Annoying M4 hopup
A loose and constantly out of adjustment hopup dial is one of the most common and annoying problems with almost every brand of M4, M16, M733 or AR-series airsoft rifle.
If you have ever owned or used a M4A1 or similar AR-series AEG, you know how annoying it can be to have your hopup constantly losing its adjustment. I’ve tried dozens of field “repairs” including chewing gum, stuffing material under the dust cover and electrical tape – most of which only create a temporary fix. What I’ve done with my own M4 style guns:
The lock washer (or split washer) fix
My favorite fix is to find a small lock washer that will apply extra pressure to the hopup dial/wheel. I’ve used several types of washers and found that split washers do a great job of adding extra tension to the dial, allowing for a much more precise adjustment – that stays in place!
Replace it with a new unit
There are quite a few versions of replacement hopup units out there, so I can’t make a single recommendation for every version/model of gun. In some cases a replacement may be the right solution, but I would start with the washer fix unless you’re having other problems with your hopup.
Replacement hopup unit from Airsoft Extreme.
Metal hopup from Airsoft GI.
If you have some ideas or ridiculous things you’ve done to fix your M4/M16 hopup, leave a comment, I’d like to hear about it. -6mm
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I had the same problem with my SRC M4 Ris. A simple lock washer solved this problem. It’s sad to see people dish out $40+ for a new hop-up when a few cents for a washer could solve it!!!
by Chip S. February 17th, 2009Thanks for posting this guys! It should be VERY helpful for those in need!!!
@ Chip – thanks for the comment. It’s really amazing how the simple fix often is the best fix.
by 6mm February 17th, 2009Awesome! i never really knew that was a problem i could fix, just thought it was a bit of play in the gears… now i can fix it! Thanks guys. Any tips for hop up setting in extreme cold?
by Wired February 17th, 2009Very cool. I just got a new SR-16 and hop-up has always been one of the most perplexing things to me. This problem hasnt happened…yet but thanks in advance for the tip when it does. Way to go guys!!
by Ian February 18th, 2009I have a JG 416, it’s almost M4, ithink you know it, so have hop-up problem i think. the BB (i use 0.25g) when leaves the barrel, go ahead to right-side-way and a bit up to approx 15 meters, and after suddenly the BB goes into the sky. sorry my english is not too good, so i made a picture, to show to you my problem, i linked my draw:
http://kepfeltoltes.hu/090219/710193307bb_www.kepfeltoltes.hu_.jpg
i tried to adjust the hop-up, but not fixed the problem that, plese help me if u can, thank you.
by Tibor February 19th, 2009Hey tibor i think your problem is that your hop up bucking has been rotated to one side causing your hop up friction to not land correctly on the bb. take the barrel out of your hop up and make sure the bucking is aligned with your barrel. If that doesnt do it, its a barrel problem. Make sure its cleaned. Hope any of that helps. -Wired
by Wired February 19th, 2009could you guys do article on how to assemble a hop up?
by Pat February 20th, 2009yeah, i would like to see a hop-up assembly-diassembly article too, that would be great.
by Tibor February 22nd, 2009I have several Jing Gongs and they always come with the same problem: over-sized hopup. The problem is that the bucking has a “bump” on it which sticks into the barrel and contacts the bb. on JGs this bump is too big, so no matter how you set your hopup you get too much spin. This bump can be worn down with time (probably 10000 rounds or so) or you can replace it with a new one.
by spike February 26th, 2009Why a split washer rather than any other washer?
by Daniel March 1st, 2009Hey 6mm I noticed that you haven’t posted a mechbox monday in the past two weeks and I was wondering whats going on with that. I would love to see a P90 video come out soon. Any news on new videos would be much appreciated. Btw love the site, with the JLS SCAR videos came my infatuation with airsmithing and its from your videos that I have been able to maintain my own guns.
by Sam March 2nd, 2009Hey,
by R7 March 6th, 2009Instead of using washers, you can just use shims.
