[Hebiki]

chrono: 260fps
orings: polys on the valve and power tub.
OP: 100psi

been used for 2 cases and dry fired for 2000psi.

tournament this sunday.. ill chrono up to 295 and check the OP then. after the tournament, everything should be perfect since I'm expecting to shoot 4-5 cases.

[acabello72]

Eric was saying that if you're using poly's, it takes roughly 8-10 cases to break them in. 4-5 is for vitons.

[Hebiki]

Mark_S....post the picard meme.

[lewis314]

I just hit 6 cases on my polys and will say it set started to feel like it smoothed out. Also extra lube is a big help.

[Mark S.]

Originally Posted by Hebiki

Mark_S....post the picard meme.

lol here ya go, I can't take credit for this, it's all Hebiki

[seriouslysilly]

Lol

[acabello72]

Originally Posted by Mark S.

lol here ya go, I can't take credit for this, it's all Hebiki

Well doesn't this just put everything in perspective. Lol

[aan310]

How are we supposed to tell if the oring fits correctly or not?

I swapped over to Viton rings on my vale and powertube and it destroyed my VXs shooting ability.
It was shooting between 50-250fps (and all over the board, not consistently both ends of the spectrum). Simply switching back to the original orings got me back to 280 +/- 10
The viton o-rings appeared to fit fine, what's the catch im missing?

[Mark S.]

I'm guessing that maybe there were a little too big making things too snug. Try changing out just the valve o-rings or the powertube o-rings and leave the factory ones in whichever you don't swap. That way you can at least know which is causing the issue (assuming it's not both).

When putting them on, use more lube than usual until they are broken in a little bit. When I install them I do them one at a time and slide either the keg or the bolt (depending if I'm doing the valve or powertube) over them to see how much friction I'm dealing with. There should be friction, but not a ridiculous amount. You should be able to tell if it feels abnormal or not. Do it with the stock o-rings first so you know what that feels like. The new vitons will obviously have more, but it will help you know how things feel.

[Killer Carton]

So not to necro post but I have been having some issues with my GT and I think its because my o-rings have finally worn out. I am planing to do a full rebuild on the dynamic o-rings and after rereading this thread I think I am going with all polys except for viton on the bolt switch and inner spacer o-rings.

Two Questions:

Is this still thought of as the optimal setup, if not what is?

Why not run viton on the bolt keg inner o-ring if in fact you want minimal friction on the bolt?

[SHOOTNPOO]

Inner spacer, front keg Inner Use BUNA ONLY

Vitons on inner bolt keg and spacer will created to much friction and you will have to raise your internal pressure. Ultimately defeating what you are trying to do.

[Killer Carton]

Originally Posted by blueshifty

The parker guide covers it in great detail, but:

Running Friction (Coefficient): - this the rest of the stroke once the bolt gets moving
Urethane < Viton < Nitrile (Buna)

Breakaway Friction: - this is the very first shot in a string (mostly has to do with compression set and durometer)
Nitrile (Buna) < Viton < Urethane

Abrasion Resistance: - this is the best indicator of life expectancy
Urethane > Viton > Nitrile (Buna)

So, manufacturer information implies that for our application Urethane > Viton > nitrile (Buna)... Throwing around anything else is purely conjecture. Like I said, you guys are free to call oring manufacturers and get their take on it. Also, factoring in cost often makes compromises.

If James would tune in, if he is the quality of engineer I think he is then he also looked at the compression data and surface finishes to reduce friction by adjusting tolerances. In my old life when I did industrial design (straight out of college) it was common to design things from a functional standpoint then go back and optimize the design and assign machine tolerances.

Im assuming bunas on the inner bolt keg and inner spacer due to them having the lowest breakaway friction? But buna also has the highest running friction so why not go middle of the road and use vitons?

[SHOOTNPOO]

Here ill make it simple.
You can not trust oring manufactures and the specs they give in tolerances per material they use. You ar just waisting time and money trying to hand fit 2 orings out of 1000. When buna in these positions have been tested time and time again.

[Evil Rocky]

I alwayswanted this, but how well my GT has been shooting just makes me not want to change my orings. I have about 40-50 casesthroughit already.

But either way I orderd them and hope makes a difference i can notice.

[Evil Rocky]

I got my fitted rings today.

The clear/white orings go on the valve right..... Only ones I have not changed yet is my outside orings yet.

I changed all oringg that bolt glides on. So my bolt and circular back piece that has one oring? The one right behind bolt thing(forgot name), power tube and inner valve from back keg. Am I missing anything?

[SHOOTNPOO]

Only change
Power tube Viton or polly
Valve, viton or polly
Bolt, viton or polly

The spacer (silver thing behind bolt) use buna oring
The frontinner bolt keg use buna also.

[Evil Rocky]

Viton R the white ones right.... that's what I put on my valve

[SHOOTNPOO]

Clear ones are Pollys, you must of got one of the kits our new guy put together with no Labels. Here is a photo to help you. I'm sorry about that it was my mistake to not catch it before it shipped out. We caught it after a couple left.

[Evil Rocky]

Yeah no labels. Some orings where mixed, but no big deal.

Pictures help :-) any way can get pic of bolt what orings U have on your bolt? If not no big deal.

Thanks

[SHOOTNPOO]

I use the Vitons personally.
Power tube 011 x2
Bolt switch oring 016
GTI valve Vitons 017 x3
The rest are bunas

[Evil Rocky]

JUst a quick uopdate from Sunday

The gun had a lot of drop off when holding streams of paint. But after I put 2 hoppers through teh gun was shooting perfect. At about my second case my FPS changed and had to lower it. I think maybe my orings sat a little bit.

But I put 2 cases on sunday and I have 3 more cases at home and tomorrow going to shot at least 1 case to keep break in and will keep everyone updated on my results.

My gun has GTi Valve, pooty bolt, dwell 8, shooting 285-290 using a .684 DYE UL barrel 68ci 3700 psi ninja tank with all shims out. It has first gen noid and no problems.