ak2m4

@RostokMcSpoons cylinder internal diameter varies quite a bit, from 23.6mm to 24mm. Recheck the seals on yours. Most problems stem from the piston head o-ring either isn't big enough or something is blocking the vents (not allowing the oring to be pushing out). A BS910 o-ring is slightly larger so grab one of those. The o-ring on the nozzle might make a small amount of difference but in my experience doesn't affect fps greatly, it's more there to keep the nozzle centered.

yup, there's a little business there for sure for someone as the real AR vice grips don't really fit that well for airsoft, well mine doesn't. Can get them from ali for £12 but have to wait a month to arrive.

AR vice grip is what you need but it's a pricey tool for just a one off job

That's exactly why I never did it. However I get asked a lot of questions "what is the best combination of motor and gears" etc. Of course no right or wrong answer.

I think a more relatable test would be testing each motor with 13:1 gears and 18:1 gears together to a device that measures amp draw on semi and full auto. Of course you'll need a better sample of known brand motors etc. Guessing this was for gel blasters? Be nice to see just how spring power including short stroking affects amp draw, buy hey it's a lot of work putting together something like that.

I built myself one of these a couple years ago, handheld not fixed, but every time I pulled back a spring it gave different reading. Do you get much variation in readings?

I would love to see springs measured in newtons at certain points of compression, this is what a spring factory uses and would save so much hassle. A few screenshots from the spring factory where my ones are made.

Try some grease on the spring itself. Additionally whenever I've removed the bearing from the piston head I always notice a 15 - 20fps difference with 0.2g

@Skara some fit both just don't like to say so, I know the plastic zci one does, or does with a small amount of filing around the holes

That is true.... @ModernTimes where you based?

If you went to the store and they advised you a M115 would be fine then they should have also mentioned that you have a compression issue somewhere in the gearbox or hop chamber and that needs to be fixed first. Unfortunately you'll need to open the gearbox to troubleshoot. You can do it yourself of course or try to find a decent tech. My advice, forget about turning it into a DMR for now till you have more experience, unless you want to pay for someone else to do the work.

Not an E&C, can tell by the screws, could be one of the new ZCI though.

Had a customer 2 weeks ago was short-stroking without a chrono 🙂

My advice is put the M90 back in and just play with it for a few games. Go and watch some upgrade video's on YT, so many great resources out there. Lot of people rush into upgrades but only end up breaking their only AEG. You say you want a DMR, would this be a 2nd AEG or are you planning on converting the CORE?

Perfectly put 🙂 Reason why I stopped selling mags, too many people complaining that the product was "broken" when in fact just didn't work for their particular AEG. Then sending them back all scratched up looking like been run over by a truck and then demanding a refund. QC can always be better but in this case I think it's more down to the design tolerances of the lower receiver / magwell of each brand.

Contact HFC directly

@Makis it's not the cable that needs replacing it's just the female spade connector (part that connects to the motor tab), to properly fix you'll need soldering iron, heat shrink etc. You can buy replacement trigger wiring but they aren't all the same unless you get a KA one.

does indeed sound like it's failed, you can check the brushes and springs etc. hard to move doesn't always mean decent magnets, poor motor shimming or broken bearings can cause that as well

@RostokMcSpoons Does the fried motor still work outside the gun? Did you have the wires connected the right way? Couple of things to check just in case. Some motors don't like certain FETs as well

fyi: When they came out WH gave me some to test here's the summary 2000 cycles for each motor. First 1000 were 5 sec burst, then 2nd 1000 10 sec burst. M100 spring, 18:1 Gearset SHS 14TPA Motor with 7.4v (fully charged) RPS = 18 Full Auto Amp Draw = 25 Motor external temp after 2000 cycles = 50 (centigrade) Warhead Ultra Motor with 7.4v (fully charged) RPS = 27 Full Auto Amp Draw = 20 Motor external temp after 2000 cycles = 35 (centigrade) Not sure if it's like this across the board but you can see here better efficiency, lower temps and higher rps

AEG for sure 🙂

this is the most common reason

Invicta Battlefield are pretty close, you might have better luck posting on their FB page

@EDcase Yup a Polish customer of mine did this with one of the "Polish man with a van" chaps and sure enough wasn't cost effective. Only really useful if it's a something not available in the UK. I'm due a phone chat with a new HK sea freight agent tomorrow to see what the situation is with container shipping.

@Speedbird_666 thanks. the 520 rnd mag is wheel based for anyone who is interested.