Panthera 500 .177 high spread and SD

[merpo]

Hi all,

I unpacked brand new Panthera 500 in cal .177 and put first shots through it.
I wanted to tune it to sub 12 fpe and to my surprise right out of the box it was almost tuned to what I wanted.

Did a few clicks on macro adjuster and I was shooting <12fpe.

Regulator set to 80bar
Macro 8
Micro 2.5 (or something around)

I am getting high spread in fps, look at theses 38 shots:

Shot count: 38
Low: 691
Hi: 775
Avg: 732
Spread: 84
STD Dev: 21.0
691
719
742
735
728
733
738
703
742
726
726
726
724
717
721
705
698
717
721
705
707
772
775
749
763
763
756
770
749
749
733
740
710
740
733
742
717
740


Any idea why and what I can do to fix it, if anything? Before I sent it back, I want to see if there’s anything I can try to make it the way I expected it to be (<5 fps sd).

Thanks!

 

[Airgunmann]

I'd try upping the reg some get a shorter burst of high pressure air

 

[GA_LeadHead]

I'd try upping the reg some get a shorter burst of high pressure air

Bingo

 

[weevil]

Is the reg staying at 80bar as you shoot? The Panthera regs seem to work best at 150bar+. The belleville washers in the reg are setup that way and your reg may be struggling at 80bar with very slow recovery. I’ve restacked my washers in the 600mm 177 Panthera and it’s doing much better (running at 115bar). I was told that they’re doing this at UA after a bunch of people have complained about the slow refresh and creep when running the lower pressures.

 

[merpo]

Thanks all for your suggestions.
I tried to increase the reg pressure from 80 to 110 in 5 bar increments and it behaved basically the same.
I lowered the reg pressure to 95 then and I see some improvement however it’s far from what I expected it to be.

Shot count: 30
Low: 719
Hi: 812
Avg: 786
Spread: 93
STD Dev: 17.1
719
765
772
796
796
793
784
784
789
784
796
789
793
786
770
775
772
775
775
786
782
789
796
789
807
796
803
800
812
803

Notice the low fps of the first 2-3 shots. This is repeating after I leave the rifle untouched for about 1 hour and come back shooting. Anybody experienced this?

The reg pressure seems to be staying at the set pressure, the recovery is fast or not noticeable. Plus I’m not shooting from the magazine, mainly because it’s not cycling so I’m loading the pellets manually which is ok.

 

[Airgunmann]

Probably a balance valve in there and there is some sticktion from the orings on the first 3 shots happens in a lot of guns with balance valves on the impact there was a work around using a peek spacer in the power plenum or you could tune most of it out by tweeking the hammer spring a tad tighter I'm not sure on the panthera haven't been inside one yet

 

[weevil]

2.5 on the micro is a lot of hammer for such low reg pressure and it is possible that your running beyond the peak of the HST curve. You could see where you’re at on the curve by setting the reg to 80 or 90 and then checking the speed of some shots at micro 2.5, 2.25, 2, 1.75 and 1.5. Just leave the macro in the middle and only adjust the micro.

As an example, when I shoot Zan 13 grain slugs at 980fps from my 177 600mm, giving ~27fpe, my reg is at 100bar and micro wheel is at 1.8, which is right on the knee of the curve.

I’ve not seen any slow first shots like I do with my M3, but my understanding is that the M3 stiction (as described above) only happens at high reg pressures.

 

[weevil]

Also, you’re shooting at such low power that it’s going to be difficult to assess the reg performance. Anyway, I would first check where you are in terms of tuning as described above, because if you’re way over hammered, all kinds of crazy stuff can happen. I strongly suspect that you are because even at 80bar, that gun should be shooting at 20+ fpe at its HST peak.