Weird Classic RT problems today

Well, ran into some weird problems with my Classic RT on the field today and don't know what the problem is. My setup is a Classic RT, Lvl 10 with no shims and the red springg, with a 68/4500 Ninja SHP tank set to 950psi. I just bought a brand new reg piston for this gun from AGD this week so this seems all the weirder. I chronoed the gun fine in the 285fps range, but had several instances were the gun refused to fire when I pressed the trigger, even though I could feel pressure pushing back on the trigger. This might be a seperate bolt stick issue. However, a little while later it started to shoot very hot, 320fps, and I couldn't chrono it lower or the gun wouldn't cycle. When I tried to screw in my reg nut all the way in to see if the piston would vent out the back, it never would vent. I thought that was very odd. Did I buy a bad reg piston from AGD?

The gun refusing to fire when the trigger is pressed, when it would fire before, is usually a bolt stick issue. It usually occurs when you attempt to fire the gun after a brief period of no firing. I suspect if you use the next larger carrier size, this problem will go away.

When it won't fire at a lower velocity but does at a higher velocity, is usually due to using a bolt spring that is too stiff. If you happened to use a different barrel, the changing pressure requirements will change the lowest velocity that the gun will cycle at. You may have to use a different bolt spring or cut one to suit your barrel needs.

The shooting hot issue when it was chronoed lower, is usually related to the regulator seat oring leaking. A small leak will often produce a hotter first shot, but subsequent shots in rapid succession will be around the preset velocity. If every shot is hot, then something has changed. It could be that something wasn't completely seated when you first chronoed and then settled into place or it could be that something is interfering with the movement of the regulator piston assembly. Clean the cavity out in the back in case a piece of dirt or sand has gotten stuck in there. A complete clean of the valve wouldn't hurt for the same reason. Its a quick and inexpensive thing to do and usually fixes most problems.

Given that your gun is a classic RT, the springs that push on the regulator piston are probably weaker. That combined with a higher pressure release of the piston assembly means that the chamber pressure may not get high enough to cause the regulator piston assembly to vent air out the back. I wouldn't worry about that.

In review, I would clean first. Then I would tune my level 10 setup again.

Thanks for your thorough help athomas,

You hit on several points that make sense. I tried installing the next larger size carrier last night and it was leaking, but I suspect that if I dry fired it several times it would seat and eliminate the bolt stick.

Also, I suspect you are right about the spring being to stiff. I was actually using a brand new red spring, having mostly just used gold springs previously, and was surprised by how stiff it was comparatively. I might need to trim it shorter a little bit.

I'll recheck my reg seat oring and clean out the valve again just in case. When I got this RT, it was in practically brand new condition. The valve is pristine but I went ahead and replaced the reg piston, reg pin, and valve springs just in case so I knew everything was fresh. You were right when you said the original RT springs were probably weaker. The original RT valve springs were a smaller diameter than the current ones made for RT/X valves with Lvl10. So this RT valve has the larger, stouter springs which is why it was confusing to me that it wouldn't vent when the reg nut was turned in all the way.

Do you think that could be a problem with this new reg piston or no? Maybe if I solve the spring issue, the velocity issue will be taken care of.

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Originally Posted by Konigballer

Do you think that could be a problem with this new reg piston or no? Maybe if I solve the spring issue, the velocity issue will be taken care of.

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I doubt there is a problem with the reg piston. Sometime you will just bottom out before you reach high enough pressures to cause it to vent. It will still protect you against high overpressures and super hot shooting.

Before trimming your red spring, make sure you are in the correct velocity range. If the gun starts cycling 20fps below the velocity you want to shoot at, then it will work fine.