Retro Arms CNC Machined Aluminum Rotary Hop-Up Unit for M4 Series Airsoft AEGs

"I installed the retro arms hop up chamber in a Krytac CRB. It fit right in without any modifications. It was well machined and seems to adjust just fine. Has alot more precise tuning than the standard krytac hopup unit.

I've had the prowin, VFC, Krytac, Prometheus and the retro arms. Have to say my top two so far for adjustment and fit and finish are Retro Arms and Prometheus. Retro arms is all aluminum as opposed to the Prometheus having some plastic.

"Stupidly good hopup, like other reviews said you will have to trim your bucking but that does not affect performance in the slightest. The grooves inside the turn wheel make it a super solid turn that won't wiggle out of place during use. Also once you screw in the nut for the inner barrel it makes it tight with no wiggle at all. The only thing I had to do was shave my outer barrel a bit to make it fit inside the receiver, but that took two minutes with a file and it was perfect. Beware like other rotary hopups it stands high so it might be to tall for your receiver. All in all it reminds me a lot of the action army hopup for vsr10's in how it operates and once I get this thing out to areas bigger than my local cqb place I'm expecting easy 275ft+ shots on a r-hopped barrel/polarstar setup. 5/5

"Stupidly good hopup, like other reviews said you will have to trim your bucking but that does not affect performance in the slightest. The grooves inside the turn wheel make it a super solid turn that won't wiggle out of place during use. Also once you screw in the nut for the inner barrel it makes it tight with no wiggle at all. The only thing I had to do was shave my outer barrel a bit to make it fit inside the receiver, but that took two minutes with a file and it was perfect. Beware like other rotary hopups it stands high so it might be to tall for your receiver. All in all it reminds me a lot of the action army hopup for vsr10's in how it operates and once I get this thing out to areas bigger than my local cqb place I'm expecting easy 275ft+ shots on a r-hopped barrel/polarstar setup. 5/5

"Got this from brill armory, but thought I'd share my review here too. I think this is the best hop up chamber ever, better than prowin. It features everything the prowin has, but is actually CNC'ed, has little notches to prevent accidental rotary movement, has a collet nut to provide absolute solidity, and is fully 7075 t6 cnc aluminum. Love everything about this thing.

"This is an amazing hopup unit. Sadly, evike forgot to note that this hopup chamber uses a shorter bucking than traditional buckings. Every other website that sells these does mention that. Other than that, I love how this bucking performs. I think it is sturdier and provides a more consistent hop than other units due to a small spring pushing the hopup arm.

"With a lot of works, it fit in the KWA Ronin Series, you must work in the stock nozzle too... Just have to work in the upper part of the Chamber and in the nub arm...
It work fine and its better than the stock Chamber

"As a Tech for my team using KWA and Ares rifles, I've heard a lot of back and fourth from team members about which is better. Personally, I've found it depends on the build. For quick adjustments, a pro-win is the obvious answer (Please Look at my review on the Pro-Win for details.). The Retro arms dial is very stiff but this benefits long range, tuned builds. My personal build, an Ares M110, (one of these tuned builds) uses the benefit of stiffness as it has never lost pressure on the nub in an engagement at 200+ feet (100 meter shoots are possible with this hop up with .4bbs and a Tight bore of your choice), something important when you are counter snipping. I would recommend Flat hopping on both builds if you want to get the best performance. (Unless you can R-hop) Either is a good choice. But After my previous issues with the pro-win (late 2017), I will be sticking with retro-arms until they increase QC.

--Retro Arms-- (Good for long range builds)
Pros:
Stiff and doesnt move once you set it.
2 ways to tension the barrel,
large window for the nub
Cons:
Doesn't Fit stock KWAs (Vers 2.5+), Some G&P, or most Ares without cutting


--Pro-Win-- (Good for the everyday user, and with a little work, long range builds)
Pros:
Fits most TM style guns
Easy to adjust for quick games
Large window for nub (slightly smaller than retro arms)
Cons:
Doesnt fit Stock KWA (Vers 2.5+) or Ares (M110, cant speak for others)

Nash,
Red Devil Works Tech

"The hop dial does not turn smoothly, very difficult to adjust once it is already installed in the receiver. Better off buying prowin or something similar in design...heck your stock hop is better than this one.

"Ok so I did have to trim my prommy flat bucking, but other than that this hop up is damn good. The wheel tends to be harder to turn, at least on mine, towards max hop, but normal use will make it easier and it prevents any hop up walk you might see.
Already ordered 2 more.

"love the quality, love the arm options for the nub, built nicely. Has a window to see how much hop your nub is applying.

Extremely hard to turn up or down on the adjustment. this is VARY hard to turn.

I could not run this unit because the Feed shaft for the BB's is TOO LONG. I broke 2 mags before i realized this was an issue. I tried to shave it down, and eventually it became too short. thus not feeding BB's at all. I believe this may have been a factory problem. but.... who knows.

Krytec , retro arms, Prommy purple, Omega hop up nub. Couple different mags.

"pretty bad overall. bought it for my krytac lvoa build. was planning to use it for a flat hop mod for my prometheus tight bore barrel. you have to cut the hop up bucking in order to make the barrel clip fit in. there is no gasket to complete the air seal with dial. also the c-clip to keep the dial in is incredibly weak, making the whole set up wobbly. super disappointed with it.

"Looks like a well made hopup, but the window for the c-clip is too far forward, which means the c-clip pinches the bucking. Then I cut the end of my bucking to see if that would work, the c-clip STILL doesn't lock the barrel rotation because the window for the c-clip is waaaay too far forward, meaning that I'm going to have to spend 100x as long CAREFULLY assembling the damn thing because the collet nut tries to rotate the inner barrel when you screw it on.

I think it's better made than the prowin, apart from this GLARING design flaw...