Version 2 gearbox reinforcement M4/M16 platform

[luke213]

Hey guys I've run into a problem thankfully it's got an easy quick solution but I'm also looking for a long term solution. Well I've been building an M16 DMR type of rifle for a little while now, and doing it on the cheap. So I started with a used unknown version 2 gearbox and since I had little money in it I decided I'd just see how long it would last with an M140 spring before failing. I didn't take any precautions since it was sort of a test. I didn't run sorbo, I didn't radius the front edges of the cylinder opening or anything else. Well after approximately 5,000 shots I cracked the front off the box, repaired it(tried brazing it just to see if it would work), and promptly blew the front end out of it.

So I picked up another basic version 2 shell, this time a JG reinforced. I had considered dropping the cash for a retro arms gearbox but I'm not a huge fan of aluminum on a good day. Paying fairly high dollar for that was making my wallet itch, so I went cheap and decided to look further into reinforcement options. If someone made a decent priced steel box I'd probably spend some cash and make that jump but only if I knew this was something I was going to keep rather than sell. Right now I don't have allot of money in the platform, more time. So if I sell it off I'm not loosing much if anything on the build. As it was before the break on the box the gun was running a consistent 515fps with .2g's, I'll probably drop in an M150 to bring it up closer to my goal of right on or very close to 550fps.

Anyways back on point, I've been looking at options. As I've seen there are STS systems which I wish I knew existed before yesterday but I didn't. That looks interesting but I'm not finding a ton of first hand information on how well they work in practice. I've seen a couple video's including the one from Ajax customs where they blew the front of a box off without it in place. Seems the guys that run them from what I've seen are happy with them but I'm curious if anyone here has any additional first hand info. This seems sort of like the ideal since I do like to play in cold temps, typically through the whole winter down to 10F or so usually. I hadn't planned on even using this gun in winter temps because I didn't expect it would survive but with that additional load distribution I'm curious how it might change that.

A diy mod I've seen but doesn't make allot of sense is using tin or metal tape to cover the end of the box. That tape is crazy good at sticking things together but I have a hard time believing it's got enough strength to really make any difference other than making someone feel better. So curious if other guys have tried this and have any results on heavier hitting builds.

I've seen another guy on youtube basically braze muggyweld which is a low temp brazing rod for pot metal to reinforce and repair a KWA gearbox. That's close to what I tried, though I don't have the low temp stuff only aluminum repair rods, which just got the temps far to close to the failure point of the pot metal. The rods melt around 700F, and the body melts in the same range maybe a little hotter, but too close to do with a torch without melting the body. The 350F stuff looks like it would work but seems like a little of a fiddly solution, as well as changing the heat treat of the body near the brazing and I have no idea if or how pot metal is heat treated.

So of those three the STS seems like the best option to me, but I'd love to hear if anyone has any first hand experiences with either the ajax version or the newer import variants.

Take care!

Luke

[Gimpalong]

I remember their being some chatter about these on Arnie's about 5 years ago when the STS was released. I seem to recall that the group that was using them played in Arizona and had ridiculously highly FPS rules, like 500 FPS for a rifleman was normal. My impression was that they did this to be able to have longer range engagements and not to be total douchers.... anyway, I digress.

One of the main guys I remember talking about them called himself Radrockin on Arnie's. You might try PMing him.

http://arniesairsoft.co.uk/forums/index.php?/topic/156484-shock-transfer-system/

Review on ASC:
http://www.airsoftcanada.com/showthread.php?t=96420

It's been such a long time, I kind of doubt the STS is even still being made. That might be your biggest problem.

[luke213]

I've actually read most everything I could find via google about them in the last 24 hours;) I'm a research junkie but I figured there might be some guys out there using them or had used them that never posted anything about it. I actually posted this on Airsoft Sniper forum as well since those guys or at least some of them build some high FPS DMR type of builds so I figured there was a fair chance someone had used one. And I actually heard back from a guy who is known to be pretty dang knowledgeable that he's used them and had good luck with them. So now I'm leaning that direction, I think I'll be adding one to this build and see how it goes.

As far as production I actually talked to Ajax Customs this morning and they apparently still sell them, but they have been using a new cylinder head that is milled down and a piece of sorbo added. More less it's like a normal sorbo install but by milling it down they are not decreasing cylinder volume as much as you would be with a normal install. As well you shouldn't have as much of an AOE problem. But I also have seen clones of them in several spots but I'm looking at Clandestine Airsoft:

http://www.clandestineairsoft.com/gearboxes-and-stss-c-1_6_35/pps-sts-shock-transfer-system-for-m4-rifles-p-327.html

I've bought a fair number of parts there, fast shipping, great prices and just overall good experience other than a few parts issues. But those were cheap parts could have happened anywhere.

I'd still like to hear if anyone has had any luck with them as well since more information is always better than less;)

Take care!

Luke

[natethegreat]

Well first off, the retro arms gearbox could withstand springs even higher than a prometheus ms210 (strongest spring on the market), the aluminum (7075 t6 billet) is not expensive for no reason. A simple radius and sorbo on most v2 gearbox shells will yield great results. The jg gearbox is fairly strong as some people run m190 55rps dsg's on them with no problems. A steel gearbox would really be unnecessary when the retro arms would be way lighter and stronger. Aluminum is actually used in most racing engine blocks. As for an sts or shock transfer system, you really don't need one if you do proper radius'ing and sorbo'ing. I usually only recommend sts's to people wanting to run a weaker shell with a high stress setup. You should not experience any gearbox shell failures if you do the precautions that i mentioned. If you do, a lonex gearbox which is virtually indestructible is only $50. Hope this helps, happy building.

[luke213]

I figured the Retro Arms would be tough enough what concerns me with aluminum is that it work hardens faster than steel which was my concern with the push against the front of the box. My interest in steel is purely the fact that if it's the right composition it's much tougher than aluminum the only downside would be weight, but we're talking small amounts here overall. Likely about the same weight as the pot metal if I put up a guess. I know aluminum is used in blocks, intakes and all sorts of other applications when it comes to automotive applications but allot of that has to do with weight rather than strength. Or more accurately, strength to weight as a ratio. Hell rims, etc are aluminum but it's allot softer than steel and in the case of rims I've run into times where I've lost lugnuts either because they weren't torqued to spec, and then worn the other holes making the rim useless, on a normal steel rim you can mount up 3 normal lug nuts on a half ton truck and run it without much issue. Or at least I've never seen them loosen nor fatigue on my woods trucks hauling very heavy loads. I don't think there is a truck out here we use for work without at least one sheered stud, or garbage threads either way. But steel is typically much stronger by about 3 fold from the reading I've done. Much harder to mill and work with, but in gearboxes we're space limited, but not really weight limited, so I'd love to see a transition to steel for parts like this, and honestly the rest of the bits as well;)

But that's all on the sidelines from the fact that my budget right now won't support a $120 gearbox shell;) And if that was the only way to complete the build I'd likely just decide to go a different direction or build my M14 further;)

I've heard allot of good things on the JG box from several people now so that's good news, I just ordered sorbo by the sheet to do a little custom building with the cylinder head. And likely start with a basic spring till I get everything working 100%, then I'll toss in the heavier spring and the STS and finish the build up. My other reason for wanting the STS or some reinforcement is the temperature that I play in during the winter months. I try to play down to 10F or sometimes lower since our weather sucks and if you don't play in those temps you don't play;) So I'd like a little more peace of mind using this in the cold that I won't have some sort of failure because of the brittle nature of pot metal in cold temps.

I do think that I've got a plan though to run both and see how it works out. I appreciate the input and anyone else with other info would still be appreciated.

Luke