FPS very poor on my JG G36

Kashkai

I bought this gun as a back up/loaner gun. However while it's 2nd hand, it's in showroom condition externally. What's on the inside is evidently not! I chrono'd it yesterday and the best it could do was 260fps. I plan on putting a 6.03tbb and a new hop up rubber into it to see if this helps. Should I look at anything else like the motor before I go exploring the gearbox???

thermo

How old is it? Maybe the o ring on the piston is dried up/worn. Have you cleaned the barrel? I once saw a gun go from 275-320 with just a good cleaning of the inner barrel.

Kashkai

I was told it was just 6 months old and it is in excellent condition but I might pick up a replacement o ring anyway in hobby tomorrow. I should have cleaned the barrel yesterday when I had the gun apart (bit more difficult taking this gun down compared to my M4!). However, as I planned on replacing the barrel and hop up rubber anyways, I didn't bother as this barrel will be discarded in favour of a Madbull 6.03. These Madbull barrels have always given me big improvements in fps and accuracy in the past (sometimes too good as my Raider is now chronoing at 327,328 and unfortunately sometimes 329! Guess I'll have to either snip it's spring or put the stock barrel back in).

T4RGET

Kashkai wrote: »

I bought this gun as a back up/loaner gun. However while it's 2nd hand, it's in showroom condition externally. What's on the inside is evidently not! I chrono'd it yesterday and the best it could do was 260fps. I plan on putting a 6.03tbb and a new hop up rubber into it to see if this helps. Should I look at anything else like the motor before I go exploring the gearbox???

I definitely wouldn't bother looking at the motor for a problem in FPS anyways.
Like thermo said just clean it and see what it does. It's probably just an air leak. turn the AEG upside and place a piece of paper over the magwell and fire it (no BB's) and see if the paper moves. If it moves a lot it means there is air leaking from the hop up unit. Secondly if you do manage to open it up again check the air seal between the air nozzle/cylinder head and piston. Hold the cylinder with the cylinder head in your palm and cover the head with your thumb (where the air nozzle goes) then push the piston into the cylinder as fast as you can. If the piston just slides in to the cylinder the problems lies with either a compatibility issue or ware and tear. If the piston is really dificult or impossible to push into the cylinder the problem lies somewhere else. I'd also check the gearbox for cracks and to see if the spring was cut.

Kashkai wrote: »

I was told it was just 6 months old and it is in excellent condition but I might pick up a replacement o ring anyway in hobby tomorrow. I should have cleaned the barrel yesterday when I had the gun apart (bit more difficult taking this gun down compared to my M4!). However, as I planned on replacing the barrel and hop up rubber anyways, I didn't bother as this barrel will be discarded in favour of a Madbull 6.03. These Madbull barrels have always given me big improvements in fps and accuracy in the past (sometimes too good as my Raider is now chronoing at 327,328 and unfortunately sometimes 329! Guess I'll have to either snip it's spring or put the stock barrel back in).

On the side note of your M4, i use an M85 spring, G&G green and 6.03mm madbull barrel and get 322 every single time, it can vary every 10th shot but variations are little.
Clean the barrel of the G36 when it's assembled, it's not as effective but it will give you an idea. just turn off the hop up use some damp cloth and clean the barrel a few times, then go through it again with a dry cloth

Hope any of that helps

Kashkai

Just an update on my problematic G36. Turns out it was a drilled cylinder causing the lousy fps. New cylinder install, and with the tbb and new hop up it's now shooting at 324fps.