Upping my FPS - M4

[Sp3ctre]

All,

I've got a G&G GR16 Carbine Light and it's currently running 270FPS.

I want to up it to between 320 and a max of 340. What's the cheapest way to do that?

I've been told to just get an M110 spring in it, but what gain should I expect out of the spring alone?

Also - With me having a stock gearbox - will it be able to handle the spring without replacing the rest of the inners? I don't want my gearbox lifetime to be cut very short just for the sake of a bit of power (Bushings are metal)

Thanks

[Sir Stephen]

Re: Upping my FPS - M4

give it a good clean internally, and use PTFE tape on the cylinder head, and polish the cylinder a bit. make sure your barrel is dirt free, and that your hop is also clean.
a good air seal give much more benefits than simply putting a more powerful spring in it.

[Sp3ctre]

Re: Upping my FPS - M4

give it a good clean internally, and use PTFE tape on the cylinder head, and polish the cylinder a bit. make sure your barrel is dirt free, and that your hop is also clean.
a good air seal give much more benefits than simply putting a more powerful spring in it.

So a new o-ring, air nozzle and polycarb piston would be better? What gains should I expect to see?

[Sir Stephen]

Re: Upping my FPS - M4

none of it hast to be new, just clean. your fps would increase due to the fact that less air can escape form the gearbox, and its used properly in your hop/barrel.
each shot will be more consistent, which should translate to accuracy as the fps wont change form each shot, and there isn't any random bits in the barrel to adjust the bb's flight path.

with your existing piston o-ring, place it over the outside of your cylinder, and leave it in warm water for a bit (open flame can be used for faster results but you risk burning the rubber)
make sure your piston head is also clean and clear from old grease and any crap.
remove the o-ring form the cylinder head, and clean it, and the groove it sites in.

when everything is clean, used silicone oil in small amounts to "wet" the rubber parts as you replace them.

wrap 2-3 layers of PTFE around your cylinder head over the oring, and then test the seal by placing your finger over the air nozzle and pushing the piston in. if done correctly, you should have less than an inch or so of movement before it cant be compressed anymore.

[Sp3ctre]

Re: Upping my FPS - M4

none of it hast to be new, just clean. your fps would increase due to the fact that less air can escape form the gearbox, and its used properly in your hop/barrel.
each shot will be more consistent, which should translate to accuracy as the fps wont change form each shot, and there isn't any random bits in the barrel to adjust the bb's flight path.

with your existing piston o-ring, place it over the outside of your cylinder, and leave it in warm water for a bit (open flame can be used for faster results but you risk burning the rubber)
make sure your piston head is also clean and clear from old grease and any crap.
remove the o-ring form the cylinder head, and clean it, and the groove it sites in.

when everything is clean, used silicone oil in small amounts to "wet" the rubber parts as you replace them.

wrap 2-3 layers of PTFE around your cylinder head over the oring, and then test the seal by placing your finger over the air nozzle and pushing the piston in. if done correctly, you should have less than an inch or so of movement before it cant be compressed anymore.

Lovely jubbly! Thanks a lot. I'll give it a go at weekend and see what the result is! I'd rather do that before I go slamming a new spring in!

Thanks for your help!

[Mickydoos]

Re: Upping my FPS - M4

Make sure you're not losing air anywhere outside the gearbox. Some guns have a spring in front of the hop on the barrel to push the hop back against the gearbox. If yours doesn't, try one. It caused mag feeding issues for me but could work for you.

Secondly, tune your hop up.

Here's a good guide to hop tuning: http://www.airsoftsociety.com/forums...-hop-up-33545/

Use as much or as little of it as you need. I skipped the bit with the dremelling of the bucking; i didnt think it was necessary. Nor did I do the thing with the hop arm, mine simply didnt need it. The permatex step might also be OTT.

Also, I not only PTFE taped the bucking but I PTFE taped the barrel to hop once the barrel was installed so that virtually no air could escape.

Finally, a tightbore barrel MAY increase your FPS, but it will improve your grouping anyway so is normally worth doing.

