I'm having a go at building a Maxim. I dont have the engineering skills of some here nor do I know much about airsoft gun internals but I'm not going to let that put me off. I'm building the body in wood and plastic and getting a mate to weld up a frame and the shield for me.
I've started with the barrel shroud which I cut out of some spare drain pipe I had out of a skip. I cut holes and then strips of pipe between the holes. I then cut a second bit of pipe slightly shorter and cut a strip out of that so that it fits inside the first piece. I then sanded a chamfer along the edges and finally piped in a bit of painters caulk to help smooth it out. Hopefully when it's all painted it will look (at a distance) like a fluted barrel jacket.
I brought a small sheet of exterior ply to make the receiver box. Once again when it's all painted up it should look ok.
For the internals I've sacrificed my p90 and I've ordered a plug and play mosfet which should enable me to slow the rate of fire down nicely. I'll probably get some p90 midcaps which I believe hold 190 rounds so that although the support gunner will have a good ammo allowance he will still have to change mags to give some sense of realism. I have a spare inner barrel from an old upgrade on another gun so that will go on the hop unit instead of the stubby barrel that it currently has, and as it's set for CQB the fps is only around 320, I might get a stronger spring fitted to give it some power but not looking to go mad.
I've just ordered some file handles from ebay to fit on the rear and have been reading through all the other Maxim / Vickers threads on here to get ideas on how to put it all together.
That's come out really well, it's always a bugger trying to replicate pressed steel fluting. Look forward to seeing the rest of it!
As regards the fps, you may find with a longer barrel, you might not need to up it at all.
i second all dieselmonkey said,finish the gun then do upgrades when you know what you have.probably for a p90 box the best thing is to change the cylinder for a non ported one to match the longer barrel,should increase power but put no extea strain on the workings.i like your solution to the barrel jacket and may copy it as it look good,keep it up ,from what ive seen and learned you can get verry good results without being over technical in design and its time that gets results more than skill. 
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
Very nice 
Who needs machinery eh, basic tools and scrap materials are more fun when building your gun, you get more of a sense of achievment when the finished product comes out looking how you wanted it to, keep it up Jimbo, its looking good.
Looking really good there! I was considering a very similar replication of the fluted water jacket for my second Vickers build (my first has the later style smooth water jacket)
A Proud Member Of 'Team Spleen!' who play mainly at Gunman Airsoft, Tuddenham, Suffolk.
Great stuff
Just a couple of pics of progress, every time I go near the project the wife wants grass cutting, or this and that doing but I got a bit more done this evening. You can clearly see that I'm keeping the p90 reasonably intact and building the rear box section around it. The muzzle of the p90 fits into a bit of 15mm pipe that runs all the way through that front end, the inner barrel will fit in there and be held in place with some kind of barrel spacer.
have you got a barrel for it yet,just looking at you'r picture you may want to measure how long a barrel you need,for my bren i had to use a psg1 barrel as that was the longest i could find,my only worry was that retaining the front of the p90 may make it too long to find a barrel ,haveing said al that it wouldent matter if the inner barrel doesent go all the way up to the muzzle.
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
,haveing said al that it wouldent matter if the inner barrel doesent go all the way up to the muzzle.
very true, my MG42 has a standard length AK47 barrel in it which ends about 6" from the muzzle. Works perfectly! Super long barrels are really unnessersary IMO especially in a machine gun where you actually want a good spread of rounds for suppression.
“I wanted to come to the Volga at a specific location at a specific city. By chance it carries the name of Stalin himself. So don’t think I marched there for this reason – it could carry another name – but because there is a very important goal... this goal I wanted to take – and you know – we are very modest, we have it already."
Adolf Hitler, November 1942
"Comrades, Red Army men, commanders and political workers, men and women guerrillas! It is on your perseverance, staunchness, fighting skill and readiness to discharge your duty to the country that the defeat of the German-fascist army and the liberation of the Soviet land from the Hitlerite invaders depend! We can and must clear the Soviet land of Hitlerite vermin."
Joseph Stalin, November 1942
I've also got hold of a plug and play Mosfet thingy so I should be able to slow down the rate of fire. (when I work out how to use it 
)
Quality Jimbo. You are the salvager!
I'm a hero with coward's legs.
Taking shape! Are you going to have it on solokov's mount and the sheild?
I'm hoping to mount it on something that looks like solokovs mount with a metal plate, it will depend on what I can find as a suitable donor.
I'm hoping to mount it on something that looks like solokovs mount with a metal plate, it will depend on what I can find as a suitable donor.
Renault Scenic 
or Mk1 Transit 
I'm a hero with coward's legs.
There is a de-ac at Ford Ranges, complete with mount and plate, but Terry wont let me nick it.
He's a cruel man
I'm a hero with coward's legs.
All the motor assembly has been dropped off to my tech guy to have the original trigger mech removed and changed for a simple push button switch. Whilst it's there he's going to fit the mosfet and see if we can wind the rate of fire down to the magical 500 rpm.
BTW if anyone has any p90 midcaps that they have no use for and want to flog off cheap then please let me know, I've only got two at the moment so the Maxim gunner's No2 crewmember is going to be busy with the speed loader unless I get some in time for Sevastopol!