Oh yes, I had a problem with my m4 hop up. You see, when the element white h nub pushed down on my bucking, the bucking would be pushed down (obviously). However, the barrel slot that allows the bucking to be pushed down into the barrel for the hop up effect was TOO SMALL. The effect was the the h nub would be snagged by the small width of the barrel slot therefore disrupting bb flight. After a while, I figured out that the h nub was to wide for the barrel slot and thus was snagged onto the barrel making the other half of the h nub push on the bucking crooked. Anyhow, I shaved off some of the barrel to make a bigger area for the bucking to be pushed down through by the h- nub. It worked, and now, the H nub doesn’t get misaligned. I also decreased the width of the h nub which helped it squeeze through the slot on the barrel where the bucking gets pushed through.
In other words, if you are having trouble with the new H nub you put in your gun, LOOK DOWN THE BARREL. If you see the bucking protruding down the center of the barrel (as opposed to evenly spread out at the top of the barrel), the nub is misaligned and the mod neads to be done.
R7
hi there, i hv SR16 M4, everytime i shoot the 3 BB comes out not 1 by 1. what the problem? its hop up rubber or else. pls help
by btm_trie March 12th, 2009Another fix, that is easier for airsofters, instead of using a washer, stick a few gearbox shims in there. hear it works well.
by Daniel March 13th, 2009Most likely the timing is off, which will cause the BBs to come out 2-3 at a time. Sometimes the hopup can cause this, but 95% of the time it is the timing.
by 6mm March 13th, 2009bought a used G&P M4. worked for a bit then had a battery issue. after fixing that, it shot like crap…hop up issue I suspect. I nearly bought a new hop up unit. Glad I came across this post! I suspect this is the exact fix I need!
(hop up doesn’t seem to adjust, or is loose and won’t stay adjusted…)
by JoeX March 18th, 2009I have this problem with my AK how would you fix this?
by joe March 21st, 2009Tibor
The hopup has a moulding problem inside. go to this site.
http://shredderscs.proboards80.com/index.cgi?board=read&action=display&thread=18
by tmc March 26th, 2009can you all do a video showing how to remove the stock hop up a install a metal one peice hop up im trying to upgrade my aeg . whats funny is i can do my own gearbox work but i dont know how to change my hop up
by korey April 3rd, 2009Hey, I own an M4, i put a new D-Boys gearbox, hop unit and barrel in, plus a new 9v battery in a APEQ bow, which all came new, plus my motor which also works, but for some reason when i stick it all together it won’t work. I know all the parts work individually, but it wont work as a whole. the only clue i have to work with is that when i pull the trigger each time, i just hear the motor engage with the gearbox, but not actually rotate the gears.
by JaffaCake April 4th, 2009Whats happening?
Hey there, loose hop ups are really annoying Im thinking of changing my hop up I got a G&G M4 CQB-H and I wanna change my hop up part would this part I saw online would fit
http://www.airsoftpost.com/dboy-complete-metal-hopup-chamber-m4m16-series-airsoft-p-30826.html
it say it would fit G&G but I wanna make if this is all i need to buy because I’m gonna be buying online.
I also wanna ask because my m4 always shoots 12 oclock I adjusts everything i can move with the two sights but still the same thing. I also tested using .23g bb but still the same thing would changing the hop up piece can fix it?
by John April 5th, 2009Hi JaffaCake,
by R7 April 11th, 2009Make sure you did the following, and the gun should run again:
1- Is your motor in backwards? If it is, make it face the other direction. When it is in backwards, the motor has to fight against the antireversal latch.(this is VERY LIKELY to be your problem)
2- Is your battery fully charged (I’ve charged my Intellect 8.4v on the wrong setting a few times and ruined it).
3- Is your shimming job perfect with your gears spinning freely inside the case when closed/ tightened?
If all these are checked off, then I can say pretty confidently that there is no other logical solution other than having a defective motor or gears that aren’t the right torque level for such a strong spring.
R7
Hi Folks,
I recently received my DBoys Full Metal M4 CQBR. (3981M)
It is am amazing looking and feeling AEG! (And I am VERY happy with it.)
This is my first AEG, so despite a lot of research, please excuse any incorrect terminology etc.
