Using MAPP gas?

[ThunderCactus]

So I've heard some people like to run MAPP in the cold for better performance than propane.

How much better performance?
What's the minimum temperature you've run it at?
(min temp of propane being in the 5-10 degree range, depending on your gun)
Does it raise your fps at room temperature?
Any added risk to the internals/seals from running the mix of gasses?

[redzaku]

this is for a kj works though, however it does mention that we m4 can run it with no problems
http://airsoftcanada.com/showthread....light=mapp+gas
and this, now if my understanding of mapp gas is sound... the main component, or majority of, is propylene
http://airsoftcanada.com/showthread....light=mapp+gas

someone else on a airsoft retreat forum
"I tested with 2 mags, one with propane and one with propylene, a couple of different ways. I don't have a chrono handy, so I did the PMC to get a range. I tested using my TM P226 with .2g bios and with .25g bios. The temp outside tonight was in the low 70s, and I let both mags warm for 10 minutes prior to each test, and they felt room temp to the touch.

On the PMC, propane puts it right around 290fps, which is confirmed by prior chrono results with that gun. The propylene put it at 340fps+, and I'd guess based on the feel of it that it was right around 350fps.

The kick with propylene was noticeably harder, enough that I think using it full time when it's >70F might cause wear that propane normally would not. Unless your gun is designed for CO2, propylene seems like it would damage the parts that take impact during a cycle. Personally, I wouldn't use it when the temps are above 60F.

The cool down, or lack thereof, was interesting. Normally when I rapid fire a full mag the magazine is cold (not just cool) to the touch, and the pressure drops noticeably toward the end of the mag. With propylene, there was no noticeable drop in pressure, and the mag was barely cool to the touch.

My thought, after trying it, is that during winter when gas guns are problematic, using propylene might be a good way to be able to use your pistol effectively. Between the lack of significant cool down and the higher pressure, performance should approximate that of propane during >70F weather. Using it when it's warmer, however, is not advisable.

We are supposed to get a few nights in the 40's this week. I'll try these tests again when it's cold outside and let you know how it performs."

[ThunderCactus]

Neat.
The smell is something else, the distinct aroma of acetylene mixed with burned burgers and farts.