Guarder Bore-Up Cylinder Set for Airsoft AEG Gearboxes (Model: M4A1)

"Installed in my super custom CYMA M4. I have been considering getting a bore up set for a while and I wasn’t disappointed. The 40FPS increase is pretty impressive considering I was originally using a mix of ZCI and lonex parts that got a great air seal. Overall good price and great quality.

"I purchased this for my Kwa M4 sounds more powerful don't have chronograph added 469 mm tight bore 6.01mm stock barrel was 393 mm shoots flat to about 200 ft.cylinder is a little longer than stock, had to modify very small amount. Stock piston fell through the upgraded cylinder hotdog down hallway LOL.

"I don't know if it's the bore-up (doubtful) or just the quality of the parts in achieving airseal, but I've installed this in two different gearboxes with no tricks like teflon or permatex, no extra o-rings or anything, and with an AIM torque gearset, a fresh m120 and 407mm 6.03 inner barrel it consistency pulls 420-430 fps where before these gearboxes were struggling to reach 360.

"I just finished installing this on my m16 SPR mod 0 and from what i can tell all of the parts work very well, a couple of things to mention are that the oring that comes in the package for the piston head is a bit small for the cylinder so i would invest in a larger oring for a better air seal. The other thing is, when you are securing the piston head to the piston get a good grip and make the crew as tight as possible without stripping it. I though i had it on tight, but while shimming the gearbox i test fired it and the crew backed out and became loose and the cylinder head started bouncing around in the cylinder.

Pros: So far all the parts are holding up
good fit in the ver.2 gearbox
oring seal tappet plate
Quiets the slamming of the piston head against the cylinder head

Cons: Small oring poor air seal (cheap though so only small con)
screw backed itself out (may have been operator error though)

Overall can't go wrong with this if you have an m4/m16

"The quality of the cylinder and cylinder head is awesome. The air-seal is absolutely perfect, which makes me wonder why the hell a plastic nozzle in such a high-quality kit???

"The Kit is great and has a perfect air seal once it is lubricated. I didn't see much of an FPS gain, only 5-10 fps, but it is much more consistant. Overall it is a really good set and makes it a little quieter as well, this could be a pro or a con.

"Great kit except the air nozzle. It would come loose off my tapet plate when fired. I would give this set a 5 star if it came with a cnc or aluminum air nozzle. Besides the air nozzle the rest of the kit is great!!

"The quality of this set is great except for the air nozzle, it is cheap. I installed this on my King Arms Galil Mar and in test firing it the air nozzle broke at the groves where it seats on the tappet plate. Plan on upgrading your air nozzle when buying this kit.

"Let me start off by saying all guarder products I have ever bought have been of the highest quality. I would recommend going with the regular cylinder enhancement set over this. Depending on the gearbox, you may have to dremmel to get this to fit. Also boreup size parts are an odd size and can be hard to find down the road. Guarder all the way but do yourself a favor and get a regular size kit with a sorbo pad. Still a great quality product though.

"I've installed this bore up system on my sr10 kwa , from stock cylinder my fps was running around 450 on an m130 spring , now it shoots around 500 fps with an m130 pdi spring , wow! It's incredible!

"Great part, but the picture shows a cylinder head that does not have a ridge on the top (Why I ordered it). You see, the ridge on the top does not fit the version 3 gearboxes, at least not CYMA. To my dismay, the head has the ridge on the top, despite what the picture shows. I am getting tired of Evike's mislabeling and advertising/pictures. The upgrade parts seem to be the only thing they can't get right, like a different company is running it.

Cheers

"The Guarder bore up nozzle leaks air badly due to poorly sized nozzle O-ring. Remove the tiny O-ring from inside the Guarder nozzle and replace with a 0.80mm x 5mm O-ring. After fitting a correct sized O-ring, the air seal is 100%. It’s so aggravating paying so much for parts to maximize air volume only to have those parts leak air like a sieve. I have had really good experiences with Guarder parts in the past but feel very let down that sell this Bore Up kit with undersized O-ring that leaks. If you buy this Bore Up kit, pick up a couple O-rings (0.80mm x 5mm) or you will loose your mind trying to fix the air leak.

"It is compatible with the Snow wolf AUG, I had to force the piston head into the gearbox and the air nozzle barely moves after assembling the gearbox again, but since the plastic air nozzle doesn't have a O-ring the air seal between piston head and air nozzle is a joke and the idea of better "air volume" i nonsense. just go for a Lonex kit.