Sporadic FPS

[Madcat_MK2]

Hello all. I've have my ULE Custom for a little while now and have shot a couple of cases through it with the same o-rings. I've gone down a few carrier sizes since too since I started breaking it in. My problem now is my mags speed fluctuates pretty badly. I'll get two rounds to shoot at 280, then one goes 302 then 290 then 315, back to 280 again and it kind of continues. I usually just leave it so it maxes out at 285 fps, but it averages more at 260's.

The valves seems to be in perfect shape as I pulled out the velocity pin once to check it, and checked the little oring to see if its sitting right on the stem in the middle. The only thing I have noticed that is peculiar is sometimes it will leak air down the barrell noticably, but then if I fire a few rounds it usually stops. I'm using no shims, red spring and I believe .5 carrier. It fires great despite the sporadic FPS and occassional leaking.

Do you think the bolt o-ring is grabbing inconsistently enough to just work, but is causing my FPS to jump around and the occassional leaking I get? Would trying next size down be next thing to try or switch to another oring and start sizing all over again? Thanks for any help.

[lidocaine]

My tac one is the same way, just as you described. Looking for a solution as well.

[lidocaine]

Bump for justice.

[secretweaponevan]

You definitely want the largest carrier that doesn't leak.
Bump up .5 a carrier size (use the same carrier o-ring in it) and see if it still doesn't leak. If it doesn't, repeat.

Other than that it is probably a paint to barrel match. If you don't have a barrel kit there is not much you can do. If the paint isn't round, fuggedaboudit. I was shooting footballs this weekend and my velocity was +/-10fps.

[lidocaine]

wow plus minus 10 is on a good day for me..
Im going to test my JJ barrel kit this Sat. hopefully that clears it up.

[secretweaponevan]

wow plus minus 10 is on a good day for me..
Im going to test my JJ barrel kit this Sat. hopefully that clears it up.

It should if the paint is round and you chrono properly (if using an RT valve).

[athomas]

Take the shims out to make sure you aren't getting leaking due to the bolt stem vent hole being too close to the oring. Then go to the largest carrier that doesn't leak.

Check the roundness of the balls you are using. Use a larger barrel to compensate for odd shaped balls.

[Madcat_MK2]

I'm not using any shims as it vents just fine without them. If I go one carrier size up it leaks horrendously so this one should be right, but it still does that sporratic leaking. I was under the impression that if the oring is sized right that it never leaks down the barrel unless it comes time for a new one?

I dont have a barrel kit as Im just using a j&j ceramic, but the balls we've been using are pretty good and fit fine in my barrel. Another guy on my team, I forget his name that he uses on here, doesnt seem to have any troubles using the same paint and I dont recall him using a barrel kit either.

[TheRock]

is your hpa system in good shape?
If i chrono not using the rt way its low fps and big variations, but if i chrono it like you should its only a few fps difference sometimes only 1-2 fps with a paint/barrel fit that paint barely touch insides of barrel.
im down to smallest carrier and same oring about 30 cases through it now, i feel the autolube is not the best for long term lubing because i get bolt stick after 2 cases after a fresh lubing.
and one dot carrier is to large its not leaking when first gassed up but after first shot it leaks badly.

Nothing but pleased never had to stop playing because of equipment since i went tac one.

[athomas]

... i feel the autolube is not the best for long term lubing because i get bolt stick after 2 cases after a fresh lubing.
and one dot carrier is to large its not leaking when first gassed up but after first shot it leaks badly..

That's bolt stick caused by a carrier that is too tight. Go to the next larger carrier size. Don't forget to remove all the shims so you don't get shim induced leaking that seems like a carrier leak.


Madcat_MK2: Take the regulator piston assembly out of the back and clean the back of the valve. Grit in there could cause fluctuations in velocity.

[Madcat_MK2]

Nah, I got a brand new Crossfire 900psi output tank, so that is good.


Athomas, you do mean to take out the velocity pin again and clean inside there along with that spring pack, correct? If it is, what should I use to regrease them again when Im done cleaning them? Does any paintball gun grease suffice?

[lidocaine]

Im running a 850psi output tank.
I cant seem to get it to bounce the "rt" way.
Does it really matter, if its good consistency when bouncing wouldnt it be good when its not?
All your supposed to do it pull the trigger once, hold it, release, quickly pull trigger again and hold it on the sweetspot?

edit: if thats not true, what is the proper way?

Thanks

[lidocaine]

I just searched for proper chrono procedure.
Fire, hold trigger, fire quickly again and hold trigger again, fire again. repeat, correct?
Why wont the gun shoot consistently when shooting normally, because thats not how I would shoot in a game..

[secretweaponevan]

I just searched for proper chrono procedure.
Fire, hold trigger, fire quickly again and hold trigger again, fire again. repeat, correct?
Why wont the gun shoot consistently when shooting normally, because thats not how I would shoot in a game..

The above procedure mimics rapid fire. The air recharges in an RT valve so fast that it heats up , increasing pressure and therefor velocity. To chrono an RT valve slowly would allow you to shoot hot during rapid fire.

[lidocaine]

Alright I understand that I would be shooting hot if I didnt mimic rapid fire like the above procedure, but shouldnt the consistency be as good when your slow firing as you are when rapid firing because I cant even rapid fire more than 2-3 shots no matter how hard I try, thats crap if I have to live with 25fps jumps because I cant rapid fire 10 balls a string.
Dont most people shoot x vavlves semi auto one shot per pull when in rec games and such where 15 bps isnt necessary? Is their consistency horrible too?

Thanks!