cavninja Posted January 9, 2015 Share Posted January 9, 2015 Does anyone have any GBB top tips to share? I've found with lubrication that dry cleaning and a light spray of silicon oil is better then over doing it or using grease. And a single layer of electrical tape around a GBB mag, so that it improves the fit in to the mag well, improves the consistency of the seal between the nozzle at the top of the mag and the bottom of the nozzle in the gun, Thanks Youtube!! Link to comment Share on other sites More sharing options...
Supporters sp00n Posted January 9, 2015 Supporters Share Posted January 9, 2015 One thing people who are moving to GBBRs need to be aware of is, unlike with an AEG, changing barrel length will change the power. The longer the gas can expand in the barrel the more power you get - so reduce the barrel size and you'll get a drop in FPS. Increasing mine by 4" (using the GHK G5 carbine kit) increased my fps by ~25-30 with 0.20g pellets. There is a limit to the increase - if the barrel is long enough for the released gas to completely expand then the pellet will reach maximum velocity before exiting the barrel - not sure how long ti would need to be though, I suspect far too long to be usable. it is exactly the same with AEG's, as in AEG's as its a compressed air charge vrs barrel length vrs barrel diameter etc. increasing barrel length = more fps, reducing barrel length = less fps etc etc fitting a TBB = increased fps .... you get the picture ill admit i was/am majorly put off buy the cost of gas ... and i was/am a major advocate of AEG/AEP's ....... but i am looking at a WE MP5A3 Link to comment Share on other sites More sharing options...
Supporters M_P Posted January 9, 2015 Supporters Share Posted January 9, 2015 ill admit i was/am majorly put off buy the cost of gas ... and i was/am a major advocate of AEG/AEP's ....... but i am looking at a WE MP5A3 It's not that much more when you factor in that you're firing a few hundred rounds as opposed to the odd thousand each time. With gbbrs I can make a 3000 rd bottle last about 7+ game days- Most aeg users will struggle to get 3 so the savings work out quite well, especially if you're running propane rather than green or other 'airsoft' gas. Link to comment Share on other sites More sharing options...
Supporters sp00n Posted January 9, 2015 Supporters Share Posted January 9, 2015 i should also note ... i work for a company that manufactures aerosols .... (if anyone could email me a COSHH sheet for current gas that would be epic) Link to comment Share on other sites More sharing options...
Josh95 Posted January 9, 2015 Share Posted January 9, 2015 As far as AKs go - GHK is the only choice really, the standard WE offering isn't upto much OOTB and requires upgrading. For roughly the same price a GHK will run beautifully out of the box. Best gun I ever bought tempted to buy a gas gun in the summer, might look into a GHK Link to comment Share on other sites More sharing options...
Supporters Airsoft-Ed Posted January 9, 2015 Author Supporters Share Posted January 9, 2015 it is exactly the same with AEG's, as in AEG's as its a compressed air charge vrs barrel length vrs barrel diameter etc. increasing barrel length = more fps, reducing barrel length = less fps etc etc fitting a TBB = increased fps .... you get the picture ill admit i was/am majorly put off buy the cost of gas ... and i was/am a major advocate of AEG/AEP's ....... but i am looking at a WE MP5A3 As Marcus said, I use hella expensive ammo, costs me £12 a bag for only 2000, but it lasts me about 3 game days, so £4 per game day on ammo, and about £7 on gas based on a £9 propane canister lasting me a little over one game day = about £11 per game day on gas and ammo. That's only slightly worse than an AEG user buying a single pot of 3000 .25s per game day for £10. Most people will buy cheaper ammo than me so their running costs will probably be directly in line with most AEG users. Also, going back to the whole, barrel length alters fps thing, it's actually pretty dangerous with gas guns in some cases because of Joule creep. My L85 shipped with a 509mm long, 6.01mm tight bore and it was almost impossible to chrono safe using my ammo of choice - .28s. I initially chrono'd using .20s to set the NPAS for 350fps, which was the site limit. Conversion charts state that firing .28s through a rifle shooting .20s at 350 ought to lower the power to around 295, but when I re-chrono'd with .28s, it was doing 335... 40fps over the limit for that weight. So adding heavier ammo actually increased the joule output by the equivalent of 40fps... It happens because gas guns fire significantly more gas down the barrel than needed for each shot, the mechanism sends gas forwards until the pressure closes a valve, then that valve redirects the rest of it to the back, which knocks the bolt over the hammer, knocking the hammer off the valve on the mag, which shuts off the gas supply. Lighter ammo doesn't take as much energy to send out of the barrel, .20s probably use up around 20% of the total gas volume being sent down the barrel. So when you add heavier ammo, it takes more energy to push them out of the gun, but gas guns have that extra energy in spades! So the power just increases instead of staying the same with most AEGs. In AEGs it doesn't happen as much because generally cylinders are ported so that the air volume of the cylinder matches that of the barrel, so it takes all the air the gun can muster just to fire a .2 out, so when you add heavier weights, the power remains the same because there's more barrel than air, the shot stops accelerating before it leaves the gun, whereas in gas guns the shot is still accelerating until it's free of the barrel. It's a pretty hard thing to explain... So I hope that explanation makes sense... Basically though, it means that if you don't chrono on the weight you intend to use, you will more than likely be firing hot once you load heavier ammo if you're using a gas gun. Link to comment Share on other sites More sharing options...
