While this is generally true and advisable, I've been using the same un-tapered (or very minimal) G&P nozzle in one of my guns for ten years now, and it's never given me any problems. When in doubt, TEST.

So like question, what is the recommended method to shaving down a nozzle? What tools should I be using to shorten and taper?

@@KoujiRenamon i put the nozzle on a drill and then use some sandpaper like a makeshift lathe. round it off little by little until the nozzle is tapered enough to be making good contact with the bucking. Do not over taper or else you would make the airseal even worse. Test by inserting the nozzle into the bucking lips by like 1mm and see how well the lips wrap around the nozzle (no innuendo intended)

be careful when tapering. overdoing it will also make the nozzle failed to mate with bucking lips and will drop the fps

​@@n8taing61230° or 45° angle?

Same here

Most likely tappet plate, they do wear down where they contact with the sector gear

Check also the magazine you are using.

i also have some problem and took me years to solve. basically here it is: 1.) bucking lips too tight inside the chamber. could be due to thicker, harder bucking, or disfigured chamber. test it by putting one BB, and push it with something. if it hard, thats definately the issues. change the bucking into softer one, or file the inside of the chamber, or sand the bucking lips with very fine sandpaper 2.) not enough tappet spring power to push the BB into the chamber. this may due to week spring or too much upward tension of BB by mag spring. the fix is by strengthening the tappet spring by cutting it 2-3 coils. but dont make it too harder or tappet will break. or reduce the strain from BB from mag by filling it not too full (midcap) or dont wind it until too hard (hicap) 3.) nozzle diameter too small and create too much play inside the chamber. if the nozzle to much play, it will misalign when being pushed by BB from mag and create issues such as misfed, doublefed, or fps loss. use the matched size nozzle for your chamber or shim the chamber internal by using thin sheet metal + power glue 4.) nozzle too tight also will create a lot of issues as mentioned above. fix by the opposite as mentioned above. basically, thats all the problem that for me become misteries for past 8 years. i always focus and gearbox and compression part, but never realize that nozzle, bucking, chamber ( and receiver) is as imortant as the gearbox set

@@ebehdzikraa3855 I was having double feed issues with the maxx nozzle (21.4), so I went back to the stock CM16 nozzle (21.34) and the issue was gone, but yeah, I could kinda solve by not filling too much my midcaps, but I never had problems with the stock nozzle even full filing my mids, because it sits tight enough and doesn't have any wobble (unlike maxx nozzle), the only problem now is that it doesn't have a o-ring, so I lost a couple joules. Now I bought a VFC polymer air seal nozzle to see if seals nice without causing me midcap syndrome (umbrella armory guys uses it a lot so I'll give it a shot)

Nice you must have a whole list of good to knows :)

@@WazheadBoci it depends on which generation of ICS gun you're working on. One really weird thing I found with the forward assist spring release series was that I discovered a recurring fault in a high speed set up (DSG 10.1 gears, was running about 46rps at 310fps set for .25s, single stroke wanker gun basically)...the fault was that the anti reversal extension would shear off the part that would be acted upon by the forward assist. Dremelling a little material from the lower gearbox case and the upper gearbox case and shaving about 2mm off the back of the tappet plate so there was no way any of these things could contact the ARL arm over the entire distance it could theoretically travel and it never happened again. ICS guns have pretty poor AoE when you change the sector gear and piston - stock ICS pistons appear to marginally longer than TM spec so it's probably easier to think of an ICS M4 gearbox upper as having all its guts a little further forward in relation to the sector gear axle axis. Very small difference I had no end of problems seeing very aggressive piston wear within only a few thousand rounds with TM, Deepfire and Guarder polyacetal pistons with the same piston head without AoE correction. Most guns need 0-3mm adjustment, ICS M4s it's closer to 4-5mm. That's significant and I believe contributed to their early rep for not being easy to upgrade. The material they use for the stock 'nub' in the hop is garbage, the actual sleeve they put on the barrel is adequate (for UK power levels). Because their lower receivers are longer than normal behind the pistol grip this can be an issue for some brands after market grip with an extended beavertail design where an extension of the grip would ride over the web of your thumb. Receiver threading can be a bit of a PITA for aftermarket barrel nuts (wire brush and anti seize are your friend). Plastic hop unit 'wings' that slot into the outer barrel are top fat (tall) for the slots in G&P barrels so you're either dremelling/filing the barrel or the hop which has a risk of nozzle/hop unit misalignment if you get it wrong (measure twice, cut once). A wobbly stock ICS outer barrel (they're technically 3 piece between a hop housing base, mid barrel and then an extension that the foresight attaches to that can be adjusted in length slightly) can be remedied by drilling the pins and screws out and threadlocking grub screws in place, think I've used very short M4 grub/hex screws in the past. That was more around exploring how to make the gun more accurate and obviously you want everything in the upper part of the gun to be as locked together/rigid as possible.

Can also be a tappet plate problem, have you changed the air nozzle?

Can also be a tappet plate problem, have you changed the air nozzle?

@@marinusdedreu3833 it's all stock.

Looks like the airseal doesn't concern him although in this case you would want to assemble your gearbox without gears, spring and spring guide with piston placed in the rear position, then put gearbox and barrel\hop-up assembly into the build as much close to the fully assembled gun as possible with only exception being having a window to put a long rod and push the piston forward while keeping the muzzle of the inner barrel sealed with your finger, if the airseal in the cylinder and between nozzle and hop-up rubber is good - you won't be able to push the piston all the way forward, if there will be a hissing sound and a slow air leak - an extra 0.2-0.4mm of nozzle, more blunt shape of the nozzle front end or the hop-up rubber with thicker lips might help out, if there is no airseal whatsoever the gap between nozzle and rubber is major, you will even probably see the light from the feeding valve of the hop unit if you will point a flashlight into the inner barrel

@@lauranceberiya1314 is there meant to be space for the BB?

