less than full mag's gas
 

Yesterday was the first time I took my KJW M9 to a game. It did what it sometimes did at home: ran out of gas with 3-4 BBs remaining and the last few shots before it ran out I'm sure didnt make it to my target. I'm sure this has happened before but my search terms arent comming up with anything useful. Any tips?

Outdoors? Oiled? What gas and how did you fill the mag?

yeah all oiled up prior to the game, but the slide may need a bit of grease. Using propane. Indoors. The guy loading the mag for me had it sitting on top of the heater for a minute or two before he filled it, which is opposite to how I would have thought (cooler = better for filling?). I made sure the mag was well oiled and not leaking before I went.

I'd stay FAR away from anyone who would put a GBB mag on a heater... that has to be one of the most stupid things I ever heard being done.

Charging it with gas while cool will allow more liquid gas to get in. Warming it with your hands after, or if used indoors at normal house temperatures, is enough. Heating it is... dumb.

Heating it before filling is better than microwaving it after filling.

maybe thats what he did...I didnt see him actually fill it so maybe he heated it up a bit on the radiator before going off and chrono'ing it

Okayyyy.... how to put this in simple terms?

Green Gas = Propane = flammable or explosive volatile substance. Would you heat up a propane tank?

Heat + propane + solid container = grenade

Grenade + hand = messy

Okay for the basic high school physics course?

Grey, the mag was empty before they put it on the heater, warmed it up that way, then put the gas in after taking it off. Nothing wrong with that, well, aside from not needing to warm it prior to filling............

Anyways................

Possibly have something to do with the rate of fire and cool down? Happens with my Beretta in colder temps. Last bit of gas is cool enough that it doesn't exert enough pressure on the release valve to keep it closed. The slide doesn't blow back all the way and the "hammer" just rests on the valve...venting the remaining gas.

Okay, so try to fill a hot mag and see how much (little) gas it will take. That explains running out of power.

And it also shows that the person running that place is clueless. Everyone who has the minimum of info about GBB use indoors (as in this case) will know better.

ok it worked beautifully last night. So it COULD have just been the colder temps in the arena the night before. I dont really know how he filled it or anything. The mag had been sitting out in my truck at -20 for a few hours, he might have been warming it up a bit before filling so he could chrono it at closer to playing temps.

And a hot water radiator is hardly ignition temperatures...you can hold your hand on it comfortably.

It also could have been an honest mistake, but those never happen now that the internet is around, right? We have to instantly call the person clueless or stupid according to unwritten message board protocol. :roll:

I've put filled GBB mags on a small heater for a short time to get them warmed up to room temperature more quickly before a game, especially if they've suffered a lot of cool down from a prior game. You want your mags cold when filling, warm when shooting.

Greylocks' fearmongering aside, propane autoignites at 468C. I sincerely doubt consumer-grade electric heaters (especially the ones at XT) are going to pose a fire hazard. If it won't ignite paper (autoignition 233C), it certainly won't ignite propane. Regardless, if you use one to warm up a GBB mag do NOT leave it unattended and pay close attention. The hotter the gas gets the more velocity you'll attain which could possibly put your gun over the field limit, potentially causing injury. It will also cause accellerated wear on your mag and gun from the higher pressure.

More than likely your problem is the mag isn't being filled to capacity. If your seals are properly lubed have someone knowledgable strip the mag apart and see if they can find anything internally that may be causing the problem. Otherwise you probably need to buy a new mag. The advantage of KJ guns is they're directly compatible with Marui and HFC mags of the same type, so you have a lot to choose from.

The risk isn't autoignition, the risk is pressure building higher than the valves of the mag can take.

As harleyb just said. The type of heater was not specified, so the answer was the worst case scenario.

Keeping a charged mag at -20 for hours will mean the gun probably wont work at all. No GBB works well (or at all) in cold weather.

A simple and safe solution is to keep the mag in a coat or pant's pocket so that your normal body heat keeps it warm enough. No more is needed.

True enough, and I hope no one took my post as a recommendation to heat mags on heaters. As a field expedient ONLY I don't see it being a major issue. Especially at Xtreme Tactics, you may come out to have your mags refilled and gassed in the middle of the game and need them warmed up quickly because you're paying for your time in the facility.