Everything works 100% except, when I fire, whether in semi or full auto and regardless of hop up setting, roughly half of the rounds hit the target at 40 yards and the other half hit approx 20 – 25 inches lower.
While there is no pattern to which rounds hit higher or lower, the shots either hit at the “correct” height. ie: Where I am aiming, or they hit 20 – 25 inches lower.
What can be causing this? The “Y Axis”/Horizontal/left/right aim is 100%.
The variance between shots is only on the “Y”/Vertical
axis. (Ie: Shot are going higher and lower.)
What can be causing this and what should I try to correct this.
Please note that this is straight out of the box.
Fyi, I chrono’ed the AEG at 360 – 365 fps.
Any and all advice will be greatly appreciated.
Thanks,
by GI-Joe April 13th, 2009GI
i was wondering where can i get a guide on putting a M4 hop-up back togeather, specificly putting the tiny rubber bcuking in place, mine came out and i have no idea where it came from.
thanks in advance
~Mick~
by Mick April 20th, 2009Hi Gi- Joe!
by R7 April 20th, 2009OK, it looks like you have compression/ airleak problems. The way to fix these is to increase the airseal. For instance, wrap teflon tape around the cylinder head o ring. Then, make sure the O’ ring on your piston makes a good seal with the cylinder (you can purchase a #14 O’ring from Lowe’s for, like less than 2 bucks for an increased airseal). While you’re at it, check the seal between the air nozzle and the hop unit. Then, if you want to make sure that you fix the problem, make sure that the hop unit doesn’t leak air when in operation (which shouldn’t be too much of a problem). This all has to do with FPS consistency. If your FPS consistency drops, so does your accuracy. Let me explain- some shots drop lower than others because some bb’s are coming out of the barrel at lower velocities than other shots. So, when you fire, and the FPS goes up higher than the last shot, your bb will puncture the target higher than the lower velocity previous shot.
Also, make sure that the bb’s you are using are precision bb’s. Deviations in weight may make a little difference.
The gun’s bucking should be fine, but an upgrade to a systema one will make a difference in groupings.
There shouldn’t be anything else other than these issues that are causing your problems.
R7
Could you make a video to show how to replace a JG M36K hopup?
by Dave April 21st, 2009Does removing the screw on the hopup dial make it fall apart? I don’t want to attempt this and end up with a useless mass of metal and plastic parts that used to be a systema hop up.
by Caleb Morris May 10th, 2009Caleb, no just be careful when you remove the screw not to pull the dial off with it.
by 6mm May 13th, 2009Hello, Was wondering about the screws that tighten down on the inner barrel from the outer barrel. Most video’s I’ve seen shows people just sliding the inner barrel out without having to loosen these screws. Do people not really tighten them up? Thanks
by Renato May 22nd, 2009Hey Guys,
by alby May 26th, 2009I have a DBoys spr and my hop up unit is always a little engaged. I disassembled the hop up replaced the nub with a new one and still the hop up is engaged. By engaged I mean that when I reassemble the hop-up their is an obvious protrusion where the nub is located. My hop-up unit was all the way off when disassembled and reassembled. Long story short I can adjust the hop up for a down spin problem but not for an up-spin. Any ideas?
Alby
Hey, I have been wondering if I want to replace the body of my JG M4A1 with a metal Dboy receiver would I need to put in a “one piece hop-up” as I have been told I would by someone, and if so, could you do a video on how to do this or explain, and maybe show me where I could get one.
by streeetbob May 26th, 2009Sand around sides of the plastic nub under adjustment wheel, put back together using NO oil, sticky is better. I like the washer idea if I have one lying around.
by JT May 28th, 2009great guide…
thx
by fraggles June 3rd, 2009hey i had this problem i got my A&k m16 upgraded and it came back from airsoftgi and the bucking was not on correctly. My friend fixed it and it shoots great but i might be pushing 460-480 fps and .25s with no hop up still kind of goes up to much i was wondering if it was something wrong with the hop up maybe or just the tsd .25s im using. Im thinking maybe .28s or what? please help
by Charlie July 1st, 2009thx
hey i have a double eagle m4 a really cheap gun that i bought off ebay it broke 9 weeks after i had it thew gearbox stopped working can any1 help me fix it?