cavninja Posted January 9, 2015 Share Posted January 9, 2015 It's a pretty hard thing to explain... So I hope that explanation makes sense... Basically though, it means that if you don't chrono on the weight you intend to use, you will more than likely be firing hot once you load heavier ammo if you're using a gas gun. I think that's a pretty good explanation Ed, cheers, I'm still baffled why sites insist on chrono-ing on 0.2s, surely it would make sense to chrono on what you intend to use and adjust the chrono for the weigh of the BB? I know what you mean about running hot, my 416 was over 400 out of the box, the NPAS is a must! There's also a great vid on Youtube of some Japanese guy doing a power point on how an NPAS works, that makes using it a lot clearer!! lol Link to comment Share on other sites More sharing options...
Supporters Airsoft-Ed Posted January 9, 2015 Author Supporters Share Posted January 9, 2015 I think that's a pretty good explanation Ed, cheers, I'm still baffled why sites insist on chrono-ing on 0.2s, surely it would make sense to chrono on what you intend to use and adjust the chrono for the weigh of the BB? I know what you mean about running hot, my 416 was over 400 out of the box, the NPAS is a must! There's also a great vid on Youtube of some Japanese guy doing a power point on how an NPAS works, that makes using it a lot clearer!! lol It's just a valve with a screw through it so you can alter the overall length. The valves can move forwards and backwards and are sat under spring tension. When gas flows through it the pressure naturally closes the valve against the force of the spring, compressing it, then once the valve is closed it redirects the gas to the rear, cycling the action. The longer the valve, the less it has to move to block off flow down the barrel, so the faster it travels the distance, so the less time gas has to squeeze through the opening, so the lower the fps. If you shorten it then it takes the valve longer to move into position to block off the flow, so the fps is higher. The time it takes to move into position and block off flow to the barrel is referred to as "dwell" time, and once the action cycling cuts off the gas supply, the pressure drops allowing the spring to return the valve to its original position. It's kinda weird to think that you have the main bolt, which moves back and forth, then inside that is the nozzle, which moves back and forth, and then inside that you have the valve which also moves back and forth and one moving sets off the next, so it's like a Mexican wave effect. Valve moves forwards, which sets off the nozzle moving forwards relative to the bolt which moves backwards away from it. Then the bolt shuts off the gas flow, returning the valve to its original position, as well as the nozzle via the nozzle return spring, and then the bolt itself via the recoil spring. And it all happens in like, less than half a second. It's seriously awesome lol. I really wish I could make some 3D animations showing how it all works, 'cos I think it'd be amazing to watch happen in slow motion, but obviously the parts can't all be made transparent and I'm shit at 3D modelling... To the point where I wouldn't even know where to start =[ I find it mind bogglingly fascinating in its simplicity though, and it makes me wonder why you can't have an NPAS for all gas weapons, including pistols... I mean, it's just a valve that you alter the length of with a screw... Surely to god that can be produced to allow pistols to alter their fps too? Hell, why not just produce myriad valves of different lengths for the fps required? Smaller = more fps. They could label with with the fps they produce so you could get like "Sniper valves" or "CQB valves" or whatever. I'm amazed manufacturers aren't trying to milk us dry by doing it that way instead of providing us with one thing that can be adjusted by the user. It's like capitalism was asleep and missed an opportunity lol. Link to comment Share on other sites More sharing options...
