Shots per charge on 1720t?

[anuthabubba]

Wondering how many shots per charge you guys get. My second hand one is at the factory setting and I have been able to hit pretty well out to ~30 yards, offhand plinking, for about 40 shots with the Bman SS-2 4x Mini and 10.3gr 'Cuda Hunters. Need to shoot a few strings over the Chrony I guess but pumping it, even with a new Hill Mk4, is NOT EASY! Although a bit easier than with a Benjamin Mk1 pump.

[Motorhead]

40 +/- is pretty typical, tho ES #'s likely to be 4% or more.
Those who regulate them and fiddle with guts can get this same 40 shots tho inside 1 1/2% ES.
* this shooting in the 9-10 ft lb range.

[BigTinBoat]

Wondering how many shots per charge you guys get. My second hand one is at the factory setting and I have been able to hit pretty well out to ~30 yards, offhand plinking, for about 40 shots with the Bman SS-2 4x Mini and 10.3gr 'Cuda Hunters. Need to shoot a few strings over the Chrony I guess but pumping it, even with a new Hill Mk4, is NOT EASY! Although a bit easier than with a Benjamin Mk1 pump.

I think my tune is now at 16FPE and I get 22 or 23 (IIRC) shots w/i 4%

Sounds like something is really wrong with your pump, or pumping "technique". After 20 shots it takes me like 5 pumps to fill hose and then 20 pumps and the gun is back to 3K. I'm about 195lbs and all I have to do is basically "lean" over the handle with my upper body and the stroke is easy.

[anuthabubba]

Wondering how many shots per charge you guys get. My second hand one is at the factory setting and I have been able to hit pretty well out to ~30 yards, offhand plinking, for about 40 shots with the Bman SS-2 4x Mini and 10.3gr 'Cuda Hunters. Need to shoot a few strings over the Chrony I guess but pumping it, even with a new Hill Mk4, is NOT EASY! Although a bit easier than with a Benjamin Mk1 pump.

I think my tune is now at 16FPE and I get 22 or 23 (IIRC) shots w/i 4%

Sounds like something is really wrong with your pump, or pumping "technique". After 20 shots it takes me like 5 pumps to fill hose and then 20 pumps and the gun is back to 3K. I'm about 195lbs and all I have to do is basically "lean" over the handle with my upper body and the stroke is easy.

Please describe a 'proper technique'. If the thing functioned on each stroke it wouldn't take many.

[anuthabubba]

Thanks Scott.

[nervoustrigger]

Yrok, I set up a 1720T for a buddy a few weeks back and unfortunately I did not save a string in stock form but it was producing ~9fpe and I think roughly 40 useable shots.  By useable I mean for close-range pesting (25 yards or so).  I'm rather sure the extreme spread was too poor for 40-50 yard duties.

He wanted it cranked up a bit for field target so I started a bstaley tune loking for a bell curve that topped out just under 12fpe.  I ended up with 34 shots inside 4% with an average energy of 11.4fpe, or a total of 388fpe. 

The total fpe is a decent way of estimating what shot count you might expect at a different tune.  In other words, if you were looking for around 9fpe, you could expect about (388 / 9) = 43 shots.  Maybe a bit more since a downtune improves efficiency somewhat.

FYI, near the top of the yellow right now is a thread about regulating a 1701P.  One of the replies is from someone who put a regulator in a 1720T and he ended up with almost the exact same total fpe per fill.  Not sure what ES he was getting; he didn't say.  Presumably it was better than 4% but seeing as how 4% is considered good enough for 50 yards, from my perspective there's no difference in practice.  What I mean is, I'm not reaching for the 1720T for 75 yard shots.  There are better tools for the job.

[Motorhead]

FYI, near the top of the yellow right now is a thread about regulating a 1701P.  One of the replies is from someone who put a regulator in a 1720T and he ended up with almost the exact same total fpe per fill.  Not sure what ES he was getting; he didn't say.  Presumably it was better than 4% but seeing as how 4% is considered good enough for 50 yards

That was me within that thread with the long tube 1701P .... all @ 42 shots inside 1 1/2% ES.
It took a Light hammer increasing hammer strike speed also giving lower valve dwell to stabilize that tune.

