Chronoed my pp700sa

I would say thats not a bad spread. Lots of factors to consider including pellet weights and your chronograph. In my opinion....Acceptable.

I've been tuning my pistol all day today trying to get a good tune in the 7 to 8 FPE range. 4 fps is the typical standard deviation I get over a 50-60 shot string with an extreme spread in the 20's when tuned between 10 and 12 FPE. I have the Huma regulator installed and set somewhere around 75 BAR.

Here is a graph of my latest shot string: Ignore the standard deviation and spread. The standard deviation hovered around 6 fps until going off the reg at shot 82 with a spread in the low 20s. I seem to be getting a couple mini curves in my shot string before it goes off the reg.

Luis, I'd say yours is doing great. That is very good consistency considering:

1. unsorted Crosman pellets

2. no tuning done

3. regulator is still pretty new

The only bad news is it doesn't leave much room for improvement! I'm happy for you. I had to really work at it to get mine to do that well.

mmahoney, that double bell curve does look odd for a regulated gun but the overall ES looks pretty good so I wouldn't be concerned.

The velocity rise toward the end of the shot string is saying the hammer strike is adjusted a smidge too light. Try dialing in more preload until you find the point where the velocity no longer increases and then back it down to 95 - 97% of that maximum velocity. When adjusted in this manner, the gun will produce a tighter ES and a gentle rolloff as it falls below the regulator's setpoint.

The resulting energy (fpe) will be a bit more than you have now, and a corresponding slight reduction in shot count. If that is not desirable, you can reduce the regulator's setpoint to bring the velocity down (and adjust the hammer spring as described).

Good luck!

I'm a newb when it comes to the chronagraph game, 
but I did just get one recently, so I'll send a few strings of pellets across mine, and compare numbers as soon as I can.
My PP700S-A is also fully stock as far as adjustments are concerned. It'll be interesting to see what we come up with.. 

 

Sam -

You guys are killing me I just picked up a Flashpup in 22 and said it would be my last PCP for a long time and then this thread I read....This is a very nice setup and looks like a lot of fun to shoot. Then of course I learned near the end of the year it looks like they will have a magazine version....buy or wait is now on my mind.

Tony P.

I have a 74 cu ft tank for a Taipan in 25, marauder in 25 and now the flashpup in 22...My problem is I like to tinker on them and once set up I need a new project...And I just started this addiction maybe 5-6 months ago....

Tony P.

@nervoustrig

I'm sure you are not suprised to be proven right. I want to get the pistol as low powered as possible. I've found it doesn't take much to bring down birds at close range. I have on occasion seen my pellet ricochet through the bird and hit with considerable force in unpredicable directions. I've also been known to miss and want the pellet traveling as short a distance as possible in those not rare enough occassions. The pistol is so easy to fill that shot count is not a consideration. So....

I lowered the regulator pressure to around 70 BAR (even though HUMA says not to lower it below the provided scale). Pellet velocity actually rose with the lower reg pressure suggesting that hammer spring tension was indeed way too light. I shot a couple stings but the standard deviation was still around 6 with a spread in the low 20s. So I tightened the hammer spring a little bit and the following tune fell right in my lap:



I didn't expect this sort of great consistency. I think I'll fiddle with tightening the transfer port adjustment screw and see if that lowers the velocity while maintaining the consistency.

Tightening the transfer port got me to my goal of 7.5 FPE. The first 3 full revolutions of the screw did not make a difference. The screw starts to constrict air flow only after the first 3 full revolutions. A longer threaded screw might me nice.