Upgrades and Customizing - Velocity Adjustment

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Velocity Adjustment

Printed From: Tippmann Paintball
Category: Paintball Equipment
Forum Name: Upgrades and Customizing
Forum Description: Trick it out!
URL: http://www.tippmannsports.com/forum/wwf77a/forum_posts.asp?TID=176836
Printed Date: 08 August 2026 at 7:05pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com

Topic: Velocity Adjustment

Posted By: oldpbnoob
Subject: Velocity Adjustment
Date Posted: 14 July 2008 at 11:49am

Ok, so I have an old 98 that I filled in the front VA and put an RVA on. The FVA screw was still in, just unscrewed as far out as possible without interfering with the inside of the receiver. When I tried to chrono it, even with the RVA adjusted all the way in, I could not get it down below 320 or so which I know is considered unsafe. It was mentioned by another member (Mack) about getting a lighter spring. I also figured I could just take the marker apart, and screw the screw back in and work with the RVA until I got it low enough, or lower where I would be able to still use the RVA if temps rose and I needed fine tuning.

Anyways, here is my question if anyone cares. Going with the theory that the FVA lowers the FPS by creating turbulence with the air in the valve, would a more consistent shot be attained by removing the FVA screw all together and using a lighter spring as was suggested, or would there be any negligible advantages? Basically, would you get a more accurate shot without the turbulence created? Or does the turbulence help by adding spin? OOOrr, does the turbulence make the marker less effective, as you are having to increase VA to push the ball harder to overcome the turbulence?

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Replies:

Posted By: d4rkmonkey
Date Posted: 14 July 2008 at 3:25pm

Using a lighter spring with the velocity screw not blocking the air flow at all will give the most efficient result, but you need somehow to adjust it different than just a spring, like a regulator.

Posted By: paintballin37
Date Posted: 14 July 2008 at 3:51pm

oldpbnoob wrote:

When I tried to chrono it, even with the RVA adjusted all the way in, I could not get it down below 320 or so which I know is considered unsafe.

that's you problem... turn the RVA in for higher velocity. turn it out for less velocity. RVAs cant make your spring stiffer(higher velocity) but they can make your spring softer(less velocity) which is what you need. unscrew it and chrono it untill its at your desired velocity. you shouldnt need a spring kit if you have an RVA, for your situation.

Posted By: oldpbnoob
Date Posted: 14 July 2008 at 4:38pm

I turned the RVA both in and out with not enough effect either way.

The main point is in regards to if there is any significant accuracy or efficiency gain from using a spring kit with no FVA and an RVA or just adjusting the FVA in and using the RVA to fine tune.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Posted By: Mack
Date Posted: 14 July 2008 at 5:23pm

oldpbnoob wrote:

The main point is in regards to if there is any significant accuracy or efficiency gain from using a spring kit with no FVA and an RVA or just adjusting the FVA in and using the RVA to fine tune.

I doubt accuracy would be affected either way.

Efficiency is a different question. Personally, I would remove the FVA entirely, fill up the hole completely and smooth the inside if it to match the inside of the body shell. Then I would use an RVA for velocity adjustment. Removing the FVA screw entirely prevents the unlikely possibility that the screw might move due to vibrations related to firing and cause problems. Filling in the hole prevents any possible loss of efficiency from possible air-flow disruption caused by the unneeded "nook" in the valve. The RVA would allow you to adjust the valve to use just as much propellant as needed for your desired results.

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Posted By: Ilford Rule
Date Posted: 14 July 2008 at 5:52pm

Spring kit for sure. A regulator might also help. If you have a spare stock spring, you could try cutting it down a bit. A coil or two at a time until you get the velocity you want (leave some room for adjustment, so that you can increase the velocity with the RVA as the spring eventually wears out).

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CPro (w/ polished internals)
14" Bigshot
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Posted By: oldpbnoob
Date Posted: 14 July 2008 at 6:38pm

Mack wrote:

The hole is already filled in on the receiver, but I cannot get the FPS down with the FVA screw as far out as possible and the RVA out as far as possible. If I take the screw out entirely, I will definitely have to get a softer spring or cut what I have. If there is no neglible difference, wouldn't it be just as easy to screw the screw in, loctite it and use the RVA for fine tuning? I have never cut springs before and don't have a chrono at home to tinker with.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Posted By: Mack
Date Posted: 15 July 2008 at 2:22am

Not having a chrono to tinker with severely limits your options. With that in mind, a spring kit is probably the best option.