[Figjam]

Re: Upping my FPS - M4

Just to illustrate the value of attention to airseal: I had two guns earlier this week low on power - both around the 260 mark with m100 springs in, so something not right.
The one was easy peasy: four layers of insulating tape on the front of the hop unit - where the feed tube buts up against the upper reciever - took it to 370. So took one layer off and brought it down to 340. This is all about getting the hop unit to push more firmly against the gearbox so as to reduce pressure loss between the nozzle and the hop.
The other I got up to 280 doing this, but it wouldn't go any further, so I taped the inside of the nozzle, which got it to 300, and then the hop bucking onto the inner barrel, which brought it to 340.

[jonny lovegrove]

I must be awesome then ^_^ jkjk
But airseal as iterated above makes a huge difference. My m16 had dropped off to ~260, i figured the spring has died as id stupidly left it compressed for a long time, swapped it for an m100 and cleaned it out, chronoed at 374... Dropped the old spring back in and bang on 328 again...

If that doesnt do it for you,
Warrior l96, meant to do ~500 from factory (v3, restrictor removed)
Chronoed 340. Swapped the hop unit for a PDI airseal unit and it jumped to 560. Thats 200fps that was leaking out :/ and also a nice clipped spring for me now...
I have never PTFE'd an air nozzle and hope not to!

Also, if the spring causes feed issues, put an ORING over the air nozzle between the GB and hop unit.

[Mickydoos]

Re: Upping my FPS - M4

I couldn't see a way to get ptfe tape to stay on an nozzle so I didn't try it

[Skolob]

Re: Upping my FPS - M4

As sad above, PTFE the hop rubber to get a god rubber to chamber seal. I've found in many low fps guns, its blow by in the hop chamber.Its also often a sign of worn hop rubber too. You can ptfe the nozzle at the base but it makes bugger all difference and you would e better switching to an o ringed nozzle or just not bothering.
One of the guys I know uses ptfe paste rather than tape which gives good results and is eaier to assemble. I dont like the floss method as it seems to distort the rubber too much.

Grease the piston head ring too as this is the prime point where the air pressure losses can occur, if that doesnt seal you will never get good pressure.

[Figjam]

Re: Upping my FPS - M4

yeah, the PTFE on the nozzle was fiddly as and I fully expect it to not last long, but if it lasts long enough for the airseal nozzle I've ordered to come,then its done its job.

[Sp3ctre]

Re: Upping my FPS - M4

All,
Thanks for your replies, I really appreciate the help!
My hop up rubber has a little slit in it, so I'm going to replace that today (it's the G&G green one that was standard, will replace with a Guarder improved one). Also - I took the hop unit out, put my finger over the barrel and the mag feed opening, then blew in the GB end... the only leakage was air p*ssing out of the TOP of the hop unit :|, where the arm goes in.

Any ideas?

[Mickydoos]

Re: Upping my FPS - M4

Did you do that with the damaged bucking or no bucking? Cos air would piss out there. That's the hole in the barrel where the hop arm and nub press on the bucking. You can't test your seal without an intact rubber!

[Sp3ctre]

Re: Upping my FPS - M4

Did you do that with the damaged bucking or no bucking? Cos air would piss out there. That's the hole in the barrel where the hop arm and nub press on the bucking. You can't test your seal without an intact rubber!

Realised this after I posted lol! Thanks for the help. It was tested with the damaged bucking, I've just been and bought a new one, so will be trying with that one tomorrow!

[Sp3ctre]

Re: Upping my FPS - M4

On Sunday me and my mate took the M4 apart. The hop bucking was knackered so we replaced that with a Guarder one.
We then took the gearbox apart, noticed thst the spring was compressed a fair bit, so stretched that back out, then went for a compression test on the piston... It didnt hold any air whatsoever, so we put new o rings on both the piston and the head, then tried again, and with much better, more promising results... It held brilliantly!
After regreasing we put the box back together and put a tiny o ring round the air nozzle to seal it tight to the hop unit, then tried her again...

What we noticed was a hell of a difference in the sound produced after each shot. The pop sound had gone that I had before, and it seemed to be a lot faster in delivering the rounds to the target.

We havent had her chrono'd yet, but plan to go this week! I think it'll bust the 310 barrier without a shadow!

Again... Thank you all!!