RT Valve and X-Valve velocity inconsistency issues

[ghost flanker]

I seem to be getting velocity inconsistency from all 4 of my RT style valves (two X-Valves, a ReTro valve, and a classic RT valve). I’m getting velocities from the X-valves and ReTro varying between 235 and 290 FPS. I’ve tried swapping out everything: the reg seat, reg valve pin assembly, reg piston, everything. Nothing is making a difference. I’d say that maybe it’s the paint but I’m getting good consistency with the same paint out of my classic minimag and hammer 7. I can’t imagine what the issue could be.

I’m using a chronograph like this one
Used Sports Sensors Paintball Radarchron Chronograph Free Shipping!! https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F26 4465368547
shooting into a hanging sheet.

Any ideas?

[Tunaman]

Are you chroning it correctly? hold trigger back...shoot fast and hold trigger back...repeat.

[TheRealKaz]

Are you using the same barrel with the 4 you're having issues with? My guess is it's paint to barrel bore match issue.

If you can, use a different barrel with each and see if that changes your velocity.

[ghost flanker]

Are you chroning it correctly? hold trigger back...shoot fast and hold trigger back...repeat.
When chronoing correctly, yes, the velocity tightens up to a normal velocity spread: about +/- 5 bps. But when shooting normally as one would during a game, the velocity varies wildly to a concerning degree. Normally, the velocity spread seen in this manner of shooting is roughly +/- 10 bps, maybe +/- 15. But +/- 30? Something’s gotta be wrong here.

[ghost flanker]

Are you using the same barrel with the 4 you're having issues with? My guess is it's paint to barrel bore match issue.

If you can, use a different barrel with each and see if that changes your velocity.
I’ve used multiple guns with multiple barrels, swapping out the RT valves with classic valves. The problem seems to follow the RT valves and resolves when a classic valve is installed, regardless of which barrel or gun is used.

[ghost flanker]

And the manner of the velocity swings are odd. Sometimes they follow a pattern where I’ll have several shots within a normal spread mixed in with an occasional super low velocity shot. Other times I’ll be shooting several shots in the 240s, then several more in the 260s and 270s, then a few in the 290s, then a few more down in the 240s and 250s again. It’s really frustrating and seems to have no apparent cause.

Also, sometimes when adjusting the velocity, I’ll make a quarter turn with no difference in velocity. I’ll try several more quarter turns, each with no difference in velocity, then I’ll give it one more quarter turn and suddenly it’s shooting insanely hot, like in the high 300s or low 400s. This doesn’t happen every time I adjust the velocities, but it does happen.

[luke]

Are you using the same tank/reg all around?

[ghost flanker]

Are you using the same tank/reg all around?
I’ve used multiple tanks to see if the problem follows the air source. It does not.

I’m using a Ninja SL at 900 psi, a Ninja V2 SHP at 1100 psi, a 4500 Empire at 850 psi, and an old 3000 Crossman. All produce similar results.

[Xyxyll]

Long shot, but also investigate your entire air path from tank to valve. Maybe there's some obstruction somewhere that's loose, causing intermittent velocity changes or shoot down? Some gas through grips and all Classic RT hardlines had air filters on them that can get clogged over the years.

[TheRealKaz]

Mmmmmmm inconsistent/worn out bolt spring? Are you using the same bolt spring on the X-valve/rt valve?

[ghost flanker]

Mmmmmmm inconsistent/worn out bolt spring? Are you using the same bolt spring on the X-valve/rt valve?
I’ve swapped bolt springs and bolts.

[Tunaman]

Time to rebuild the reg section of the valve

[TheRealKaz]

Time to rebuild the reg section of the valve

Yeah it seems like that's the only thing left.

[ghost flanker]

I’ve already replaced the regulator piston and regulator seat with no difference in performance. Do I need to replace the springs inside the regulator?

[TheRealKaz]

Yes

[ghost flanker]

I think I finally figured it out. It seems my inconsistency issues between the four guns in question were actually a combination of any or all of the following culprits;
- Reg springs were super dry in all four guns (probably main culprit). Greased springs with Dow 33.
- A bad reg valve pin assembly in at least one gun. Replaced.
- Slightly bent ULT shim in one gun causing varying degrees of short stroking as well as a delayed bolt reset. Replaced.
- Level 10 bolt weld spot possibly rubbing ID of Docs adapter in one gun. Dremeled bulge on L10 bolt for a flush surface.
- Reg seats. Replaced in all guns just for good measure.

The X-valve in my main gun had all 5 of these issues. It’s been a while since I’ve been this frustrated with an automag, but now it’s shooting with a velocity spread of roughly +/- 8 FPS.

[Xyxyll]

I think I finally figured it out. It seems my inconsistency issues between the four guns in question were actually a combination of any or all of the following culprits;
- Reg springs were super dry in all four guns (probably main culprit). Greased springs with Dow 33.
- A bad reg valve pin assembly in at least one gun. Replaced.
- Slightly bent ULT shim in one gun causing varying degrees of short stroking as well as a delayed bolt reset. Replaced.
- Level 10 bolt weld spot possibly rubbing ID of Docs adapter in one gun. Dremeled bulge on L10 bolt for a flush surface.
- Reg seats. Replaced in all guns just for good measure.

The X-valve in my main gun had all 5 of these issues. It’s been a while since I’ve been this frustrated with an automag, but now it’s shooting with a velocity spread of roughly +/- 8 FPS.

Glad you were able to finesse it back into a normal range! Thanks for sharing your solutions.