M4 firing problems

[Tiercel]

Re: M4 firing problems

Ok so! One problem solved - another problem developed!

You were right, it turns out the hop unit was too close!

ProWin and Madbull combo now works. Ive taken the overbarrel spring off and using the grub screw combined with the spring from a biro clicky pen over the top of that! :P The ProWin now fires happily!

What I noticed when I had the two hop units next to each other MSPaint diagram to the rescue!



Now my M4 is front wired, so the wiring is supposed to run around the hop unit feed tube and into a tiny slot to go into the fore grip. BUT with the ProWin having a big chunky flat bit where the nice round bit is supposed to be, the wiring crammed against the hop unit and outer barrel which left no wiggle room whatsoever and jammed the ProWin up against the gearbox causing all these problems!

Currently Ive got the wiring hanging out the ejection port/dust cover which obviously isnt a practical long term solution. So now it looks like if I want to use the ProWin Ill have to rear-wire the M4. Which isnt necessarily a problem as I hate the stupid tiny hole you have to thread the wiring through to front wire it, but it does mean getting a new stock and the hassle of rewiring it.

Also the ProWin is currently performing terribly, the BBs start to drop off after about 10 meters, either that or 1 in every 10 or so shots will have 9000% hop power and spin off up into the sky.

So now I need to figure out why the ProWin isnt working like it should...

[Sitting Duck]

Re: M4 firing problems

The nozzle entry on the hop unit....
you can place an o-ring or washer on it to push the hop forward as a temp/bodge/test
problem is washers and even rubber/neoprene washers are a min of 0.8/1.0mm thick - too much no doubt
you might be able to place tape or make up a very thin piece of card or something to just fit over the nozzle port of hop
then this will push hop forward allowing bb to slip past nozzle and chamber......

This is just a temp fix or test but if fps doesn't drop then nozzle could filed a smidge if really needed
or
use another hop as different hops work well/crap - bet prowin in another gun will work flawlessly as is
It all comes back to the tappet "window" as I call it plus ensuring the window is 8mm or more

Yes there are ways you can increase window size
eg: filing the front of tappet plate and then perhaps nozzle a smidge
plus when assembling stuff there are soooooooooooooo many variables that throw the mix out like I mentioned

I like shs tappets atm, but often the nozzle lug is a little back off center - no problem coz if we sand front of tappet the lug will be nigh on centered
but also using a SHS red nozzle @ 21.45mm the rear of nozzle shows a little proud of tappet at back
it might mean the nozzle hits the cylinder head but not tappet plate so impedes possible retraction by say 0.2mm
Also the shs tappet seems to retract a little further than other tappets - but be careful it doesn't "bottom out" and risk bending or even snapping if it hit home against cylinder head after using a delay clip for example - ohh joy the fun n games.....

Now when you get the tappet bottoming out on cylinder head there isn't much you can do, you could sand the fin but you are in effecting losing any possible further retraction you might have at your disposal

I have been messing with some recent boxes and making the tappet retract as much as possible but modding to use the possible extra retraction:

http://www.airsoft-forums.co.uk/inde...te-travel-mod/

mods excuse if link not allowed but been messing with stuff and got total tappet travel increase to nearly 9.5mm or enough to fit an old 8mm bushing (9.5mm aprox outer diameter on flange)
So the nozzle is getting retracted way more that bb's do seem to feed better
you have to check fin at back don't hit spur gear shaft and a bit of work elongating the holes on cylinder head plus file cylinder etc...

