The GBBR Thread

[Samurai]

Probably just the hopup is not turned on at all.

 

[TheGrover]

Probably just the hopup is not turned on at all.

The stock hop rubber held the BB even when it was turned off, and my P228 always lets the BB out, so i always guessed it was just how the G5 was. ill have top see if it lets the BB out when i get it set at my next skirmish

 

[straffham]

Sooooo. . . your gun is bang on the 350 limit on an average day, but you find its running hot on a warm day.

Out of curiosity has anyone tried a mix of green gas and 144a? Say 5 seconds squirt of each gas into a mag (or whatever)? What were the results?

 

[PT247]

Try Abby Predator Ultra if gg is too hot rather than 144a

 

[straffham]

Try Abby Predator Ultra if gg is too hot rather than 144a

Cheers, will look some out, I assumed that was just green gas under a different name tbh. I've tried their brut sniper gas which gives about the same ball park velocity as propane.

 

[PT247]

It is in-between 144a and gg

 

[straffham]

Sounds just the job for those hot summer days then!

 

[Airsoft-Ed]

mine is running HPA which may make a difference?

Nope, sound won't change between the gasses. Noise all comes from the parts slapping each other, has nothing to with gas.

On the topic of muzzle devices though, a mate of mine put a suppressor on his G5 and then unscrewed the cap on the front of it, so it looked like a massively long amplifier, and the gun made the most hilarious "POP" noise you've ever heard lol. Y'know Donkey in Shrek 2 when they're in the little horse drawn cart thing at the start and he gets bored? Well, that exact noise lol.

I got my WE SCAR a couple of weeks back and only got the change to give it a quick blast yesterday, but I had a horrendous time trying to load BB's in all three of my mags, all brand new. I ended up having to load BB's one at a time. Then once I had them loaded they wouldn't feed. Couldn't fire a single BB. The gun fires, no gas issues, it just seems the lips are too hard to allow the BB's to feed. Can anyone give me tips on how to load and what I should be doing to allow the BB's to feed. I've seen in a few other posts above that it is an issue with these guns, and I've looked on youtube for some help, but so far I'm out of ideas.

I'm a little late to the party with this... But I think your nozzle might be broken.

You say it's cycling fine with the gas but there's no shots coming out, and it's new... That to me says that the little pokey bit on the nozzle that loads shots has been snapped off. As the bolt comes forward a round HAS to be picked up, or the bolt would jam when it hit the shots.

Unless of course the bit that loads the shots has snapped off. I'd get some photos sorted but I'm not at home atm. Inspect your nozzle. Under the bit that goes in the barrel there ought to be a little nub that pushes the BBs in. They can break ridiculously easily on the SCARs, both mine and a mate's both broke on our first ever skirmishes with them.

 

[cavninja]

On the topic of muzzle devices though, a mate of mine put a suppressor on his G5 and then unscrewed the cap on the front of it, so it looked like a massively long amplifier, and the gun made the most hilarious "POP" noise you've ever heard lol. Y'know Donkey in Shrek 2 when they're in the little horse drawn cart thing at the start and he gets bored? Well, that exact noise lol.

Are we there yet??!! lol

 

[PT247]

Nope, sound won't change between the gasses. Noise all comes from the parts slapping each other, has nothing to with gas.

It would make a difference if I was consistently hitting higher fps than the gas powered one which this time of year is more likely as the gas is less efficient causing it to expand slower thus putting less power into each shot so the bolt hits softer.

 

[Super64]

Thanks for the info guys, I've been away the past week so not been able to get on the forum to check the replies. I'll get the gun out at some point and check the nozzle and internals to see if anything looks broken, cheers Ed. If it is broke, is that an easy fix?

 

[TheGrover]

alrighty, tested my G5 at the range today and the new hop rubber and nub did the trick, working perfectly as designed.

I also took the opportunity to chronograph the gun on the same gas using different ammo, for my own personal experiment. results as follows:

0.25g BBs: 272fps (83m/s) @ 0.8611 joules (KE) and 0.02075 kgm/s (Momentum)
0.20g BBs: 292 fps (89m/s) @ 0.7921 joules (KE) and 0.01780 kgm/s (Momentum)


What this quick test shows, is that changing the ammo also changes both the kinetic energy and the momentum given to the ammo, and each by different amounts. increasing the mass of the ammo to 0.25g increases the energy of the ammo by about 8.7% and its momentum by 16.6% (double due to the fact that the Kinetic Energy of an object is the product of the velocity squared, and momentum is not)

My theory explaining this is that since a heavier BB accelerates slower (resulting in the lower velocity) it spends more time in the barrel with pressure behind it; thus applying a greater impulse to the BB (since the force supplied by the pressure is independent of the speed of the BB or its acceleration)

TL;DR (or the simpler conclusion) : using heaver ammo actually increases the power of the gun, so take that into consideration when measuring your FPS using anything other than a 0.20g BB

 

[Airsoft-Ed]

It would make a difference if I was consistently hitting higher fps than the gas powered one which this time of year is more likely as the gas is less efficient causing it to expand slower thus putting less power into each shot so the bolt hits softer.

