It always been 7.3 on the hard hitting long boys and 7.5 on everything else for me.
Putting a 7.6 on the MP5Ks makes a lot of sense… better volume on the barrel, maybe less porting. Like a juggling act between which one’s going to give the best result.
I like it… Dr Karl stuff. 
That was my thinking in such a short barrel, you go bigger ID.
Long like my 20" built before available M16A1 I went 7.3mm and that is accurate as the cylinder volume can’t do the 7.5, runs out of puff before exiting. 310fps on a shock horror well cylinder head(extra volume with well cyl head), 1.18mm AG spring. She’s a humdinger thanks to Rattlers guidance /help on that one heap of shit I resurrected. Still going on og APS silveredge too because it is soft and does not hammer. I don’t dry fire either or try to avoid it.
It makes sence to me as the bigger volume of a short barrel with 7.5mm id you get similar performance to a much longer 7.3mm, with your cylinder and porting as well if you get that all about right. Then you can get leaky cyl heads, orings, nozzle and throw everything to the curb and easy to get confused and where to attack to get it right.
There’s something in that Dr Karl I swear 
Took the broken one into iHobby and they swapped it over. They even found the problem with the selector that I was working around . Impressed with the service
Did iHobby upgrade from a house to a store these days?
@Wombat Do you know what the failure was?
I’m holding off springing for one of these until I get a warm fuzzy feeling it’s not going to go all Chernobyl on me and cover me in Jin Ming juice… 
Didn’t get to pull it apart. I think it could be a motor height problem. It is exacerbated by imprecise positioning of selector for single fire. On single fire you can hear the motor rattling a bit as it stops rotating
Is that on the replacement or? How is the replacement?
replacement is fine - 180 to 200fps. Has same lack of detent with fire selector and the rattling on sustained semi. It’s still good vale for half the price of the LDT and a good base to build it up
Would have they swapped it for a mp7, if you preferred them?
I reckon your right, pull it apart, upgrade, then you should be on solid ground…
Thanks, good info. Now I just need to make my bank account great again 
Already built an MP7. Might build MP7 after I’m finished with this one
very good! I’ve still got to mail mine to them but should get to it tmrw.
picked one of these the other day and am quite impressed with the quality for the price.
For anyone intending on modding one, something to note is that there is no motor height screw(at least on mine). The stock motor shaft is longer than a standard 480 (compared with a warhead and xforce motor). I have tried both a metric threaded screw and grub screw without any luck as there is not enough plastic in the baseplate for the screw to hold.
I’ve temporarily overcome this by using a couple orings as spacers.
As for performance, as mentioned previously, it’s pretty dismal with the cylinder/barrel length combo. But is pretty easy fix.
Currently mine is running 16:1, warhead 20k, nylon slr cylinder (I think it’s roughly 70%) 7.5mm ausgel barrel & LDT hop up hidden with a short suppressor (barrel and hop is roughly 23cm and just what I had laying around that fit without having to measure/calculate anything) and a slr cylinder head /nozzle.
On a m100 it was doing fairly consistent 290-310, but have swapped to a m90 as I’ll be testing this weekend at a 300fps game
Other things I’ve found:
Wow, thanks for the detailed info. Guess I scratch that off my birthday list…
Tbh I was very surprised at how nice it feels for the price and I’d compare it to the LDT nylon MP5s at a fraction of the cost.
Another pro for this is how the mag terminals are. It makes for taking out the gear box so much easier without the worry of snapping spring terminals.
Even with the stock gears and motor it’ll only need a few things (cylinder/nozzle/barrel & spring) to make it a decent lil cqb performer. For mine it’ll probably end up being hpa’d. But for now will run it as I’ve listed with a change of spring for different fields.
Hmm the good ole JM like to do things different seems to be still in play.
There is a introductory thread we encourage new members to post in if you can.
Thanks, far from new, was on the old forum, mostly just lurk in the shadows though.
All good please yourself Not that there was anyone named Nam on the old forum.
Talk, dont Lurk…!!
We don’t bite…!!
Sounds like you can contribute a fair bit to the forum…!
