ics m4, fps decrease and strange noise?

[joshh1512]

Ok, so i have an ics m4, had it for about 5months now and it's running decent, just needs a tighter barrel and new rubber, but chrono'd it today, and it's 250fps on average? Now not sure if the chrono was a dodgey one, so i will try in on mine at home, when i find my cleaning rod to un-jam it, doh!

Also, occasionally it makes a strange noise, it's hard to describe, if i must i will upload a you tube video, but basically it sounds like either the motor is rattling about in the grip, or it's when the gears are slowing down to a stopped position. Could it be anything to do with the anti-reversal latch? But surely, this should have no affect on the fps? Could this problem be damaging my gun, say if the AR-latch has gone, will it cause damage?

By the way, i rear-wired my gun a couple of days ago, could this be a factor?

Please, help would be nice as i am getting worried!

[johnnyj]

Re: ics m4, fps decrease and strange noise?

hmm did you remove the AR latch ? ( cant see you doing that on a ics but have to ask ) but could be bad shimming or the gear's winding back if the ar spring is damaged or missing
as for the low fps could be the chronoand did you test it with hop on ?

[SAS Scott]

Re: ics m4, fps decrease and strange noise?

This happened to my friends ics and it ended up being something to do with the safety lever or ar latch (sorry I forget) and we just tapped this bit down and it stop noise but with fps I have no idea ,maybe a bad seal.

[Silentsniper]

Re: ics m4, fps decrease and strange noise?

Would recomend that you swap out the spring for another one for the FPS decrease. Also the problem might be your motor alignment, Look at the bottom of your grip and see that big screw in the middle of the grip? Turn it half a turn clockwise and fire the weapon this will adjust your motor height within the grip and ensure that your motor pinion is connecting to the bevel gear correctly. Keep turning it half a turn clockwise untill the sound has gone. If you go to far and the motor grinds with the bevel gear just simply turn it anti-clockwise.

[joshh1512]

Re: ics m4, fps decrease and strange noise?

Right, i will try the motor height, the AR latch should be fine if not, i may get a new one, any recommendations?

As for the shimming, i have a feeling this may well be the problem, i didn't particularly know the shims were a big factor in the gbox, guess i should of just looked this up, anyway all i did was leave them were they were, think one fell of so i simply put it on the gear and fit it back together, now is this wrong to have done that? Do shims need to be perfect? If it is them, do i need to buy more, or will the ones have be enough? If i completely re-shim it, what benefits will this give me? And how hard is it, any good guides anyone can recommend?

When i put the ar latch back in, the spring was defo there, will open her up if i dont get it sorted by adjusting motor height...

[Silentsniper]

Re: ics m4, fps decrease and strange noise?

Benifits of having a perfectly shimmed gearbox are that it will make the gearbox run alot smoother. May well be the shimming aswell. As long as you have a few extra shims you'll not need to buy any more. It's relatively simple to shim gears mate. Just open up the gearbox and remove the tappet plate, cylinder, cylinder head, spring, spring guide, piston and piston head and the air nozzle. I also like to remove the anti reversal latch when shimming. When they're all removed put the other half of your gearbox shell back on the other half, now turn the sector gear and make sure the gears are turning smoothly without any resistance. Now check the gears for wobble. If any wobble is occuring when put a shim on where this is happening and retest. when you can no longer feel any wobble then your gears are shimmed perfectly.

[joshh1512]

Re: ics m4, fps decrease and strange noise?

Well i don't have any spare shims, might be an idea to get some when upgrading my upper gearbox (my gbox is split by the way, which makes it soooo much easier to get to lower gearbox) What size shims do i need? And it sounds slightly easier than i thought, will check around some guides. In the mean time, could you give me some advice on what upgrades will be good for my upper gbox? Looking to hit the exact 350fps mark, with good consistency, and better range, is this possible with gbox parts, or is that all down to the barrel/rubber/hop? And what spring would i be looking at for 350fps give or take 5? An m110? Cheers

[Silentsniper]

Re: ics m4, fps decrease and strange noise?

Extra range is all up to the hop up/barrel as you said mate. An M110 should give you about 340-360 depending on the brand.

[johnnyj]

Re: ics m4, fps decrease and strange noise?

have a look on youtube there are some simple shimming guides on there , its very easy to see if the AR is in there as there should be a small lever at the top of the open GB if its spring loaded its working

as for the spring at most i would say m100 and even then with a good airseal it will still be over 350 fps

[Gunslinger]

Re: ics m4, fps decrease and strange noise?

mine had the same issue it was the anti reversal latch it would cause a double feed or missfire on semi auto if you need a new a latch you can get one from z1 and you need the ics one coz it works with the forward assist