I talked to a guy on the Gasguns forums about the Magpul ACR and he sent me a Pm about why he hates it so much. I can't confirm if all of this is true but it sounds legit enough:
Re: ACR Bad
Sent: 13 Feb 2011, 00:50
From: Dynamo1RPC
To: the_silencer
here's a brake down of the problems and what i have repaired.
i'll work my way to the gearbox from the outside in.
1: upper receiver is painted. they claim it's anodized and indeed it is, but only to level 1. looking at the inside surface, you can scrape the anodized surface off with a finger nail. same goes for the paint on the exterior of the receiver.
2: the trunnion is made of cast zing/aluminum alloy, and painted gray. the barrel flexes too easily.
3: the front flip-up sight is not used in the production version of the ACR, it was only in the prototype and dropped for better sights.
4: the inner barrel is cheaply made, the outside surface is rough and not uniform in diameter.
5: hop-up C clip that holds the inner barrel from rotating or moving forwards of back is made of plastic and came already broken. all it has to keep the barrel from moving is a tiny 2x3 mm tab on the C clip.
6: the proprietary nozzle is made up of two cast plastic halves and is warped. the nozzle fits onto the cylinder head really loose and doesn't seal well if at all.
7: they use a silicone based hop-up sleeve. using silicon oil anywhere would cause the sleeve to swell. (sleeve came already over saturated and swollen.)
8: the gear box shell is proprietary.
9: they use lock washers on the screws, when the screws used are countersink head screws. (there's plenty of room to use torx bolts)
10: the cylinder head is cheap plastic, and it's warped really bad. horrible air seal.
11: the piston is also cheap plastic, and the metal tooth is not the same specs as other manufacturers. the piston tooth has dug two nice deep gouges along the inside surface of the cylinder. (was only noticed after trying to find why there was so much metal filings inside the gearbox. the whole gear box was de-greased to remove all the filings.
12: the sector gear was out of spec. the diameter is .02 larger than any other manufacturer, which in conjunction with the larger piston tooth, caused the piston to get wedged between the sector gear and the upper wall of the gearbox. completely ceasing. (after removing the motor and releasing the anti reverse latch, a hammer was needed to knock the piston forward.)
13: the spur gear was warped, like a vinyl record left in the hot sun for a few hours. which indicates a really poor tempering job.
14: the bevel gear was out of spec. the hight along its axis was larger than any bevel gear i ever tried. it didn't have any shims on it as nothing could fit.
15: trigger & switch assembly - interesting design, but flawed execution. the switch used looses connectivity when the gearbox cycles due to vibration and shock forces from the slamming piston rattling the internals of the switch. this caused the gun to hick-up while firing in full auto and semi.
16: motor and motor cage - when operating the electrical terminals of the motor contact the motor cage. the cage it self does a shit job of preventing the motor from rotating. so there is arcing that shorts out the motor.
i have replaced all the gears, bushings/bearings and shimmed them.
the piston and cylinder along with the cylinder head have also been replaced. piston no longer ceases, and the air seal is great.
i also threw out the plastic proprietary nozzle and made a new one out of a solid piece of 6061 T6 aluminum. fits on the new cylinder head perfectly and seals completely.
replaced the original motor with a G&P motor until a new one arrives. the trigger switch issue has yet to be solved, but i have some replacements on the way. if these new switches don't solve the contact issue, i might have to re-engineer the trigger assembly to use a tact switch. bypassing the switch, the gun cycles perfectly with the new parts.
i have yet to repair/ replace the barrel C clip. might have to make one out of brass of aluminum and secure the barrel with grub screws.
going to replace the stock inner barrel with a 6.03 mm tight bore barrel from Prometheus.
so far the way i would rate the MAGPUL PTS ACR would be as follows.
aesthetics - 7/10 yea, it looks like an ACR.
exterior build quality - 6/10 fucking painted when it should be anodized.
reliability - 3/10 did not work right out of the box.
internal parts - 1/10 seen better quality parts in first gen JingGong clones.
cost 2/10 for what you are paying, this gun is a piece of shit. cost almost double that of other guns and has probability the worst internals i have ever had the displeasure to work on.
overall i rate it 38% out of 100. there are far better AEGs that cost half as much and would last ten times as long as this scam of a gun.
Also, if you want a QD gearbox, get this:
http://www.khmountain.com/airsoft/pr...oducts_id=2351 It appears to be a clone of Ares/Star so you will prolly need to modify the receiver to fit.