Discovery Chrony Numbers With Power Adjuster

[air rifle hunter]

Hey guys!  I chronied my .22 cal Benjamin Discovery today and played around with the home-made power adjuster untill I found where it gave me the best numbers.  Let me know what you think of the numbers.  Do you think they're a little low or are they pretty good?  I was using 14.3 gr. Copperhead Domed pellets which aren't the best, so my guess is the numbers might be slightly better with a higher quality pellet.?

2000psi fill  (shot down to roughly 1100psi)
14.3 gr. Copperhead Domed  (.22cal)

1)  909.0                                                                                  
2)  926.0
3)  907.4
4)  923.1
5)  1023.0  (I think a fluke)
6)  882.1
7)  879.4
8)  879.4
9)  863.3
10) 862.8
11) 846.5
12) 837.2
13) 818.0
14) 814.1
15) 871.6
16) 842.5
17) 815.2
18) 809.5


Brian

 

[preez]

Brian, I think you might have compressed the spring a bit too much. The numbers are inconsistent, and there is no curve to the numbers. To set your "peak" velocity fill to 1600-1800psi and see where you max out fps wise. For my liking you should start at 860-875 on the full 2000psi fill, slowly climb to 900's and then go down to 860-875fps again at 1000-1200psi. For the best long range consistency your shots should be within 20-25 fps from each other, you are kinda all over the place. Another thing to pay attention to on the Disco is trigger pull while you chrony. You might have a sear drag happening. Pull the trigger the same way every time you chrony a shot.

Hope this helps

Chris

[air rifle hunter]

Hang On Guys.  I forgot to mention that I was doing the chronographing outside yesterday.  That was the problem.  I just started chronying indoors today with some good, proper lighting and my numbers so far are very consistant.  Way better than yesterdays.
I'll post the TRUE numbers later so stay tuned!

Brian

[air rifle hunter]

The measurement on the numbers is a little more consistant and reliable this time around.  I've adjusted the power adjuster to where I get the highest average velocity for the first 10 shots and where my extreme spread is still acceptable.  I am a hunter through and through, and when in the field hunting, I rarely ever take more than 5-6 shots.  So the numbers I'm getting are excellent, in my opinion, for what I need.  (mind you the POI does not change enough to worry about even when taking 20 shots.  All shots are still within 1/2" with the slight change in POI)

NO POWER ADJUSTER                                                      
14.3 gr. Copperhead Domed                                                  

1) 796.0        2000psi                                                              
2) 799.9                                                                                    
3) 807.4                                                                                    
4) 811.0                                                                                    
5) 813.9                                                                                    
6) 818.4                                                                                    
7) 822.0                                                                                    
8) 820.1                                                                                    
9) 821.2                                                                                    
10) 823.7                                                                                  
11) 824.7
12) 821.4                                                                                    
13) 829.0                                                                                                                
14) 825.7
15) 823.3                                                                                  
16) 824.5
17) 813.0                                                                                
18) 810.8                                                                                      
19) 811.3                                                                                    
20) 808.6                                                                                                              
21) 793.1       1200psi
                                                                                                   
Ave. for 1st 10:   813 fps
                             21   fpe

Extreme spread:  35.9 fps


WITH POWER ADJUSTER
14.3 gr. Copperhead Domed

1) 903.4             2000psi
2) 904.5
3) 908.4
4) 901.6
5) 899.7
6) 897.7
7) 890.3
8) 884.5
9) 880.0
10) 872.2            1500psi

Ave. for 1st 10:   894 fps
                              25   fpe

Extreme spread:  36.2 fps

------------------------------------

Ave. for 1st 6:   903 fps
                           26   fpe

Extreme spread:  10.7 fps


So in my opinion I think I have my Discovery set pretty good for my hunting purposes.  The first six shots are averaging 903 fps / 26 fpe and I rarely take more than six shots when hunting so this is excellent.  Like I said the POI still doesn't change (at 20 yards) when shooting from 2000psi down to 1000psi, even with the power adjuster, so that is fine.  
What do you guys think?

Brian

[MaineJim]

Hi Brian,well if those 10 shots will do the job for ya go with it i say.
My stock .22 Disco does 855  fps with  30 fps ES  from 1850 psi to 1000 psi
for about 25 shots using CPHPs .
Good luck hunting,Jim.

[preez]

That's way better Brian! Nice gain over stock fps and good consistency. If you're shooting up to 20 yds you can probably go down to low 800's before you see any POI shift. Glad the 75 cent improvement worked out for you.

Chris