A couple of questions about your RVA:

Have you compared it to the stock end cap to see how the maximum adjustment positions compare to the stock spring location provided by the end cap? (I ask this because some RVAs are so poorly designed that they can't be adjusted to a position similar to stock. This results in either too much or too little tension on the main spring and no ability to adjust further.)
Is the RVA designed in such a manner that you can remove the knob and replace springs without having to deal with separating the body shells. (Most are; but I had one once that the knob wasn't removable on. I've put RVAs on markers before just to simplify spring replacement.)

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Posted By: oldpbnoob
Date Posted: 15 July 2008 at 12:02pm

I just compared the depth of the stock end cap hole with the RVA turned all the way in and they are really close. I am using a pretty primitive "stick a toothpick in the hole and mark" method, but they are very close. The RVA is part of a RAP4 wire stock. It's the marker that I have in the gallery with the pistol mag on the top.

I guess truly my next move needs to be to buy my cheap self a chrono if I am going to continue futzing around with my markers.

Regarding the springs, are there specific ones or would these (most likely) work: http://www.paintball-discounters.com/get_item_020977a.htm - http://www.paintball-discounters.com/get_item_020977a.htm ? I do have an extra spring around here, but I guess cutting it would be pointless without having a chrono to tell if the FPS is coming down.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Posted By: Mack
Date Posted: 15 July 2008 at 5:34pm

oldpbnoob wrote:

That's pretty much the same way I measure the depth of those things as well.

The RVA is part of a RAP4 wire stock. It's the marker that I have in the gallery with the pistol mag on the top.

I guess truly my next move needs to be to buy my cheap self a chrono if I am going to continue futzing around with my markers.

Having your own chrono is handy; especially if you play a lot of "outlaw" games.

I've always had good luck with the Maddmann spring kits but I'm not sure if they still make them. (Your link just took me to a page with a bunch of products so I can't comment on the specific set you were referring to.)

I do have an extra spring around here, but I guess cutting it would be pointless without having a chrono to tell if the FPS is coming down.

True.

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Posted By: oldpbnoob
Date Posted: 15 July 2008 at 6:32pm

Interesting. PBDiscounters apparently stopped carrying them from the time I posted and you read it. Story of my life. I found some on Actionvillage and they have Chrono as well. Another $75.00. Wife loves me.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Posted By: oldpbnoob
Date Posted: 19 July 2008 at 11:50am

Ok, so I finally bought a handheld chrono and some springs from Actionvillage. I took the FVA screw out entirely and wrapped the powertube with electrical tape to cover the hole. As mentioned before, the hole in the receiver is filled and pretty flush with the powertube. I used the softest spring in the kit and assembled everything. With the softest spring in and the RVA nearly all the way out, I still couldn't get under 310 consistently. Ugh. I pulled the marker apart, again and went rummaging and remembered I had an old spring from my other 98C/ACT that a shop replaced when fixing it. I compared this spring to the stock and softest spring and it was shorter than both. (BTW the stock spring that I was using was actually shorter than the one I was replacing it with from the kit). I reassembled and now I am pretty consistently under 280, but it is still fluctuating a fair amount.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

Posted By: Mack
Date Posted: 19 July 2008 at 4:05pm

The fluctuations could be due to the CO2; especially if you are using 12 grams.

P.S. This project of yours inspired me to dig out my Black Maxx based CQB marker project that I haven't messed with for a while.

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Posted By: oldpbnoob
Date Posted: 19 July 2008 at 8:45pm

These fluctuations are coming from a 9oz. Would a reg or stab help?

I would love to see pics of your project. To be honest, I haven't a clue what a Black Maxx is, but sound interesting.

I ended up putting a longer barrel on that I had laying around and extended the stock to fit me. I like it, but it's kind of a beast.

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"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.