Poor FPS - Airseal?

[dfrear]

Re: Poor FPS - Airseal?

Just as a note, this is a proline box - not sport

[JOE90]

Re: Poor FPS - Airseal?

ahh well, maybe not the same issue but seems strange dont you think? Ill still let you know how i get on just in case

[JOE90]

Re: Poor FPS - Airseal?

and just to clarify, an sp90 would be putting out around 280-300fps in a standard setup, not 330 as you seem to suggest, thus making your issue sound more and more like my cousins

[Gaffa]

Re: Poor FPS - Airseal?

(Well it is a Guarder spring, which have been reported to be quite a bit more powerful).

[KaRcop]

You may as well replace the hop rubber - it's cheap and easy and may help the air seal problem. That or at least take it out and wash it out then re-fit it. Does the air nozzle look intact?

[dfrear]

Re: Poor FPS - Airseal?

Air nozzle looks fine as far as I can tell, I do have a metal one from a G&P gearbox that I may try out. The SP90 most certainly put out about 330fps in the previous gearbox.

[North West Outpost]

Re: Poor FPS - Airseal?

Some springs are quoted using 0.25's not 0.2's.

Don't talk about bent cylinder head nozzles.! Feckin things...Just don't.

Believe me they can look fine and dandy...You can also dissapear up your own ar5e trying to find out whats up with the gun everything looks just as it should. Muchus head scratching do loads of stuff to no avail.

So yeah it could be a bent nozzle.....

[Shinotama]

Re: Poor FPS - Airseal?

A stripped piston can't really be the reason for a low fps, or a decreased fps.

The only way a stripped piston can be a cause is if the front (piston head end) teeth have stripped, meaning the piston will return forward before its full cycle. If this is the case, the gun shouldn't really work, or be used, as the sector gears teeth would be effected, and damaged.

If a piston is going to strip, it's going to strip:- normally as a result of poor shimming, or incorrect AOE.

It's not CA gearboxes at all. I've worked on many. Ask yourself how a physical gearbox is different to any other? There isn't any. One may be more reinforced, but certainly doesn't mean its going to produce poor fps. The components inside matter (and I've always found CA stock internals to be good) - however, what I have found is that the stock CA hop unit, rubber and nub aren't great. Well, the latter is fine, because a nub is a nub to me (this one is the right stiffness).

Yes this is a quote from far up I know..

The teeth had shredded off it so it was not pulling back far enough and screwing up just like you said too, thats what I meant =)

[Bachelarius]

Re: Poor FPS - Airseal?

Little tip I learned recently for nozzle to hop leaks. Chamber a bb and remove magazine. Loosely stuff a ball of tissue in the feed pipe. Fire. If the tissue falls out, you have an air nozzle to hop issue. If the air nozzle flies out, you have a major air nozzle to hop leak.

Edit: meant tissue, though the above statement still stands, haha.

[dfrear]

Re: Poor FPS - Airseal?

Right, finally got around to this. Found that the piston appeared to have a pretty bad airseal. Sorted that by changing the "surround" (damned if i know what its called) and replaced the nozzle with a metal one.

Unfortunately, that didnt seem to make much difference (don't have a chrono but compared to the "feel" of another gun dry firing). Changed the hop unit too, about the same again.

Bit stuck :\

[JOE90]

Re: Poor FPS - Airseal?

As I said before mate, I think its the classic army piston, change out the piston for a new one with a bearing piston head and I garuntee you your fps will up itself, I've had the same issues with classic army boxes.

[dfrear]

Re: Poor FPS - Airseal?

Ah sorry Joe, I missed that one I'll pop the piston out and try another, got a few knocking about anyway!