I can’t tell you how many times I’ve stood in the shed thinking “I must have something for this”! Normal bloke behaviour!
Have fun with the gen9 box, fitting SHS gears in them is not the simplest, but it can be done with a little creativity!
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18:1 SHS gears are in the ACR… genuine ones too. Along with the War Interest 480 long motor and an M90 spring. The gears went in with minimal shimming, @RokSolid I’ve used these in a Gen 8 build before so the usual clearance issues with SHS gears I’d already addressed on the lathe. This build was easy peasey 
Target was 270FPS, my go to for accuracy and stress free pewing. Here’s the chrono reading using WI red gels, which are on rhe smaller side, so I’d expect higher with Ultra Elites. Half a mag was between 260 and 275, but the gels certainly ain’t fresh so I’ll put the variation down to that.
The motor plate needed a little height reduction due to the longer 480 motor but a bit of needle filing sorted that. Might slightly shorten the adjusting screw too now I know where it’s final position is. The J9 shell should be okay with the lower rated spring, if it ever goes Chernobyl it’ll be MK H92 time.
Very happy with it for now. Should be bulletproof. Looking forward to seeing the results of the mods on your ACR, RokSolid. Solid little units for sure. 
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I used to modify the Gold colour heads by slotting out the holes, but only used them if required for tappet travel, otherwise the old Blue type were an easy drop in design, but very difficult to find online. 
Excellent work mate and is looking good, working good, and with a few guitar parts fitted… Sounding good! 
Love that ACOG too!
Exactly the same as the one on my DMR. 
Thanks, Doc.
I tried an LPVO on it for a while… didn’t groove on it, even if it is a little more suited to a DMR. It’s back on the M14EBR again.
Much prefer the look and weight of an ACOG on this one. 
Sorry, I got my brain muddled again!
I have that same ACOG on my full metal M4, NOT the ACR DMR, which is fitted with the BUSHNELL long scope! 
I can see why a metal outer barrel is a very good thing on these ACRs. 
Muzzle droop is a real thing on mine. It’s not that the outer’s not steaight… more to do with the poorly moulded 14mmCCW thread on it. No amount of tweaking will sort it out.
So for now it gets a short flash hider, but it’s looking like I’m going to be removing that plastic piece on the front end of the outer and replacing it with an alloy jobbie. I’d like to run a suppressor on this and nothing triggers my OCD more than lines that just aren’t right. 
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I have found the same issue on mine, but it points ever so slightly upwards!
Long or short…
Hard to tell if it replaces both standard pieces or barrel or just one… thinking I will opt to the short version and if it shortens the barrel then so be it!
As side note I will have a video of the initial basic upgrades on the toobs soon. 
From the measurements listed on x-force site the short one is a little shorter than standard, and the long one is a decent amount longer.
Video of my initial upgrades experiment…
Next when I get time will be to go all out with the MK H92 gearbox, and a brushless motor!
I still enjoy making a cheaper blaster good for not much money, really don’t need to go further as I could still have loads of fun with it as is!
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Then throw a bruismaster barrel in. haha your wallet is empty and urrm I had to recorrect that cockamamy BS barrel. Yea variable fkn dia allright it’s not even machined right to start with the example I had to fix 
Bin
Gotta be a way to use a standard alloy outer barrel with the gas block grooves machined in it.
Wouldn’t be too dificult to hook up the new alloy to the 16mm end of the rear outer barrel. Knock up an alloy coupling adaptor that’s 16mm to 14mmCCW. Should be able to dial in whatever length barrel that suits with these.
Could do, the og outer used to be available on ebay and chgbb. All gone bye bye now so might have to get your skills in to play At least you have something to work with for a starter
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Where did you source that brass cylinder head? Thanks
ACR outer barrel sorted… no more droop. 
Was lucky enough to find a spare alloy outer barrel with an O.D. of 15mm, the diameter required to fit the plastic gas block, in my box of loose parts.
So found some alloy tube the right diameter to act as a coupling, cut the alloy outer barrel to retain the standard Jin Ming length, judicious application of epoxy and flat black paint.
Same overall length as OEM, dead straight, 14mmCCW thread. Easy to see in the photo below how the original plastic piece is warped, not concentric and just plain shite… binworthy.
Scrap binning it, I’ll be cutting it up so I can use it on the next candidate for a 14mm reverse thread transplant.
Rigid enough to maybe eliminate the barrel stabiliser but think I’ll run it anyway just to be sure. Cut from 10mm rubber, works well.
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No idea, had it spare from many years ago! Have not seen a brass jinming head/nozzle for sale in a long time.
@Friendly_Fire that’s an awesome use of old parts… I will have to look through my ancient spares box and see what I turn up!
Cheers, @RokSolid … I’m done modding this now… Looking forward to seeing yours develop.
If I really wanted the original look it’d be easy to put a couple of short lengths of 15mm ID tube in front of and behind the gas block… build it up to OEM diameter. But unless some of that throws itself at my feet it’s firmly in the “can’t be arsed” basket.
Don’t know if you’ve noticed but the fake gas block does push the barrel downwards slightly. JM kinda screwed up a little there. But at least the barrel itself is straight now and the supp doesn’t look like it needs Viagra.
I hadn’t noticed the barrel pushing down on mine, maybe fixed on the later j10r model? I’ll have a closer look at some point. Looking like next weekend I’ll get some time on it.
Ladies and gentleman, there we have it. Well done sir 
Received the short X-Force metal outer barrel yesterday. It looks to be a fitting replacement… but doesn’t have a 14mm ccw end, rather has a small 19mm outer with a hollow end that is a straight tube- think gen8 style.
Little disappointed, but I have a 19mm to 14mm ccw adaptor piece… somewhere! I’ll epoxy that in once I find it… or just epoxy a small extension in, haven’t had much time to play with it yet.
It does neatly fit a ldt universal riser style hopup, could then run a 19mm mount suppressor… I’ll have a fiddle this weekend.
The first stage is done… nylon box out of the acr, changed cylinder to suit shorter barrel, metal trigger from the acr metal parts kit went in as a bit of a homepage to where it’s innards came from.
And messed with the front end for a bit of a laugh. The little round handguard is filled with a knurled tube held in by big o-rings at the moment.
Will print parts to hold it at the back, and design and print a end cap to fit the tube, screw onto the barrel and be a hopup.
Ran out of printer filament printed gel sorter adaptors courtesy of @DChapo post on thingyverse… so the end cap has to wait.
Next, the mk box to the ACR!
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