DMR Project 90% complete.

[LazyMcCrazy]

LETS KICK OFF!
Started this project 3 months back as sort of a trickle project, when I saw something I wanted for it I’d get it. Until last week all I needed was gearbox internals, now they’ve come I’ve assembled it and want your advice how to get better range, reliability and just general kick-assness.

This is a 500fps project. I know there is not much gain compared to a 450 gearbox but I didn’t want that, I wanted 500. So please do not post about this is pointless ect.

The externals assembled:



A few issues I had: The free float rail "delta ring"(if that's the name for it as its not holding a hand guard?) was pretty poorly made with a huge chamfer on the edge of it that wouldn’t hold correctly onto the outer threaded ring. When I tightened it for the first time I knew after a bit of stress it would strip.
This photo explains better:



So I made a ring that would fit between the both and hold it all together on as much surface area as possible:


So that’s the rail sorted. The next problem was the quick release silencer. The adaptor was too big to fit on my barrel, so I turned down a piece that fits nicely in between and keeps it in place:


That’s about as far as I need to go body wise. I don’t want this to be a magpul'ed blinged up gun that everyone goes ooo, sexy. I want it to be a gun that people look at an go, looks ok. But after we get back in from the game I get compliments on the performance. Id rather spend 300 on internals than externals.

So, to the gearbox.


Internals:
JG reinforced gearbox (yes iv heard the front end gets smashed off these but I have one and it looks beefy enough so with sorbo I’m hoping it won’t.)
Ultimate double o-ring cylinder head (with sorbo)
SHS o-ring nozzle
SHS full metal teeth piston
Shooter ported ali piston head
SHS spring guide
SHS m150 spring
SHS stainless cylinder to suite 509mm barrel
SHS 7mm bushes
SHS 18:1 High strength gears
SHS tappet plate
SHS Super tourqe motor
JG anti reversal latch
JG trigger + block
JG selector plate
16awg rewire
Hard wired Burst Wizard King Kong


Modifications:
Well greased/ lubed as always
Shaved 1 tooth off the sector gear as I didn’t like how far the piston was going back.
Dremmled down the back of the gearbox to suit the spring guide.
Rubbed the tappet plate against some abrasive paper to slim it down as it was a touch too fat for the gearbox.
AOE correction

I plugged this into one of my 7.4v batteries and it pulled it back this much before giving up:



I planned on running this on 14.8v lipo anyways so that shouldn’t be a problem.


Hop wise I have a Lonex hop that came with a fairly hard rubber that I’m going to give a go stock before pulling off any fancy hop mods. Please post on what hop mods you’ve tried and had good results from please


I plan when it’s shooting well to apply a few drops of wax around the top of the outer barrel to hold the inner barrel snug in place.

Please any suggestions on what could be done better/ cause improvements put below as I’m perfectly willing to rip the gearbox open and change stuff about. If I do get a phenomenal air seal and I’m over 500 or touching it ill be going back in there anyways to shave a few more teeth off.

[madwelshman]

Re: DMR Project 90% complete.

i'm a little confused...

Where is the logic in putting in a spring that on less than half the travel of the piston is pushing out 500 fps... the kinetic power that spring must be capable is pointless and the extra strain your putting on pretty budget parts at best is daft...

Use a normal spring pushing 500 with full compression, would work out a hell of a lot less strain!

[LazyMcCrazy]

Re: DMR Project 90% complete.

I was informed that a m150 spring will push 500 at full compression?
150mps = 492.125fps

[laurence]

Re: DMR Project 90% complete.

In terms of gearbox cracking, a good little thing to do would be to file down the corners a little where the cylinder sits at the front of the gearbox so it is more rounded and thus less likely to crack the gearbox.