Inconsistency?....Help?!

[cavninja]

I am deeply devoted to GBB, I love the realism and the functionality, it's as close as it gets! I love my WE HK416 and have lovingly tweaked its barrel and the hop and fitted and NPAS, as it's natural position is to run a "tad" hot!

However, I do find that the mags a quite inconsistent, depending on the ambient temperature, the amount of gas in them etc.

Is this just the natural way with gas mags?

I've got my NPAS and hop set to shoot at about 330 fps and I do find that prior to chrono-ing, it's a good idea to run a mag or two through my gun to settle it in.

I use WE green gas, would propane be more consistent as well as cheaper?

I don't have these issues with either of my pistols.

I regularly use maint. gas and never leave my mags un-gassed, all my kit is new and less than six months old, so any advice or tips would be greatly appreciated.

[M_P]

Green gas is propane so using propane will save you some money straight off.

It's natural, gas's pressure is temperature dependant so as the weather changes etc the power output will change.

[cavninja]

Cheers MP, i figured as much, it's all Charles's law and Boyle's law, but i do get some wildly varying fps's, until the mags and temp bed in.

I must get round to getting a propane adapter and saving some of my hard earned pennies!

[M_P]

Yeah it's something like that, been a while since I did physics

[Russe11]

FPS will depend upon the following factors:

Gas pressure (depends on the temperature)

Release valve: Stronger spring means it will depress less lowering fps, it may also be stiffer at the beginning of the day. Keep it well lubed.

Hammer/firing pin or whatever you want to call it: Keep it well lubed as how hard it hits the release valve will also affect fps.

 

I am fortunate in that my gas powered SMLE is bolt action and therefore a lot simpler, but it was very inconsistent out of the box. In fact it was so inconsistent that sometimes it wouldn't shoot if it was too warm as the gas pressure would prevent the firing pin from depressing the release valve enough. The solution was to add washers to the spring on the firing pin so that the release valve is hit much harder. This increases the fps and at the same time makes for greater consistency.

[cavninja]

A very good point on lubrication Russ, i always prep mine with a little spray silicone oil, is that the best to use?

[Russe11]

No idea, I use a thicker silicon gun oil. Mainly so I can store it in a WW2 brass oil bottle that fits into the stock for storage