cavninja Posted January 9, 2015 Share Posted January 9, 2015 It is complicated and simple all at the same time?! lol, that's why I found this guys explanation a real help in getting my head round what I was trying to do with my NPAS!! I'm sure i once saw something that was billed as an FPS reducer, kind of like a set of spacers that fitted on or behind a muzzle flash, they were colour coded for differing amounts of reduction? Or maybe i'm getting confused with something for AEGs? Link to comment Share on other sites More sharing options...
Supporters sp00n Posted January 9, 2015 Supporters Share Posted January 9, 2015 your welcome bo11o..s was beaten to it Link to comment Share on other sites More sharing options...
Supporters sp00n Posted January 9, 2015 Supporters Share Posted January 9, 2015 As Marcus said, I use hella expensive ammo, costs me £12 a bag for only 2000, but it lasts me about 3 game days, so £4 per game day on ammo, and about £7 on gas based on a £9 propane canister lasting me a little over one game day = about £11 per game day on gas and ammo. That's only slightly worse than an AEG user buying a single pot of 3000 .25s per game day for £10. Most people will buy cheaper ammo than me so their running costs will probably be directly in line with most AEG users. Also, going back to the whole, barrel length alters fps thing, it's actually pretty dangerous with gas guns in some cases because of Joule creep. My L85 shipped with a 509mm long, 6.01mm tight bore and it was almost impossible to chrono safe using my ammo of choice - .28s. I initially chrono'd using .20s to set the NPAS for 350fps, which was the site limit. Conversion charts state that firing .28s through a rifle shooting .20s at 350 ought to lower the power to around 295, but when I re-chrono'd with .28s, it was doing 335... 40fps over the limit for that weight. So adding heavier ammo actually increased the joule output by the equivalent of 40fps... It happens because gas guns fire significantly more gas down the barrel than needed for each shot, the mechanism sends gas forwards until the pressure closes a valve, then that valve redirects the rest of it to the back, which knocks the bolt over the hammer, knocking the hammer off the valve on the mag, which shuts off the gas supply. Lighter ammo doesn't take as much energy to send out of the barrel, .20s probably use up around 20% of the total gas volume being sent down the barrel. So when you add heavier ammo, it takes more energy to push them out of the gun, but gas guns have that extra energy in spades! So the power just increases instead of staying the same with most AEGs. In AEGs it doesn't happen as much because generally cylinders are ported so that the air volume of the cylinder matches that of the barrel, so it takes all the air the gun can muster just to fire a .2 out, so when you add heavier weights, the power remains the same because there's more barrel than air, the shot stops accelerating before it leaves the gun, whereas in gas guns the shot is still accelerating until it's free of the barrel. It's a pretty hard thing to explain... So I hope that explanation makes sense... Basically though, it means that if you don't chrono on the weight you intend to use, you will more than likely be firing hot once you load heavier ammo if you're using a gas gun. to be honest i think there has only been 2 or 3 times when i have used more than 1K bb's (my local site is semi only so usually a hicap very very easily lasts a game or 3 ... i should use my 120rd mid caps ... i am just lazy barrel length and joule creep are different issues, that said one can effect another ... if that makes sense i feel your pain ed, one day my G&G L85 was fine with 0.25's (310fps) the next week i was shooting at 328 -335fps ... the only thing i had changed was the flash hider to a surefire clone ... i cannot explane that (it should be noted that i have had a lot of issues with the FPS on my L85 ... originally it would only shoot at 404fps no matter what spring i fitted ) Link to comment Share on other sites More sharing options...
