Sniper's velocity lowers during the day- it's gotta be in input regulator...right?

[tyronejk]

Wow, running out of options here! I also think this may be a good check:

Quick check would be to heat your gun up in a degassed state and with the trigger depressed, move the cocking knob and hammer back and forth in the lower tube, depressing the valve, while feeling for any binding.

[Cdn_Cuda]

Only thing left is to start swapping parts out. Start with the valve stem and see if you can see what part is causing the issue.

[latches109]

Run the marker at 280psi and repeat. See if you have the same drop in fps. Post a picture of your lower tube and one of the hammer.

[The Inflicted]

Run the marker at 280psi and repeat. See if you have the same drop in fps. Post a picture of your lower tube and one of the hammer.

I don't know if it's the mini-length body or what, but I've never been able to get this one to reliably function that low without the valve sticking open after a shot.

[superman]

That is typically the result of the hammer spring being too strong and or the hpr pressure being too low. I would check and see if the pump guide rod transfer hole is pointed downward towards the vert asa. I forget if it was the wwa kit or another kit that had flow issues.

[The Inflicted]

That's why I've usually run it at around 450psi. As long as the gun stays cold it shoots really happily at that pressure.
I drilled out the transfer holes in the guide rod a few years ago- there's four of them now, all larger than the ones he put in there originally. I was thinking it might make a difference in how low a pressure I could operate the gun at but it made no difference.

[The Inflicted]

Only thing left is to start swapping parts out. Start with the valve stem and see if you can see what part is causing the issue.

I used my last good 'cocker cupseal on another project but I've got one of the LP valves from autocockerparts.com on order, as well as some springs. I'll let you know if those fix anything.

[SR_matt]

saw you tried heating the valve stem, but have you tried heating the valve and stem together? wonder if something is expanding just enough to cause it to bind up (granted the hole should theoretically get bigger but this is a weird one).

And you checked the movement of the hammer when it's hot right to make sure it's not dragging? I know that was mentioned somewhere but may have missed you confirming if you tried that.

I would agree that it has to be something past the reg, the flow path doesnt make any sense as it's not like you're getting shoot down.

This really sounds like the issue people get with delrin hammers swelling but it looks like you have a metal hammer (plus I would just assume with the pressures you're running that you have a metal hammer). I am really leaning to something causing drag int eh hammer or valve as the only logical options.

One other thought, and this is kinda out there, any chance your frame screw is protruding slightly into the body? I don't know that the physics works for that only causing an issue when there is heat but maybe its just enough that the hammer expands slightly and drags slightly.

[The Inflicted]

saw you tried heating the valve stem, but have you tried heating the valve and stem together? wonder if something is expanding just enough to cause it to bind up (granted the hole should theoretically get bigger but this is a weird one).

And you checked the movement of the hammer when it's hot right to make sure it's not dragging? I know that was mentioned somewhere but may have missed you confirming if you tried that.

I would agree that it has to be something past the reg, the flow path doesnt make any sense as it's not like you're getting shoot down.

This really sounds like the issue people get with delrin hammers swelling but it looks like you have a metal hammer (plus I would just assume with the pressures you're running that you have a metal hammer). I am really leaning to something causing drag int eh hammer or valve as the only logical options.

One other thought, and this is kinda out there, any chance your frame screw is protruding slightly into the body? I don't know that the physics works for that only causing an issue when there is heat but maybe its just enough that the hammer expands slightly and drags slightly.

Screws aren't intruding into the lower tube. Checked with a flashlight and a dowel.

I tried leaving the valve and cupseal in the sun to heat up together, yes, but didn't notice any real sticking at the time.
I do think the problem is the valvestem dragging in the valve, though. The more I mess with it the more I think I can feel like the parts are binding if I hold them in a certain way and open the valve.

In the meantime, I've put the AutocockerParts.com red LP valve and springs in. I had a devil of a time getting the gun sweet-spotted with this combo as the gun really didn't want to shoot faster than 200fps and if the velocity adjuster was in much at all the valve really likes to stick open and vent after shooting. I could get it to shoot at just around 200psi, but the velocity would refuse to budge above 210fps or so. Eventually I cranked the pressure up to ~380psi and got decent velocity, but the valve still kind of wants to stick open but only if I hold the pump forward during shooting. I'm contemplating going to the heavier valvespring I had in there previously.

On the bright side, the temperature sensitivity seems to have gone away with the new aluminum valve and stem, which is really encouraging.

[Myrkul]

You could always try polishing out the valve stem too. I typically do that on most of my guns just because, but in this situation it might actually fix the issue. All you need is a cordless and the correct sand paper.

[SR_matt]

Yeah I was also going to say to try and polish up the valve stem. Really can’t hurt it and the only thing you would really do other than stopping any binding would be slightly opening the flow passages (but in this case probably not any measurable way).

[The Inflicted]

That might have fixed it, though I think a lot of the roughness was coming from inside the passage in the valve. I've got a lot less motivation to mess with it now that the new Red valve is doing its job.

[superman]

What gauge are you using for your regulator? I am starting to think that is way off or you are having regulator issues.

[The Inflicted]

What gauge are you using for your regulator? I am starting to think that is way off or you are having regulator issues.

I don't think it was regulator related. Both the Azodin reg and old Diablo Torpedo clone appear to be functioning properly. Even when the gun was warmed up in the sun the post-reg gauge on the adapter didn't move off its observed setting. Looking at them again I'm guessing pressure is more around 300psi. I'll probably bump it up a little when I chrono at the field next time I play.

Post-valving, here's the current reg output with a handful of gauges I've got lying around. I don't know that I trust the Diablo micro gauge.

[The Inflicted]

Can confirm that the new parts fixed the gun's issues with heat, though I had to boost the input pressure even further to stop the valve freeflowing after shots.

Thanks for your help and attention, everyone.

Now I just need to find some walk-ons that aren't frightened by the mean 'ol pump players.