by zack July 28th, 2009I have a problem with my SR-25. The hop-up is adjustable, but when I turned it to the max, it barely lifted a 0,20 grams bb. For 0,25 for an example, hop-up is too low. Can i fix this myself somehow? Tried the silicon and barrel-cleaning already. Thanks
by SR-25 July 30th, 2009lost my hop assembly spring. replace it with a pen spring. fps drop by 50. cant find one for sale.
by tmc August 23rd, 2009Hey, since we are on the topic of M4 hop ups, how about the newer WA, WE, AGM and etc. GBBR hop ups? those are completely different from AEG hop ups and i can’t seem to find how to get mine out!
by Gaz September 4th, 2009Hi SR25,
by Vincent September 6th, 2009Make sure your hop up spring (under hop up arm) is in place. Also, don’t spray too much silicon oil in there because that may also be your problem. Or, one of your gears is stripped (on hop unit) and not working!
Vince
Hi all, i have a JG M4 S-System, which is an excellent buy might i add, but i have been having fps and accuracy consistency issues. I’ve just ordered new H-hop and bucking to fit in but wondered about an all metal hop. Obviously the the all in one construction is very different to the standard hop unit which is separate from the BB feed tube. (sorry if the terminology is wrong)
by steve September 10th, 2009Would i need to do any mods to the body to get one in or is it a simple swap out.
Cheers
Steve
Steve,if you do get a full metal hop up (one piece) then yes you will need to modify your body, the only way you wouldn’t have to is if you got a metal body, which in that case you need a metal hop up or it wont work. hope i helped. P.S. just look up how to modify your plastic body so a metal hop up will fit, all you need is a dremmeling tool or anything that will cut through plastic
by Drew September 14th, 2009Streeetbob,yes you will need a one piece metal hop up, i would suggest a Prometheus or a systema . you can get either of these at airsoftgi, evike or redwolfairsoft.com
by Drew September 14th, 2009Alby,do you have the spring under the adjustment arm? if not then it will always be pushing down on the nub therefore you cannot adjust for less down spin.
by Drew September 14th, 2009Cool; I’ll have to tell my friend because his M4 hopup is awful. Can you do one on the A&K M249 hopup, and while you’re at it the gear box? Thank you!
by Otto September 22nd, 2009the g36k hopup should be the same as the g36c i still had some problems with it although the nubs that keep it towards the barrel broke and had to get another so whoever has a g36 i strongly recomend a metal hop up (bought mine from SRC) and a systema bucking
by Ruebn September 26th, 2009i have jghk416. i wnt to put it on it’s high end, change the spring into the max… i just want to know what other parts needs to be change so that my plan will materialize. it will be much apprieciated if it will be itemized and specificied what are needed. hope somebody can attend to my call….thank you
by spike September 28th, 2009Hey all, I have a JG M4 carbine, I just replaced my plastic 2 piece hopup with an all metal hopup. I had to completely take the gun apart to get it in there but it all fit back together like magic. But the dang thing doesn’t work now. I pull the trigger and the motor engages and it sounds like the mechbox and piston run through their cycle. But no BBs come out the business end. I know BBs are feeding into the hop up, I cleaned and checked the barrel for jams. But still nothing, BBs will occasionally roll out of the barrel. I did lube the whole works up pretty well, maybe some got in side the bucking, would the BBs be sticking to it now? Some kind of massive air leak? Be glad for any help, thanks
by TJ November 18th, 2009Probably a broken air nozzle? Maybe a dis-alignment of the hop up chamber relative to the nozzle?
by R7 December 15th, 2009R7
oit of the box i found a defect problem with my new m4. the charging mechanism wont rturn back when i charged it.. seems a loose spring or without the spring mechanism to activate a charg. also the noosle of the gun were not align. need a help fix. thnks
by saile reye December 23rd, 2009okngarud29@yahoo.com