Supporters Airsoft-Ed Posted January 9, 2015 Author Supporters Share Posted January 9, 2015 barrel length and joule creep are different issues, that said one can effect another ... if that makes sense They are different, but the longer the barrel, the more power a gas gun can put behind even a low weight shot. So the danger associated with joule creep gets amplified by longer barrels. Longer the barrel, the more gas can be applied to the shot. Once I get a chrono I'm going to do some proper tests and record it, 'cos I'm really interested to see how powerful I can make my L85 if I really ramp it all up - long tight barrel, heaviest ammo I can buy, NPAS cranked all the way open. I reckon it'll make short work of pretty tough shit, thinking of testing it against tins of beans. But anyway, I ended up fitting my L85 with a shorter barrel, now there's about 6 inches of outer barrel over the end of the inner barrel, just because I didn't want to risk any freak heat waves from turning my L85 into a hole punch lol Link to comment Share on other sites More sharing options...
Guest PT247 Posted January 9, 2015 Share Posted January 9, 2015 If after GHK guns then Samoon are well worth checking out. Fantastc service, free bits and they understand our customs/VAT rules. Fast shipping too and probs cheapest G5 mags you'll find if buying in pairs! Link to comment Share on other sites More sharing options...
Chock Posted January 9, 2015 Share Posted January 9, 2015 Does anyone have any GBB top tips to share? I've found with lubrication that dry cleaning and a light spray of silicon oil is better then over doing it or using grease. Just to be clear here, unless you are unbelievably careful about where any oil or grease is going, silicone oil is really the only stuff you should be using to lubricate your gas blowback (or even non blowback) weapons, because other types of oil or grease can attack the rubber and synthetic o-ring valve seals on your mags and weapon internals. So don't be spraying WD-40 or some stuff like that in your GBB, or you may wreck the thing and have to take it apart to replace the seals on it. You don't need to go to an airsoft store to find silicone lubricant incidentally, you can find aerosol silicone lubricant in most car spares places, and it will cost you maybe a fiver for a can of it, which usually comes with a little straw attached to the can so you can direct the spray onto the working parts properly. Theoretically if you were careful, you could use other lubricants on parts that don't have any rubber or synthetic o-ring gas seals, but if you stick with the silicone lubricant, you can cheerfully spray it all over the internals of the weapon and not worry about it at all. Another thing to watch out for when it comes to lubricating your GBB (or rather prior to doing so), is to be especially careful if it is an AK74 or AK47 with wooden furniture. In emulating a real AK, the wooden furniture on a lot of airsoft AKs, is not always brilliantly finished, so in fact it is not always properly sealed with varnish. This means that if you start spraying lubricating oil about, and it gets onto unsealed wood, not only will it weaken, distort and swell the wood as it soaks in, but it will also stain it. So, one of the best things you can do with a new GBB AK, is to check the wooden furniture to see if it is sealed with varnish (paying particular attention to the unseen parts of a wooden fore grip, and especially any end grain bits). If it aint thoroughly covered with varnish, give it a quick spray or brush over with some to ensure that it is, and in fact, the crappier a job you make of doing that that, the more authentic it will actually look, given the fact that the average real AK's wooden furniture looks like it was painted by a blind man who was having an epileptic fit at the time, and the average Chinese Type 56 looks like it was painted by that blind man's pet dog. Link to comment Share on other sites More sharing options...
cavninja Posted January 9, 2015 Share Posted January 9, 2015 If after GHK guns then Samoon are well worth checking out. Fantastc service, free bits and they understand our customs/VAT rules. Fast shipping too and probs cheapest G5 mags you'll find if buying in pairs! Awesome tip! I've now got a serious fire in my pocket!! Have you ever imported from them? any experience on what its like with import tax/duty etc? I've just compared the prices of a GHK M4 + 5 mags and you can save yourself about £200! but it's no good if the tax man shafts you once it gets here! Link to comment Share on other sites More sharing options...
TheGrover Posted January 9, 2015 Share Posted January 9, 2015 This thread is turning me to the dark side. I think i might be buying a GHK G5 when my bank account catches up Link to comment Share on other sites More sharing options...
