Tuning Inconsistent! Ugh!

[Widget23]

This pretty much sums up how inconsistent my Royale 500 0.25 is right now.

I adjusted the hammer spring a half turn from all the way in and the Huma regulator is at 145 bar. I filled the gun to 200 bar. I had 4 JSB 33.95 grain Mk II pellets in the magazine so I shot those. I'm using the FX pocket radar chronograph. 
Those 4 were: 898, 902, 898, 898. Pretty good, right?
Reloaded the magazine (same tin of pellets), and get: 886, 879, 865, 856, 856, 854, 847, 844, 823, 828, 800 ???? WTF?
Reload the magazine again and get: 830, 800, 786, 803, 784, 772, 779, 796, 782, 768, 749

Any ideas on what to do?

 

[nervoustrig]

If you are reasonably confident the regulator is operating correctly, and the hammer isn’t binding or experiencing sear drag, check your breech/bolt O-ring. When it’s just beginning to fail, it will cause erratic velocities somewhat under the norm.

 

[Guest]

That is a bummer. Hope you figure it out 

 

[18.13]

May be your hammer spring nut backing off.

 

[elh0102]

It's acting like a breech seal that's coming apart, although you would have probably heard a difference in sound by now. But, it's easy to place some tissue over the breech and see if there is any blow by when you fire it. Assuming the HST adjusting nut isn't backing off, try turning it out a half turn and see if anything changes. Is the Huma reg a new installation? I suppose it's possible one of the seals has failed.

 

[Motorhead]

Sounds as if your off regulation with each shot being slower than the previous .. textbook case actually.

 

[Widget23]

Sounds as if your off regulation with each shot being slower than the previous .. textbook case actually.

The bottle pressure is still 190 though.

 

[Widget23]

It's acting like a breech seal that's coming apart, although you would have probably heard a difference in sound by now. But, it's easy to place some tissue over the breech and see if there is any blow by when you fire it. Assuming the HST adjusting nut isn't backing off, try turning it out a half turn and see if anything changes. Is the Huma reg a new installation? I suppose it's possible one of the seals has failed.

The Huma is pretty new - but it could also be an issue.

I tried the tissue test and there was nothing obvious.

 

[elh0102]

If you haven't had a sustained satisfactory history with the "pretty new" Huma, that might be your best first avenue of inspection. But before removing and rebuilding or returning it, I would play around some with the hammer spring setting, just to easily remove one variable.

 

[Motorhead]

Sounds as if your off regulation with each shot being slower than the previous .. textbook case actually.

The bottle pressure is still 190 though.

Does it ? Only if the gauge is correct. Just sayin

 

[JW652]

+1

 

[Vetmx]

Do you know how to tune your gun around a reg setting? Sounds like you just guessed at a reg setting and guessed again at a hammer spring setting. Start from scratch and do it right. It’s not a quick process but it’s good info to have in your notes. The main thing is to know at what bar your hammer spring runs out of steam. There’s a couple ways to do it but unfortunately no shortcuts. 

 

[Vetmx]

It does appear that you are shooting off bottle pressure though. Which would mean somehow your reg is in the bypass mode or like Motorhead mentioned, you have a gauge issue. I recently dealt with a gauge issue and wasted a lot of lead. I guess I was in denial.

 

[jking]

You can get this fitting that screws into the stock retention stud hole and then add a gauge with preferably a bleeder inline to confirm your regulator pressure. Disregard the 194bar this one shows it was a bad regulator. 

Jking

 

[Odoyle]

Probably barrel breech seal or nicked regulator o-ring or not lubing with silicone divers "grease". Is it erratic throughout all 3 power wheel settings?

 

[SDellinger]

I have two FX500's and have considered getting one of them regulated. A person at AOA asked me why as it introduces a variable that can cause problems. Both guns shoot so well now I don't think I will regulate one of them. I bought a FX400 last year from AOA that is regulated. It works great and I hope it stays that way.

 

[Widget23]

Do you know how to tune your gun around a reg setting? Sounds like you just guessed at a reg setting and guessed again at a hammer spring setting. Start from scratch and do it right. It’s not a quick process but it’s good info to have in your notes. The main thing is to know at what bar your hammer spring runs out of steam. There’s a couple ways to do it but unfortunately no shortcuts.

Can you reference something that details how to do what you are saying?

 

[Widget23]

Probably barrel breech seal or nicked regulator o-ring or not lubing with silicone divers "grease". Is it erratic throughout all 3 power wheel settings?

Grease is correct. No, I've not tried the different power wheel settings. I'll investigate the o-rings though.

 

[Vetmx]

First off you just don’t set your hammer spring HS to almost max, set the reg to whatever then start shooting. Set your reg to 120b and back your spring way off and start shooting over the chronograph. Keep turning the spring until your gun doesn’t get any faster, then stop. If it isn’t fast enough, turn the reg up a little and do it again. When you finally get your gun to shoot around 20fps faster than you want, back the spring off to slow the gun down to the speed you want. If you have a HS wheel you can just turn it down from Max to 5 or 4. If you keep turning the reg up and your HS is maxed out but you can’t get 20fps over the speed you want then it’s one of 3 things. You don’t have enough HS to match the reg setting, your porting my be lacking or the speed you want might not be realistic. That’s the quickest way I can explain it.

 

[Vetmx]

If your gun came from the factory unregulated and you or someone else stuck a reg in it and didn’t know what they are doing, your porting could be severely lacking. I doubt the HS is lacking.