@@lukeskywalker9438 If you only achieve airseal when nozzle doesn't go back far enough to let the bb in the chamber you need a nozzle with more blunt shape of the front or a rubber with thicker lips

Also in this boat

do it manually by pushing the fully assembled chamber to fully assembled gearbox and blow it with your mouth. if it no leak, thats a correct mating between nozzle and bucking. but be careful, good mating frequently will result in misfeed due to the nozzle was not moved backward enough. my solution of this is by make sure the backward movement is enough to clear the BB first, then filling the front part of the tappet plate (and also camming leaf on the back, at the sector gear axis during full forward position). this will make the nozzle move more forward without sacrificing backward movement. but dont file it too much since it could make the tappet become flimpsy and ruining it

I am having feed issues. Can the SPR work with 20.75 with Maxx hop-up pro? Thank you

You don't. Best tip I can offer is to basically put the gearbox together but without the cylinder, piston or pistonhead, so you can reach the tappet plate from where the cylinder usually sits, and then hold your hop-up unit against the gearbox.

Have you fixed this? How did you shave it? I have same problem with a split hop up sr25, im planing to sand the tip of the nozle off bit by bit test it after each 6 sanding strokes prety much

@@epicmexican7153 I'm waiting for the replacement nozzle still, I live in Belize shippin takes a long time here... check out this video skip to 3:42 to save time kzfaq.info/get/bejne/bqdhaqybndHco4k.html

@@epicmexican7153 Also although Ive seen a few guides of people shaving/cutting their nozzles I've yet to see a diy method that gets it smooth enough for me to fully trust the nozzle wont somehow create inaccuracies...

Nozzle sits on the tappet plate inside the gearbox. You have to open it to replace them. But the nozzle sticks out of the front of the box. It then connects to the back of the hop up.

To me, it's a must :)) Punching through the bucking hole is a must

You just loctite the threads to keep it from moving?

What was the problem with the m4? I have a shs nozzle mounted on a maxx model camera, and some shots go up, 5 normal shots and 1 up shot (hop up high)

I have the same set up (Maxx hop up and SHS nozzle), did filing down the nozzle completely solved your feeding issue? (For me different mags have different issues. Some do not feed at all, some get the bb jammed half way and on the second shot it shoots (every other trigger pull it actually shoots the bb)). I am wondering if filing down the nozzle, or removing some of the hop up springs will resolve problems. One thing to point out is that when I hold the mag at certain position/angle, feeding issues disappear. Please let me know what you have done to solve your issue. Thanks 🙏

Don't glue it to the tappet plate, there is no reason to

@@Zeryth960 Ryan seems to do it, reason being that the nozzle might not be seating on the tappet plate without moving slightly, which can lead to fps consistency issues IIRC

@@Zeryth960 I glue it on every gun I work on, there is lots of different gap sizes in nozzles for the part that seats it to the tappet, and lots of different sized ridges on tappet plates. This mitigates those variations

Man I still wonder

Try putting a thin rubber o-ring on the rear of your hopup chamber. The part tat goes into the front of the gearbox shell. that wee bit of spacing is sometimes all that is needed. You can get several different thicknesses of o-rings to try out.

Could also be the sensors somehow not picking up at the exact same time. Also full auto would make it have random positions

That should not be the case since the tappet plate is released by the sector cam at always the same moment relatively to the release of the piston. This is a problem with your timing and other parts, not the gate.

I ran into similar before and corrected by adding a sector delay to the gear. Gives a little more time for the bbs to feed if it’s a feed problem. Or check to make sure your tappet plate is moving free, it’s pretty easy to misalign them on some gear boxes. Another spot is your piston seal.... lots of spots to look at....

Also, look at the tappet plate return spring. If its worn out and not very stiff, then the return of the nozzle might be different from shot to shot. Also check to make sure that there is nothing blocking the tappet plate from returning fully to the forward position.

Measure stock one and go onto retro Arms website and order that length, they have air nozzles in any length standard bore size and bore up size

Marinus de Dreu the problem is I piled up the front end in a shattered the original. Totally my fault accidentally hit the trigger doing a spring swap to make the fields limits. Made a hell of a mess..... rookie mistake 🙄

You could try taking out the piston and spring (maybe the ARL too). Then slide the gearbox into the upper and cycle the gears with something through the pinion hole

If the muzzle of your inner barrel extends beyond the outer barrel and if you know the piston is fully forward, just blow down the muzzle end. You'll be trying to push air against what is hopefully a seal between hop rubber/nozzle and the piston head sealing against the cylinder head outlet. And because some people on the net are complete maroons...mags and battery out of gun before doing this.

I know it's a year old but my sr25 the matrix one has this issue, it double feeds and only shoots 10-20 feet, after the right nozzle it's shooting way more.

You shouldn't be running into pme with that setup, that's actually really interesting

Did you correct AOE? Put a MOSFET in with active breaking if you can't figure it out

you get terrible fps due to poor airseal

See the comment below about tapering the nozzle after sanding

Go to retro Arms website, they have any length air nozzle, in both standard, and SBU (standard bore up)

@@marinusdedreu3833 Turns out they are the same exact size, i didn't use very a precise measurement device. Finally got everything shimmed and closed up, hopefully it works