[nervoustrigger]

Haha, that Scott!  THE Scott

Sorry man, I didn't recognize you!

[Motorhead]

Haha, that Scott!  THE Scott

Sorry man, I didn't recognize you!

Lol ... so many ways in getting to the same place.  needless to say I'm regulator biased 

[BigTinBoat]

Please describe a 'proper technique'. If the thing functioned on each stroke it wouldn't take many.

Well describing in words might be a bit of a task. So I'll use google images to help.

1) Raise pump handle all the way and hesitate for just a second to allow the outer stage to fill. Then on the down stroke steady and slow as you raise over top of the handle as the resistance gets greater. To overcome the resistance with the least amount of work you want to "balance" your body weight over the top of the handle, and come up off the soles of your feet. Kinda like if you were balancing yourself on the top rail of a fence like the below pic. Your dead weight will then dramatically aid in overcoming the pump resistance without you exerting much additional force. Pause for just a second at the bottom and then slowly raise all the way to top and repeat until gauge reads 3K. My 1720 shooting at 16fpe takes just about 1 pump per shot.


that's about the best way I can describe it

[anuthabubba]

Thanks Rob. But the check valve is not functioning properly and does not allow air intake on the upstroke consistently. When it does, it is nice and builds pressure in the airgun rapidly. Burns my boo-tee to get a new $300 pump that won't work as advertized. "Oh, you can return it for replacement." Yeah and pay 2 way shipping!?!? To Ohio or England! No thanks! Guess I'll have to take apart the brand new POS and fix it! Might be more forgiving of this kinda crapola from the cheaper B pump which actually didn't work any worse!

[BigTinBoat]

Thanks Rob. But the check valve is not functioning properly and does not allow air intake on the upstroke consistently. When it does, it is nice and builds pressure in the airgun rapidly. Burns my boo-tee to get a new $300 pump that won't work as advertized. "Oh, you can return it for replacement." Yeah and pay 2 way shipping!?!? To Ohio or England! No thanks! Guess I'll have to take apart the brand new POS and fix it! Might be more forgiving of this kinda crapola from the cheaper B pump which actually didn't work any worse!

Might not be the check valve. I think some pumps got out recently with the wrong o-ring in the 1st stage. See the below post. Pay attention to the reply by robertr - sounds like exactly your problem. Should be a simple fix

http://www.gatewaytoairguns.org/GTA/index.php?topic=92945.0

[anuthabubba]

Did a bit of tweaking on my 1701p and 1720t pistols this afternoon. Was able to slightly increase the fps and consistency of shots/fill on the 1701p (50@470-490fps w/8.4gr) and the 1720t (40@615-640fps w/10.3gr). Not after BIG power, just good/consistent power and shot count. Made a 30 yard offhand headshot yesterday with the (no buttstock) 1720t. Have rifles for the higher power requirements.

[anuthabubba]

Thanks Rob. But the check valve is not functioning properly and does not allow air intake on the upstroke consistently. When it does, it is nice and builds pressure in the airgun rapidly. Burns my boo-tee to get a new $300 pump that won't work as advertized. "Oh, you can return it for replacement." Yeah and pay 2 way shipping!?!? To Ohio or England! No thanks! Guess I'll have to take apart the brand new POS and fix it! Might be more forgiving of this kinda crapola from the cheaper B pump which actually didn't work any worse!

Might not be the check valve. I think some pumps got out recently with the wrong o-ring in the 1st stage. See the below post. Pay attention to the reply by robertr - sounds like exactly your problem. Should be a simple fix

http://www.gatewaytoairguns.org/GTA/index.php?topic=92945.0

Thanks Rob. Guess I'll need to find that O-ring and an exploded view.