But feel companies could make cylinder heads set say 1mm further back or add on 1mm extra on front of head instead of gluing on extra material to then allow just a small file of cylinder and viola nozzle can move backwards to where red/blue marks are
There is a little more checking to ensure the whole tappet moves back and fin doesn't hit spur or rear runner of box or part of tappet doesn't touch teeth on sector gear but nothing major as box is assembled

Still early days but think the tappet travel could easily be increased or improved to provide 9mm not 8mm aprox travel for better feeding
Please note retraction is not the only thing for perfect high speed feeding - there is also the duration the tappet is held at furthest point too
so a good delayer is needed still to expand the time the tappet is held fully back

Yes DSG's can't use delay clips but this tappet mod may also help DSG's to feed by extending the travel a smidge for the very brief time the nozzle is retracted on higher speed hose machines
Well actually DSG's can use a tiny tiny delayer a tiny piece of capillary pipe 3mm internal & 5mm max outer diameter expoy glued on but paying very close attention that the extra 1mm wall of pipe doesn't rub too much on underside of tappet plate - but still can offer a further 1mm retraction from 1mm wall of pipe
might need to be 0.5mm wall (3mm ID & 4mm OD pipe but you get my drift for DSG tappet mods)

Phew - I gotta stop messing with boxes too much and get out more but have been looking at all sorts of headache problems and really wonder lots of times wtf they still churn out so many parts with crap tolerances that often need modding or tweaking to get working
yes parts/boxes/guns really do vary in TM compatible tolerances but jeez they "could" make some parts with a bit more give or heck even SHS or Lonex make some parts for "TUNING" - these tuning parts would have a bit more on them for techs to "fine tune" or file a wafer off here n there to operate precisely in each individual gun they build
Rather than start pi$$balling about adding bits n bobs to get tolerances more exact

Oh well modding rant over - try a thin circular washer/spacer/card on picky hops is my original suggestion for feed or picky hops
(after checking bucking seals on hop/box and bucking lips aren't too tight/bent to not allow bb's to manually pass through - plus possible mag tape)
Yes I know OP did these tests so we know nozzle isn't clearing on pro-win but ok on normal hop unit
But repeating this in case others just steam in and stuff without performing very important basic checks first - not wise

As for hop & bb's going sky high then 10ft next shot....
The bucking could be contaminated with grease n crap - well no coz that is inside you might think
but still could of got crap inside when removing/refitting from hops or trying different barrels

So it might be wise when stripping hop, take bucking and check for possible signs of wear/spilts
then simply get some WARM not hot, soapy water with lots of suds/bubbles in
bit of fairy washing up liquid in a cup with nice fluffy bubbles - WARM water not hot, give it a quick wash to degrease and clean and crud off
refit nice dry and degreased bucking which will provide more grip for our old friend mr magnus

There are other things to check but I wash any bucking I reuse or hop rebuild is what I'm saying just in case any crud in there
Hope some of this anybody with poxy lame ar$e gun feeding hopping problems & nozzle headaches

Meantime - I really need to stop analyzing gearboxes and hops way too much and get out there to shoot or just get out more in general I think

[Tiercel]

Re: M4 firing problems

Back to square one ProWin has stopped working again. Identical symptoms as before...

I got some metal washers and dremeled them wide enough to fit around the ProWin nozzle tube bit, no joy. Dont know the dimension, though eyeballing it agaisnt a ruler looks like its almost exactly 1mm. Perhaps a rubber O-ring would be better fit as it has more squish-factor and can adapt to the needed dimension, but I dont have any to hand to try. Going to try making some out of a few sheets of thin cardboard so Ive got more fiddle-room to add or remove thin layers of card

What I have noticed is that depending on the mag, the position of the hop unit moves. If I have the hop totally wedged forward with 0 movement, the mag wont fit, so it NEEDS to be back about 0.5-1mm or so to allow mags to feed but the we seem to be having the hop unit is too far back and not clearing the nozzle problem. If you rock the mag back & forth ever so slightly in the mag well, you can see the hop unit moving in the ejection port. Im not sure if its meant to be moving or not?

[Sitting Duck]

Re: M4 firing problems

Simply put for less grief.....

