ICS L85 has low and inconsistent FPS

[british rifleman]

Got an ICS L85 middle of January and it fails to have any fps on the first few shots after not firing for over a minute (they just dribble out and reach about 2.5m in front of me) before they pick up. Last time i chronoed it on .20 bb's it reached a grand total of 70 fps. any advice or help?

 

[richmt11]

Have you checked your hop? Try it with the hop wound right off and if it’s the same, have you had the hope assembly apart at all? Perhaps it’s gone back together wrong or something?

i don’t know ICS L85 but that’s pretty much a first check for me when people have their guns dribbling bbs rather than shooting them!

 

[Prisce]

If it’s not the hop causing the problem, it sounds like the nozzle could be leaking air too, had this same issue on one of my guns recently. Hop unit didn’t have a nub in, and the o ring on the nozzle was damaged. After fixing both it works flawlessly.(check the hop unit first)

If your not confident fixing these yourself,(the nozzle does require opening up the box) a good tech shouldn’t take too long to fix this.

It definitely sounds like an air leak, so do a compression test first(YouTube is your friend) before you start taking it apart.

 

[Chris_B]

70 fps is catastrophically low... I'm pretty sure it's a massive cylinder air leak.

Is the L85 new or 2nd hand when you got it?

The piston O-ring needs changing periodically as it's a consumable part that wears, same goes for the cylinder head, that has an O-ring too, they both should be soft and pliable, if they're stiff, they won't have an effect on sealing.

The inside of the cylinder should be smooth and polished, hold it up to the light and check for score marks. 

A light smear of silicone grease is needed for the cylinder & O-Rings.

Cylinder head O-Rings are hard to find, but I think it's something like a 1mm x 20mm size, but a few wraps of PTFE plumbers tape over the current one will do the trick. 

As for piston O-Rings, you can pick up a pack of 5 for like £5 off eBay.

I'd start with those, then look at the nozzle & hop rubber/ unit.

 

[british rifleman]

i took it in to my local store and they had it firing at 350 ish on .2 straight away, went to use it this weekend and it chronoed on .25 at 150fps its doing my head in could it be my mags springs are overfeeding and putting too much force on the bb,s 

i got it brand new in january

 

[Chris_B]

If your local airsoft store got it firing at 350 straight away, then you take it to a game and it isn't working as when it left the store, take it back.

I take it you paid them to fix the issue?

0.25g should chrono at 300-315fps

As with mag follower spring... Load a single BB into the chamber and fire it, see what it chrono's at (I'm assuming you have a chronograph)

 

[british rifleman]

im taking it back later this week, its still under warranty and i know the staff there quite well through my uni (they wont fuck me over) my chrono is turning up later this week but its chronoed low every time its been used and thats on at least three different chronos. i use a 9.6 battery with nuprol 30-140 rd midcap/lowcap mags but they are less than a month old so they may just need bedding in.

it also missfeeds the first round fired so nothing fires on the first trigger pull and two come out on the second trigger pull

they said it was the hop that was causing the fps problem which is a stupid problem that i should have known to check for but i didnt touch it after they gave it back to me, so i think there is more to this problem than just the hop

 

[british rifleman]

edit:

i used my new chrono today and got an avarage of around 202fps on .25s out of an ics hi cap that came with the gun, and 235 fps with .2s  its going back to the shop tomorrow as i have some other stuff i need to pick up

 

[british rifleman]

found out that the hopup was turning itself on over time it now chronos about 305 on .2 bbs

 

[Adolf Hamster]

you sure it's not mags being too tight?

my m4 has a nasty habit of dropping to about 100fps for the first few shots before picking up again once you've drained the mag a little. i really ought to make something to de-load the mag by just the right amount.

i suspect it's the bb's having too much pressure so the tappet plate spring isn't gutsy enough to push the bb into the chamber, mainbly because on the same mags the f2000 doesn't have that problem and it has a much stronger tappet plate setup.

 

[british rifleman]

its not the mags, the hop up unit turns itself on over short periods of time, it did it noticeably in less than 24 hours. i might just replace the hop unit as it gets annoying having to redo my hop each and every game

i know its not the mags as fully loaded i have no inconsistency or when they are half empty ive put 40 rounds 1 after the other at 2 second intervals through my chrono and got a fluxuation of about 10 fps around the 310 mark

 

[Chris_B]

Silly question, but have you checked your air nozzle & tappet plate? Not familiar with the ICS L85 (I own the Ares version) but can you see the air nozzle reciprocating in & out of the hop chamber when you dry fire (I know dry firing is bad for the AEG btw).

And are you able to push the nozzle back into the gearbox and does it return under its spring tension? (The nozzle has to be in it's forward firing position, i.e. piston released).

C.

 

[british rifleman]

the final problem has been identified. when the hop up unit was assembled initially by the factory the rubber was coated in silicone oil. this is the cause of all the problems I've been having it has been resolved by simply dry wiping away all the excess oil and reassembly of the hop up unit. if its not something that is known to commonly cause the fps drop in an airsoft gun you're unlikely to check it which is why it went unidentified for so long. when the gun first got ordered in i picked it up before the store could do there initial look over of the gun just because i went to pick something up when it first came in and got it on the day so my local store hadnt checked the gun before i picked it up.

 

[Chris_B]

Glad you got it sorted, it's always the simplest of things, but that's how you learn I guess.