few more posts to supplement stuff from Jack.
As for force on force I have, for 10 years or so, 'played' Airsoft with others. If you want to think of it as playing guns or whatnot, that's fine and not uncommon, but every group I headed up treated it with respect and seriousness. Something else I'll post on later I think.
I've gone to ACQB in VA and played with LEOs and current/former military personnel and would like to begin working with local PDs, not only because they need the help and experience but because airsoft has a dubious present and future and as a player I feel it's a duty to make it possible to keep the sport alive and healthy for later, and so good must be done to outweigh bad.
Hope that answers some questions, and sorry for the delay again.