You might just have reside pro-win might not work in ya M4
unless you like major ball aches

What concerns me is exactly WHY it worked then started the feed trouble...
Going back to sniperjesus and worn tappet plate of the fin
this could have started to wear quickly if nozzle was hitting the cylinder head and restricting it going further back and thus stress/wear on fin takes place
or can bend/snap if really bottoming out - but the fact remains if tappet/nozzle hits the head with delayer trying to pull the tappet further then wear or crap will happen

So this may then drop say the 8mm tappet window down to 7.5mm and you got very fine ultra tolerance or window and then some picky hop/nozzle combo's equates to crap seal/fps or feeds next to sweet FA - even on semi
(normally if mags and/or window is getting picky guns can often fire on semi ok but really good reliable fast feeding on full auto is not so straight forward to obtain)

For now you might want to just try and use the gun with a "conventional" type hop and at least get out there and use it for a few weeks say
If then the tappets wears more and it all goes pear shape then you may have to look at opening her back up AGAIN !!!

Damn I really feel ya pain & frustration....

Clean up the bucking in old hop, try and see if you can get the clips or missing bits n bobs to get it all working and just try to use her for now
See how she goes and like I said if she goes crap again then maybe look at different delay and/or tappet mods but that is more work and more headaches

I'm no guru walk on water mofo techy expert but just posting some of my findings and stuff I have tried or started to use with poxy picky gun problems

If you need a bucking or some bits to try just gimme a shout

[Tiercel]

Re: M4 firing problems

Giving up isnt my style, but this is quickly turning out to be more hassle than its worth

For the life of me I cant get the hop to work again... Ive tried everything that made it work last time but its having none of it. Ive measured the nozzle travel, its exactly 8mm with no hop attached, but for some reason its just not clearing the hop, not pushing the BB in far enough and causing it to jam...

Maybe a new rubber and H nub in the old hop will yield better results, Im not keen on trying flat/R hopping because that looks too permanent and easy to cock up

[Sitting Duck]

Re: M4 firing problems

Flat hop isn't that hard - even if you mod an old bucking
prommy nubs - can get 2 x blue/black for say £13 in UK
(google coz can't link other places)

either flat or bridged types or wtf get 1 of each = 4 nubs

then just mess about with some old buckings to trim up at first
once you happy then maybe a decent new bucking like guarder/systema etc...
want a 70 perhaps than a 60 bucking

or get a flat hop bucking with no nub but plenty make all their own nubs and mod conventional buckings

tbh - this you can mess with later - get gun to work maybe - just shooting stuff then once done mess with bucking bits n bobs
a gun that shoots and you can improve accuracy on is better than a gun that just won't feed

and you thought getting that gearbox all closed up shimmed well and running sweet was the end of all headaches
AAAArrrrrrrghhhhhhh - gun no feed - I hate toy guns - hate them hate them hate them

[Tiercel]

Re: M4 firing problems

I never really understood the different types of bucking available! Back in my day when I first started all this modding malarkey there was one type of hop available, the one your gun came with! different degrees and types of nub and bucking are all a bit confusing.

[Sitting Duck]

Re: M4 firing problems

it isn't so much the bucking but the the nubs or how the pressure is applied
(yes bucking matters but basically we are talking about the difference in applied pressure to the usual 3 types of hop)
a good bucking G&G Green, Maple Leaf + others can work quite well but there are lots of factors just like inside the box that can make it perform less than great
nubs can help H nubs can help ensure bb is centered but some can be sharp that it can cut or wear bucking

after this you got flat hop which is an improvement over conventional imho and others will say
though may I stress a GOOD conventional setup will work just as good and maybe better than a poorly fitted Flat Hop
though like for like the Flat hop is better, how much depends on what old system was like prior to trying Flat Hop
Some stock barrels have been so damn sweet that aftermarket TBB's are not needed at all
and some TBB's have been finished and crowned real $hite that either are useless or will probably end up like a stock or wide bore after you lapp the hell out them
barrels - some have a decent size window area for flat nubs or R-Hopping and others you think wtf and how am I gonna get a tiny conventional nub in there
plus hop arm and window lining up badly - ohh yeah is there any bit on a gun that is just straight forward
(maybe filling mags with bb's but most other stuff all sorts of crap n problems can give us headache after headache)

then R-Hop which is a little more work and an area I need to look into myself soon

[Tiercel]

Re: M4 firing problems

Guess what?

Now the original hop unit doesnt work ARGH.