Guest PT247 Posted January 9, 2015 Share Posted January 9, 2015 I have gotten all my G5 bits from them gun included... and 10 extra mags!I ordered in several stages: 1st order G5 2nd 6x mags 3rd 4x mags They all came through very quickly. I had to pay the Parcel Farce fee of £13 on each order and custom charges. I did not have to pay VAT and they threw in a funky G5 T-shirt, an upgraded spare piston seal set and some GHK silicone oil (which is reportedly the best silicone oil you can get for GBBRs. Obviously I had to pay postage on each order but had I done the whole lot in one hit I imagine I'd have had to pay VAT too so swings and roundabouts. At the time, compared to my closest GHK shop in UK the gun and 4 extra mags + fees cost roughly the same as just the gun in UK. The cost of the G5 has come down a bit over here now so the gap is getting smaller, but still money to be saved.... especially when mags are £45 in the UK so £90 for 2 plus P&P, when you can get 2 from Samoon for £45 + P&P&customs Link to comment Share on other sites More sharing options...
TheGrover Posted January 9, 2015 Share Posted January 9, 2015 Can you reccomend the G5 as a first GBBR? I think i can feel the dark side calling Link to comment Share on other sites More sharing options...
cavninja Posted January 9, 2015 Share Posted January 9, 2015 Cheers PT, great stuff, it would seem the fire in my pocket is saying "GHK M4! You know you wanna!" Come to the dark side Grover! We have recoil!!! Link to comment Share on other sites More sharing options...
Guest PT247 Posted January 9, 2015 Share Posted January 9, 2015 The G5 is my first GBBR and so far is the only GBBR I'll ever really need. I run mine on HPA with a home made hi-cap now rather than gas which means no cool down and even more consistency between shots fired. The G5 gun and mags are really good all year round and although you'll notice a drop in FPS in winter they will still fire every round straight and true (just not quite so far as in summer). I play in woodland and range has never been an issue with the gun. Dead simple to strip for cleaning. It is a bit fiddly to change barrels/hop rubbers etc but not difficult, just harder than on an M4 AEG. Not sure how the GHK M4/AK strips down, they may be simpler than the G5 for gaining access to hop and barrel.Only bad thing about the gen 2 G5 is the hop adjuster location IMO. Link to comment Share on other sites More sharing options...
TheGrover Posted January 9, 2015 Share Posted January 9, 2015 Cheers PT, great stuff, it would seem the fire in my pocket is saying "GHK M4! You know you wanna!" Come to the dark side Grover! We have recoil!!! I want to. Ive already sold my soul to the gbb devil but my wallet is still putting up a fight Link to comment Share on other sites More sharing options...
Mr Monkey Nuts Posted January 9, 2015 Share Posted January 9, 2015 Silicon oil is a very poor metal on metal lubricant, by all means use it to lubricate any o,rings or rubberized components, but for metal on metal contact in a GBB I like to use a much higher viscosity lube. I have been using Abbey Silicon Grease recently and in the past have used mechanics lithium grease to good effect. Link to comment Share on other sites More sharing options...
cavninja Posted January 9, 2015 Share Posted January 9, 2015 Silicon oil is a very poor metal on metal lubricant, by all means use it to lubricate any o,rings or rubberized components, but for metal on metal contact in a GBB I like to use a much higher viscosity lube. I have been using Abbey Silicon Grease recently and in the past have used mechanics lithium grease to good effect. I tried various different types of silicon grease and graphite grease and still find spray silicon oil the most efficient and best to use. Easiest to clean, easiest to reapply and offers the best performance, particularly in cold weather. I've not tried any of the grease in the summer months, it'll be interesting to see how it gets on. Link to comment Share on other sites More sharing options...
TheGrover Posted January 9, 2015 Share Posted January 9, 2015 Back to Ed's OP, how do you control the FPS of a GBBR? In an aeg we just swap a spring, but say i wanted a g5 carbine and also wanted to keep it at ~330 fps, can i fit a different nozzle to adjust the FPS to suit site requirements? Thanks Link to comment Share on other sites More sharing options...
Guest PT247 Posted January 9, 2015 Share Posted January 9, 2015 yup, you can fit an NPAS (think that is what they are called. Stronger/weaker gas can help too. Or go HPA and can then set it to what the hell you like! Link to comment Share on other sites More sharing options...
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