That's true, but you still wouldn't be able to hear it and say, "Ah, that's definitely running off HPA" without looking at it, could be using a higher pressure gas, using a more efficient gun etc.

Thanks for the info guys, I've been away the past week so not been able to get on the forum to check the replies. I'll get the gun out at some point and check the nozzle and internals to see if anything looks broken, cheers Ed. If it is broke, is that an easy fix?

Yeah it's pretty straight forward, you'd have to replace it for a new nozzle, which would involved stripping the bolt, removing the nozzle's guts (don't worry, there's only a one piece valve and a spring) and putting them in the new nozzle before reassembling everything.

Only really tricky part would be if the new nozzle wasn't a smooth fit in the bolt. Some minor sanding and lubing may be required, but you could cross that bridge when you come to it. You can PM me if you need a hand, I might have some videos that can help you or something.

alrighty, tested my G5 at the range today and the new hop rubber and nub did the trick, working perfectly as designed.

I also took the opportunity to chronograph the gun on the same gas using different ammo, for my own personal experiment. results as follows:

0.25g BBs: 272fps (83m/s) @ 0.8611 joules (KE) and 0.02075 kgm/s (Momentum)
0.20g BBs: 292 fps (89m/s) @ 0.7921 joules (KE) and 0.01780 kgm/s (Momentum)

What this quick test shows, is that changing the ammo also changes both the kinetic energy and the momentum given to the ammo, and each by different amounts. increasing the mass of the ammo to 0.25g increases the energy of the ammo by about 8.7% and its momentum by 16.6% (double due to the fact that the Kinetic Energy of an object is the product of the velocity squared, and momentum is not)

My theory explaining this is that since a heavier BB accelerates slower (resulting in the lower velocity) it spends more time in the barrel with pressure behind it; thus applying a greater impulse to the BB (since the force supplied by the pressure is independent of the speed of the BB or its acceleration)

TL;DR (or the simpler conclusion) : using heaver ammo actually increases the power of the gun, so take that into consideration when measuring your FPS using anything other than a 0.20g BB

That is Joule Creep in effect. Heavier ammo = more power instead of the same amount at a lower velocity.

Due to the amount of gas being supplied massively over-voluming the barrel.

 

[Samurai]

My theory explaining this is that since a heavier BB accelerates slower (resulting in the lower velocity) it spends more time in the barrel with pressure behind it; thus applying a greater impulse to the BB (since the force supplied by the pressure is independent of the speed of the BB or its acceleration)

You are correct. Most ppl say that changing the mass shouldn't change the energy but they forget that the systems sarting point is not at the end of the barrel where we measure. The time spent in the barrel affects the different weighted projectiles differently.

It's way more noticeable with GBBRs but it's the same with AEGs - but on a much smaller scale.

 

[Airsoft-Ed]

I tried explaining this today because the marshal at the chrono was INSISTING I chrono on .20s

It was like trying to get blood out of a stone. I ended up setting it myself and telling him another marshal had seen me.

 

[TheFull9]

It's unfortunate a lot of people actually don't know about energy creep and think they can make their gas gun skirmish safe by putting in heavier ammo to bring down the muzzle velocity. Not realising that muzzle energy is what matters. I'd like to see retailers and manufacturers do more to address the problem in manuals/product descriptions etc because the airsoft community as a whole really needs to be made more aware of the fact that 'FPS' is not the number that matters; sites say '350 with a 0.2' for a reason and that second stipulation is what makes the difference of course. As with so many airsoft myths and chinese whispers, the fact that so many people just quote FPS numbers all the time without really understanding what they're talking about has spread a lot of mis-information amongst the community.

 

[Super64]

Thanks Ed, not sure when I'll get round to looking properly as I'm back at work tomorrow, but if needs be I'll take you up on the offer of more help, thanks very much.

 

[TheGrover]

I tried explaining this today because the marshal at the chrono was INSISTING I chrono on .20s

It was like trying to get blood out of a stone. I ended up setting it myself and telling him another marshal had seen me.

To be fair, its the game site rules, if they want you to stuff a few 0.20s in a mag and test it, its not the end of the world.

Ideally, the gun should be chrono'd on your ammo and the muzzle energy used as a limut (about 1.1j is the accepted standard, 350 on 0.2s)

 

[straffham]

Alpha55 banned 0.3s in GBB pistols (and presumably GBBRs, thoughI need to check) last year for precisely the reasons of joule creep.

 

[PT247]

reference joule creep, if a 0.2g BB is bang on 1.1j and 350 fps (there abouts), with heavier BBs would you eventually find a weight that would give you 350fps or will the fps always drop?