I have no fecking clue whats going on anymore or why things arent working. Anyone wanna buy an M4 before I just smash it into a million bits?

[Sitting Duck]

Re: M4 firing problems

Jeeeeez you are having ultra $hit luck now......
(kinda doing my head in and it ain't my gun ffs)
if nowt is working then back to basics I guess and rip the box open

maybe a shs tappet and consider modding for tappet travel increase - though to elongate the head's holes is a lot easier to do on a decent plastic cylinder head
add delayer - believe it or not a copper round one by default has about 0.25mm more travel on it than say other types
though the round copper delayer doesn't hold tappet fully back as long but a slightly increase on retraction
working very well on 27 & 32rps guns atm

This would give you 9 to 9.5mm tappet retraction if sanded front of tappet plate - gotta be plenty
then a golf ball should feed into hop - ok maybe not but you get idea....

Have a think and lmk if you need owt

[Tiercel]

Re: M4 firing problems

the G&P gearset Im using has a delayer fitted on the selector gear as standard, looks like Ill be ordering a new tappet plate too then. Argh.

I might have to put the M4 on the back burner for a while then, until I get a new tapped plate and a crane stock sorted. If Im gonna open it up again I may as well rear wire it whilst Im in there. Plus that might help with the wiring jamming up the hop unit.

To be continued I suppose...?

[Sitting Duck]

Re: M4 firing problems

like I say if you need owt gis a shout
or
cut your losses sell gun
or
give it to Simon at TWA think he maintains the guns n stuff
but think you wanna now sort this as its now a battle and got very personal

feel ya pain sir
ps +1000 for Dr Cox - my hero/role model

[Tiercel]

Re: M4 firing problems

Im not selling it, mostly because its not working and not worth anything! :P

Ive got the old hop unit working again, but with a caveat - it only works if you hold the magazine in place and pivot it slightly forwards, which if you look through the ejector port shifts the hop forward about 0.25mm so it seems we're back to the "hop sitting too far back" issue... I cant find anything thats thin enough, but also firm enough to hold the hop unit in place without pushing it too far forwards.

Either way, its currently in a semi-working state and Ive had enough of it for today! Ive put it back together and leaving it alone until Ive got a new tappet plate and stock sorted out. Then Ill strip it all down and start all over again... and probably cause myself some more headache!

[Sitting Duck]

Re: M4 firing problems

might be worth googling up the std length of nozzle used
it can vary and G&P might use the slightly shorter M4 nozzle of say 21.2mm than longer 21.5mm

there's loads of stuff that can throw it all out and shs red nozzle is sometimes a smidge too long for some builds
found there fine for G&G's but some new guns/hops the nozzle can be a tiny too snug fit sliding nozzle into hop

Damn poxy guns - when people think chucking in a load of "go-faster" parts in a box is so easy
they often find out the hard way like we all have it really is not so simple as that

http://www.riftairsoft.com/showthrea...ot-feeding-BBs

not saying you are using shs red nozzle but just an example of some other poor sod's luck
but you can take comfort that when you finally sus the bastid you will have a much better understanding of how critical it can be
plus a much more detailed understanding of it all

then try a hairline trigger mod - now that is another frustrating critical tolerance area of fun mod
all on top of getting shimming so nigh on perfect that gears and/or motor's don't wear out very quickly from strain
yes we all take our time but some builds are just nothing from a painful ball ache from start to finish....
I don't think to this day I have been truely 101% perfectly happy with any box so far but I'm always finding fault with anything even stuff that does work well
but will say after problem after problem I'm getting better though the builds seem to taking longer as I can't believe you have to check EVERYTHING in such detail

[Sitting Duck]

Re: M4 firing problems

here is an example of how nozzles can vary on M4's M16's like I said previously
just like AK long/short nozzles

link to other site but US and this place has loads of info on nozzles - anyway:

http://www.clandestineairsoft.com/no...e-b-p-129.html

http://www.clandestineairsoft.com/no...e-a-p-137.html

http://www.clandestineairsoft.com/no...50mm-p-25.html