Hopup Compression Loss

[ThunderCactus]

oh rry?
Then I can attest that prometheus and G&P springs don't lose power

[CDN_Stalker]

Ya, that's the first time I saw it happen that made an impact, remember chronying it a month of so later and saw it had dropped to about 285fps..... and this was always after cycling in semi end of game day. But was also the only time I used a Modify 90, the other springs I had previous were Modify 100s and were fine. Plus using various other springs, and installing all kinds of springs into dozens of guns in my tech days, never heard anyone complain of spring power loss, just that one fucking Modify 90! Lol

[ThunderCactus]

And that is why we should all stay away from modify. lol

[audi_bhoy]

^^ +1 :P Had bad experiences with those springs, they were the worst over my compression tests...

[Maethori]

Originally Posted by CDN_Stalker

Ya, that's the first time I saw it happen that made an impact, remember chronying it a month of so later and saw it had dropped to about 285fps..... and this was always after cycling in semi end of game day. But was also the only time I used a Modify 90, the other springs I had previous were Modify 100s and were fine. Plus using various other springs, and installing all kinds of springs into dozens of guns in my tech days, never heard anyone complain of spring power loss, just that one fucking Modify 90! Lol

I also had a Modify S120 that started at 425fps consistently and is now down to 390 consistently. Similarly a Modify S110 in a different gun started at 430fps and went down to 410fps.

[kyemoney1016]

Regardless of what KA put in there, you need a ported cylinder in there for that barrel length period, breaking point where a full cylinder can work is about over 400mm I recall (somehow 470mm sits in my mind). With that length barrel and a full cylinder, you are already 30fps lower than a ported one would give you.


That statement is wrong. Actually it doesn't matter. Dont waste your money on a new cylinder. A port will give you less air, less fps. If it has a non-ported cylinder that is fine, especially if you put in a shorter barrel. Non ported is good for barrels up to like 400mm or something so if you put in a 300mm you are definitely fine. Sounds like your just loosing air between the air nozzle and hop-up chamber.

[lurkingknight]

bumping a year old thread?

Anyway, to somewhat debunk your advice while not entirely wrong, it's not entirely accurate (or complete)...

There's truth in properly matching air volume of your cylinder to your barrel in a ratio, while it may not have an effect on fps with one BB weight, overvoluming like you are suggesting creates higher than expected muzzle energy when using higher weight BBs on the same setup. In perfect lab conditions, you would expect muzzle energy of a .2 with X spring to be the same as a .3 with the same spring, minus the difference in velocity. When you fuck with the cylinder to barrel air ratio, the projected outcome starts to change. Overvoluming can net you higher velocity and muzzle energy with higher weight ammo. It's called Joule creep or energy creep. It's a common effect on GBB guns.

Yes you can use a non ported cylinder on a super short barrel. A ported cylinder will not necessarily give you less fps unless you drop below the magic ratio of cylinder volume to barrel volume to the point that you are undervoluming.