Gun Trouble

[Shadowrich]

[LawVol]

[Shadowrich]

[bigb]

I'm 100% sure there is nothing wrong on the compression side of our guns. Three guns came up around 300 with the same spring says the .05 gram difference in bb weight is causing the velocity drop. I'm gonna drop in a set of prometheus gears, big spring, and make sure i shim the gears perfectly.

B Rich; just for reference, Guarder makes an air nozzle with an oring in it.

i just had an idea; were you testing your fps with your hopup on, or off? mine was on i believe.

[lawofthirds]

[ParaTweeT]

Now after talking with Shane a bit and doing some testing I would look at your "custom O-Ring Nub". If you all are using that it could be causing too much resistance and thus your significant loss in FPS. I lost almost 24 FPS by using an O-Ring Nub in one test. Different size O-Rings and different hop-up chambers are all going to give different results. From a field tech perspective a new hop-up bucking that comes with the nub (check the package to be sure) is a good start.

As for the comment on P90 inner barrel being short. Well that might be the case if it was not an extended inner barrel. Also your inner barrel length has more to do with Accuracy than FPS. The only counter to this would be if you do not have enough volume in your Cylinder to fill that barrel you would end up with barrel suck and loose huge amounts of FPS.

For the 25% loss that is waaaayy to much of a loss for a .05g change. With that theory you would get far less fps than anyone does. General rule of thumb (without the long formulation) is 50fps loss per .05g increase. With 25% loss that means one of my M4's shooting 400 FPS would be shooting 300 FPS with .25's. Increase the spring and your increase in loss would occur. This just is not the case as anyone who has more than a few guns would attest to. I personally have 4 M4's, 1 P90, 13 AK 47's, 2 MP5's and a few others. With nearly all of these guns I have chron'd both .20's and .25's and the base of 50fps loss with the .05g increase is pretty close (often its less than 50fps loss).

[lawofthirds]

25-20% sounds right in my book since both my chrono's of a stock tm g36c support that figure. You're adding 25% weight so a corresponding drop in velocity should be seen.

And while I'll agree that barrel suck kills fps quicker than anything, look around and you'll see that much higher fps results can be achieved with longer barrels on similar or identical guns. You will not get 400fps with the same upgrades in a mp5k that you would in an aug or m14

[Hunter]

List the brands of the parts you put in. Gears will not raise your FPS so don't get confused. Also did you put some lube around the O-Ring? I am not talking about silicone oil but actual lube. If you still have problems put your old hop up unit back in. No two companies parts are the same so you might be losing velocity because of that.

[bigb]

silicone lube gel; lemme assure you i'm pretty confident between the three of us its not user error. Three different hop ups;

marui stock
ics stock w/ prom soft type
systema

[Shadowrich]

I am the only one using the "custom o-ring" hop up bucking. The absolute only conclusion I can come down to is the bb's. We all used the same bb's and came out with similar results. My brother using an m120 with the same bb's came out at only 330 fps.

Just to remind everyone again there are three different guns coming out at 300 fps +/- 3 fps. There has to be some common factor that is bringing us down. As for barrel suck I don't think it is the problem. I am using a type 0 cylinder with a 509 length tightbore. Brett I believe is using a type 1 or type 0 cylinder with a standard m4 length barrel. Rodriguez is using a standard m4 length barrel with a hurricane cylinder. I believe Brett is going to airsoft knoxville tomorrow to show whoever is there his gun.

[ParaTweeT]

What brand are you all using?

[bigb]

[Streak]

[bigb]

i dont' see how three guns with different parts cronoed 300 +/- 3 fps.

I'm using
Prom 363 tightbore
Prom soft type sleeve/bucking
systema polycarb piston
systema polycarb pison head
type 0 cylinder

in an ics m4.

I still don't get my i'm only getting around 300.

[Streak]

My guess is that the tight bore barrel is the problem. The stock ICS barrel always gave me more fps than any tight bore. The o-ring on the ICS barrel makes a big difference. Just for fun switch it back and then chrono.