Should I just get a regulator ?

[Jfrench]

I have my at44 shooting much better groups now .
The barracuda hunters are working pretty good out of it and I now have a chrono to work on it .   here's what I'm getting.

Created: 02-19-2016 10:22:47
Description: barracuda hunter
Notes 1:
Notes 2:
Distance to Chrono (FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 18.210
Temp: N/A
BP: N/A
Shots
#     FPS        FT-LBS     PF
27    918        34.08      16.72    
26    928        34.83      16.90    
25    931        35.05      16.95    
24    953        36.73      17.35    
23    ERROR 2
22    957        37.04      17.43    
21    942        35.89      17.15    
20    927        34.75      16.88    
19    932        35.13      16.97    
18    ERROR 3
17    916        33.93      16.68    
16    911        33.56      16.59    
15    916        33.93      16.68    
14    914        33.78      16.64    
13    895        32.39      16.30    
12    903        32.98      16.44    
11    882        31.46      16.06    
10    894        32.32      16.28    
9     891        32.11      16.23    
8     ERROR 3
7     881        31.39      16.04    
6     865        30.26      15.75    
5     866        30.33      15.77    
4     866        30.33      15.77    
3     858        29.77      15.62    
2     849        29.15      15.46    
1     853        29.43      15.53    
Average: 902.00
StdDev: 31.84
Min: 849
Max: 957
Spread: 108
True MV: 902.10
Shots/sec: 0.08
Group Size (IN): 0.00

This was from 190 bar to 140
Was also 3 other shots not showing ( birds landed close by )     

[rsterne]

You need to either reduce your fill pressure (fewer shots), or increase the hammer spring preload (more power, fewer shots).... the velocity at the beginning of the string is much too low compared to the peak.... I recommend a 4% ES.... If you install a regulator set to 140 bar, with a large enough plenum, you should be able to get just over 900 fps with consistent velocity....

Bob

[Jfrench]

Thanks Bob,
I'll back the power screw out another turn and see what it does .
That's the right way isn't it ?

[LDP]

Thanks Bob,
I'll back the power screw out another turn and see what it does .
That's the right way isn't it ?

Yes.

[Jfrench]

This is what it got now
Created: 02-19-2016 15:18:43
Description: barracuda huntets
Notes 1:
Notes 2:
Distance to Chrono (FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 18.210
Temp: N/A
BP: N/A
Shots
#     FPS        FT-LBS     PF
20    ERROR 3
19    935        35.35      17.03     
18    919        34.16      16.73     
17    955        36.88      17.39     
16    942        35.89      17.15     
15    938        35.58      17.08     
14    921        34.30      16.77     
13    921        34.30      16.77     
12    932        35.13      16.97     
11    941        35.81      17.14     
10    942        35.89      17.15     
9     935        35.35      17.03     
8     932        35.13      16.97     
7     937        35.51      17.06     
6     925        34.60      16.84     
5     923        34.45      16.81     
4     910        33.49      16.57     
3     924        34.53      16.83     
2     897        32.54      16.33     
1     ERROR 2
Average: 929.39
StdDev: 13.46
Min: 897
Max: 955
Spread: 58
True MV: 929.49
Shots/sec: 0.03
Group Size (IN): 0.00
 But this time I filled to 200,  I'm thinking 180 to 190 might be better ?
I'd still get 20 good shots .

[Jfrench]

I have one more question ?
When I read about regulator instals they say use fast fill .
All I have is a pump . will I not be able to use it to fill ?

[Rallyshark]

I have one more question ?
When I read about regulator instals they say use fast fill .
All I have is a pump . will I not be able to use it to fill ?

Finally, an airgun question I have a lot of experience with!    You CAN do it with a pump.  I've don't it many times.  You will have to pump really fast on the down stroke to get the air in fast enough for it to seal.  You may have to shorten the up stroke too, just depends on if you can hear it pulling air from the cylinder on the up stroke.  I've done it with a Benji pump, and a Hill mk4.  It is easier with the Hill, since it moves more air.  It is a workout, but once you get it to seal, you're good

Is your AT-44 a long?  I was getting 35 shots at 35fpe with mine with a reg.  That was with a 200bar fill, and I could get 40 shots if I filled to 205bar.  Granted, I did the valve mod(down to the valve pin seal), and opened the barrel and transfer ports a bit.  I can get right at 50 shots at 30fpe, which is where it is now.  I have my reg at 120 bar right now.  It will actually do 900fps with the H&N BHE19.09 with the reg at 110 bar, but it isn't as efficient.  If your gun isn't modified, then you probably will need the reg set at 140+ bar.  I'm not positive, but I think I was getting maybe 25-27 shots with it un-modded?

[Iamscotticus]

Can a Benji pump last very long?  Will it get hot?

[Rallyshark]

It isn't that hard on it to get the reg to seal.  You only have to pump fast for a short period of time.  Once it seals, you can stop and let the pump cool down.  I was always able to stop at less than 50 bar.  I did kill my Benji pump, but it was due to moisture getting in it/no desiccant filter.  I will never own another pump without a desiccant filter.  One can be added to the Benji though.