Zarrin

Before delving into the guts of the gun itself - try removing the stock tube which is retained by a bolt that goes through to the spring guide - retest with the stock tube detached and then come back to us. Also make sure you are testing with a fully charged battery - an 11.1v if you have one. If you have a multi-meter test the voltage coming off any batts you are using.

So i re-shimmed the bevel today with the above method. I ended up adding one of the very fine 0.1mm shims to the total with 1x 0.1 on the 10 tooth side and about 1mm worth of shims on the broad side of the bevel and results seem very good tbh. While it doesn't sound much different, you could see originally the pinion was riding with a gap between the teeth; the rearrangement brought the pinion downwards sitting nicely into the bevel teeth. I also found that with the new shim config, backing the motor height screw out a 1/4 turn gave the new sweet-spot. The optimal pinio

Yeah, it's funny that though - this Lonex ultimate setup is probably the best sounding cycling I've ever heard, it's so brisk and clean .... like a 'tk tk tk' sound, pretty much zero whine or grind; this is why I was slightly surprised to see the wear building up on the pinion gear.

Yeah, one would hope you'd be able to mesh a pinion and bevel both made by Lonex together - will see, might try this evening, if not saturday. One of the frustrating things I've found with shimming is it's easy to throw semi auto out the window if you shim the bottom side of the sector too high - the COL section that get's pushed down by the sector's protruding peninsula, is semi grooved meaning that lower chunk of the COL is usually only half as thick as the overall thickness of the piece, so if you shim it up from the bottom too high it sometimes wont engage properly with the sec

Cool. I'm guessing the shim job on the other two gears isn't much different to how it would be done otherwise, seeing as the meshing of the spur and bevel is rarely too fussy. For sure, one of ways you wanna test that is once your done, close up the shell with a couple of screws and all three gears inside, and spin the gears with a finger through the cylinder port. Ideally you want them to carry on spinning a bit after you let go; if there is resistance when trying to role them or if they stop spinning the moment you release them, they are probably pinched off a bit somew

I had the CA M15 open the other day - I run a Lonex ultimate GB and an A3 motor inside it (So maybe not so CA any more.. though that's how it started off life). I noticed that the pinion gear was starting to see a little wear - nothing that will take it out of action any time soon however it will certainly die eventually if it carries on getting gnawed like that. Honestly the shimming in the Lonex is really good, I made a literal single shim swap around on the spur gear to space out the spur and sector a tad, but that was it, best shimmed GB out the factory I've ever seen. I remem

Damn, I wonder if the type of firearms license they will deem necessary is the same type you need to own an actual firearm; pretty messed up if it is. The thing that disturbs me most about that notice is the position of that carry handle and the absence of the lower quad rail - I am well and truly triggered right now. 😏

Hehehehe 😝 Mate from the purely technical stand point it's bloody genius! Bagsy, not the one to try it out first! 🙄

Yeah, I've built and tuned bearing spring guides out of the old one piece ACM steel guides before - very good way of tuning fps actually, you just gotta make sure that the piston will allow any mods you do to pass through freely otherwise you'll get a lockup very similar to what I had with the above case. You actually got me thinking though, you could probably tune fps by injecting hot glue into the piston 🤣 Maybe lather the canal up with some silicone grease beforehand so you can pull the newly formed rubbery plug out if necessary - but I mean that would probably work tbh 😅

I would imagine @Davegolf is correct about it being another variable that could effect the fps slightly. But I mean on the same or even greater merit it could be any of the below: - the spring guides which could have a different thickness of bearing washers, - the air seal of the entire piston/cylinder/nozzle section - the hop components. Mk18 has a soft rubber flat hopped inside the red metal ZCI hop unit, and the MP5 has a macaron/omega set in a bog standard JG hop unit. The answer is probably in there somewhere 😵

The Mk18 is using a 3/4 type cylinder - I'm not certain about the MP5 off the top of my head, though I would imagine Its also go a 3/4. I always try to keep the cylinder type matching the barrel length. From what I understand though the cylinder type should not have all that much impact on FPS, it's more about volume capacity matching the barrel length.

Yeah, and had quite an old misconception of mine corrected in the process - thanks fellas!

Ah du reckon? maybe your right, I always assumed it was an attempt to seal the entire chamber off thereby at the very least improving fps consistency.

So before large dial rotary m4 hop units were doing the rounds, I used have a hand full of those red element hop units. I liked the idea of having that O-ring installed on the lip, always felt like a decent idea for air seal optimisation. However the concept doesn't quite work when you throw one on yourself because most hops don't have that pre-molded groove for the O-ring to sit in, therefore instead of sealing around the GB casing it just gets smushed to the back of the hop unit thereby pushing the hop ever so slightly away from the GB. I do the same though with teflon tape

Finally came back to this GB rebuild and have now finished it to a decent standard - not perfectly however and I'll touch on that. So all of the issues I encountered in the OP have been resolved: Diagnosis; as the stock was being screwed back into the spring guide, the spring guide was being ever so slightly dis lodged from its grooves (very odd seeing as the process of screwing that bolt into the spring guide should be pulling the guide towards the back of the GB, thereby giving it no way of dislodging ). Anyway what that meant was as the guide was gett