Why not make it Electric blow back?
Not much moves externally, the barrel recoils, thats about it.
aka Stigroadie
AFRA
better by design
"Truth is a shining goddess, always veiled, always distant, never wholly approachable, but worthy of all the devotion of which the human spirit is capable. "
heres a video of the M2 up at our site, the lads built it themselves 
theres one hell of kick on it as well 
uses a compressed air divers bottle and regulator to power it
http://www.youtube.com/watch?v=OT2l2rZO ... jVKtcEMF_M
The build site associated with the M2 in that video appears offline.
The link I have is http://www.stealthstudios.co.uk/catman/50cal/m2.html
yeah, noticed that myself, I need to pm Hugo (catman) on our airsoft site to see what happened 
at least a good few of the vids are still on youtube
will keep you up to date 
M14 or P90 boxes will be the easiest to get.
As for rate of fire: don't you want a realistic rate of fire then?
i'd have to agree that a support weapon doesent lend itself to gbb firstly because of the cooldown effect caused by sustained fire would be a problem that would probably require a heater element for the gas resovoire even if an external tank was fitted,secondly most gas magazines are of relativley low capacitys and again no sustained fire possible.an electric blowback is a far more practicle proposition and a number of ebb gearboxes are now on the market and the only mod would be to replace the fake bolt with a light weight fake browning bolt.
is this your first build project? if so it might be wise to build the gun first and get it to work well before adding to the complexity of a blowback system,its easy to assume that building it will be easy but the truth is to get a good result i.e a good performance requires a high degree of presition .
i've often been asked by younger airsofters "is it blowback"when looking ak one of my custom guns and they loose interest when i say no but the truth is that for a one off project its an achievement to get them to work well at all espetially for a first attempt.i'm not trying to put you off but its best to be fully aware of what you are doing before you start.
if you do go ahead prease put up a build thread on the forum as we a love to see each others work and if you go for the gas option i'd recomend useing as mutch of the donor gun as poss as in a 50 cal it can be hidden inside,there are quite a few clone gbb m4's out there that might be worth looking at but you would be slaved to lo-cap mags,if you had enough mags it might be a useable support weapon.
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
I'm not desperate for the realism side if I'm honest - This purchase is more for the look and feel of having a Browning .50cal not for how realistic I can make it (almost blasphemy I know) ...Its more part of a rogue, post apocalyptic unorganised rebel clan who have grabbed what they can find !
Obviously I'm not looking for a squillion rounds a second but something that sounds formidable at the business end and can lay down some speedy suppressive fire.
My TM P90 runs 1030 rounds per minute, so my original gearbox recommendation stands.
I'm not desperate for the realism side if I'm honest - This purchase is more for the look and feel of having a Browning .50cal not for how realistic I can make it (almost blasphemy I know) ...Its more part of a rogue, post apocalyptic unorganised rebel clan who have grabbed what they can find !
Obviously I'm not looking for a squillion rounds a second but something that sounds formidable at the business end and can lay down some speedy suppressive fire.
My TM P90 runs 1030 rounds per minute, so my original gearbox recommendation stands.
p90 gearboxes are great,easy to work on and strong ,kh mountain have them in stock
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
The M4 gearbox needs a grip to hold the motor.
The M14 and P90 gearboxes have a cage to hold the motor, and are closer to parallel to the barrel.
I will have to put my neck on the line and say a version 8 gearbox, which is the m249 gear box. It uses many m4 parts and has a quick change spring system. So you can change the spring and spring guide without opening the gear box. It comes with 2 easily accessible screws which you can attach to the inside of the 50. Comes also with a switch which is not part of,the gearbox so u can place it were ever u want. The version 6 or p90 gearbox already has a mod to use for the blowback.
Yeah. a 249 box would be good too, but I've not seen any in stock anywhere.
As for the switch: on both P90 and M14 boxes, the switches are external too.
"Blowback" on an M2:
1) The bolt runs back and forth in a track on either side - The visible moving part is the round bolt head in the track - the handle doesn't move with blowback.
2) The barrel retracts into the jacket for every shot.
I'd always thought that if I made any browning MG, I'd use external solenoids, etc. to drive blowback.
Yeah. a 249 box would be good too, but I've not seen any in stock anywhere...
eHobby Asia have them in, $90 plus post:
http://shop.ehobbyasia.com/upgrade-part ... s-aeg.html
"I was fabulous, and it was a bloody good laugh."
I think i've decided not to go ahead with GBB or EBB at this time as I really don't think I'm techy savvy enough to attempt it and may break a large investment !
As for the Gear box I see its been narrowed down to the M249 or the P90, I think now I need to know which is of a higher quality if any ? Would there be any noticeable difference between them eg. ROF ? (Has anyone had any experience with the S&S M2 ?
As I'm going to be able to fit a large battery in the 'shell' I have been looking around and some big batteries but I would be interested to know if any of you have actually got a Browning M2 and what do you run it off ?
Ollie
249 Gear boxes are generaly desgined for sustained fire whereas the smg/Assault rifle ones arent i seem to remeber, so it might be better going with a 249 one
WW2 Weapons AGM Sten, AGM MP40
m249 boxes are rare as hens teeth if it breaks and at least twice the price,my bren uses a version 6 box and 30-40,000 rounds of sustained fire has had no ill affect on it.
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
small connector and most version 2 stuff fits exept the tappet plate and they are easy to come by.battery wise if its rof you'r after a nice 11.1v 20-25c lipo is what you want largest mahr the better but wise to fit a mosfet as well.the best place for lipo's is "the component shop" as for mosfets £30 quid will get a reliable one.
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
I haven't any experience of the P90 gearbox, even though I've heard good things about it, but I do have an A&K Minimi, and the gearbox is like a brick out-house, largely V2 compatible, and has a quick change spring.
The same box went into the M60 variants, because they saw no need to upgrade it.
If I was building a support weapon it's what I'd use.
"I was fabulous, and it was a bloody good laugh."
Yeah. a 249 box would be good too, but I've not seen any in stock anywhere...
eHobby Asia have them in, $90 plus post:
Or P90 for half the price:
http://www.khmountain.com/airsoft/produ ... ts_id=1383
Don't forget, the M2, and even the 1919, has tons of room inside, so there's no need waste money on a 249 box - save that luxury for an MG34 or MG42.
And remember: Warren uses P90 boxes in the Brens he makes.
As for connectors: You're going to be rewiring it anyway, so use a MOSFET unit with Deans connectors - That's 2 of the effective methods of increasing rate of fire over stock setups.
The p90 hop is also where you should look if you're wanting top-feed.
...Or P90 for half the price:
http://www.khmountain.com/airsoft/produ ... _id=1383...
Last few orders from KHM haven't been reliable, either missing items or "out of stock" notifications...
...they're cheap for a reason...
...tbh I've now given up on them totally, and I stick to EBB, RSOV or eHobbyAsia.
"I was fabulous, and it was a bloody good laugh."
pretty mutch the same setup as in my bren ,just ask anybody who's been on the wrong end of it about formidable rof 
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
...Or P90 for half the price:
http://www.khmountain.com/airsoft/produ ... _id=1383...Last few orders from KHM haven't been reliable, either missing items or "out of stock" notifications...
...they're cheap for a reason...
...tbh I've now given up on them totally, and I stick to EBB, RSOV or eHobbyAsia.
So get it elsewhere, then. That was the first I came across.
In fact, you could almost buy a whole P90 for the price of that 249 box, and solve the hop-sourcing issue at the same time - I believe that's what Warren does for his Brens.
The fact remains a P90 box will be cheaper wherever you get it, and will be perfectly suitable.
