Crosman 2289g ACP questions.

[DavidS]

I am quite happy with my Crosman 2289g-ACP.   It gives me 3 good shots with reasonable consistency, with just a tad of air left after the third shot.

The trouble is that it is just REASONABLY consistent.

I have no way to directly measure the AirPressure in the valve (I can only estimate by calculating), I have no good way to measure the strength of the springs, and I have given up attempting to measure the valve internal volume.

I have increased the valve volume, verified that there is no issue with hammer bounce, tuned the springs as well as I can, did the standard valve porting, drilled barrel TP, poly tube TP, stuffed the piston, pinned the valve, pinned the check, took up the extra space between valve O-Ring and valve face, shimmed the piston, and made a cam over pop out pump handle pressure indicator.

This 2289g does have an 18 inch barrel and a steel breach.

MY QUESTION IS:
What else can I do to improve the consistency of this 2289g-ACP?

[mav72]

I've seen a pressure guage added to a pumper... Don't know if that's the direction you want to go...

[plinker99]

Hi David,
   I was hoping that other experienced guys would answer you.  Seeing that you may be the only one that has a modded 2289 acp, you're the expert on that one now.
   You asked for ways to make it more consistent.  More specific information is needed.  It's cool that you get 3 shots, but you didn't mention on how many pumps.  Also 3 shots at what fps/fpe & what pellet?  Last, what more consistency are you looking for?

[DavidS]

Hi David,
   I was hoping that other experienced guys would answer you.  Seeing that you may be the only one that has a modded 2289 acp, you're the expert on that one now.
   You asked for ways to make it more consistent.  More specific information is needed.  It's cool that you get 3 shots, but you didn't mention on how many pumps.  Also 3 shots at what fps/fpe & what pellet?  Last, what more consistency are you looking for?

26 pumps, aprox 550fps to 520FPS, aprox 9.6fpe to 8.5FPE, CPHP 14.3 grain.   7 to 8 pumps to recharge after one shot.

Looking at getting the 3 shots closer to equal.

Thank you.

[TimmyMac1]

I am quite happy with my Crosman 2289g-ACP.   It gives me 3 good shots with reasonable consistency, with just a tad of air left after the third shot.

The trouble is that it is just REASONABLY consistent.

I have no way to directly measure the AirPressure in the valve (I can only estimate by calculating), I have no good way to measure the strength of the springs, and I have given up attempting to measure the valve internal volume.

I have increased the valve volume, verified that there is no issue with hammer bounce, tuned the springs as well as I can, did the standard valve porting, drilled barrel TP, poly tube TP, stuffed the piston, pinned the valve, pinned the check, took up the extra space between valve O-Ring and valve face, shimmed the piston, and made a cam over pop out pump handle pressure indicator.

This 2289g does have an 18 inch barrel and a steel breach.

MY QUESTION IS:
What else can I do to improve the consistency of this 2289g-ACP?

When people would leave 8 pumps in a Benjamin for extended Periods it became a ACP. A for Anemic, C for collapsed seal and P for Profit.
Yes it delivers more foot pounds overall from 29 pumps but the problem is it is GUTLESS and inconsistent. ACP's are a bad joke from a BS artist. That is My Opinion. Without a Gage they are completely worthless. Without stronger parts they are taxing the system to death. I deal with heavy users like pest control guys and they want the thing to dump the entire load. They want it to last. If they want gutless they pump less. They need control to be effective and no gage means no control or success.
I would put a Striker spring guide from a 392 in the thing. I would get my gutless from a Smaller transfer port and if you put a Gage on you might have something worth owning.

TimmyMac1

[DavidS]

The thing that I do not get is that my Crosman 66 ACP is a lot more consistent and it is basically the same exact set of modifications.

And I do not see how a cam over pressure indicator is not enough?    I do not understand how knowing the number in PSI would be any more helpful than just being able to consistently reach a given pressure??

[rsterne]

Two shots at very nearly equal velocity is possible, providing you pump to the same pressure every time.... Three shots, properly tuned, will always yield the middle shot faster than the other two, even if you have a lot more volume.... that is simply the nature of a PCP, which is what you are building, just one with a very small reservoir....

Stick to two shots, or pump to the same pressure after every shot.... or make a valve with a MUCH greater volume, pump it to death, and don't try and tune it for too much power.... If you tune it for 5 shots, and only use the center 3, you might get pretty close to what you want....

Bob

[DavidS]

Two shots at very nearly equal velocity is possible, providing you pump to the same pressure every time.... Three shots, properly tuned, will always yield the middle shot faster than the other two, even if you have a lot more volume.... that is simply the nature of a PCP, which is what you are building, just one with a very small reservoir....

Stick to two shots, or pump to the same pressure after every shot.... or make a valve with a MUCH greater volume, pump it to death, and don't try and tune it for too much power.... If you tune it for 5 shots, and only use the center 3, you might get pretty close to what you want....

Bob

Ok thank you.  I had not thought about it from that view.

It does make sense to get it to 5 shots and rely on the center three shots.   

Or maybe go with the two shot set up, and just pump back to pressure after every shot, I will have to think about that.

[DavidS]

I decided to make it a two shot ACP.  and it seems to do well so far.

[rsterne]

I settled on 2 shots @ 600 fps with 14.3 gr. JSB Express on mine, from 19 pumps with a 2100 pump tube and linkage.... stock 14.5" barrel, 5/32" ports, FTP, Disco hammer spring.... The gun maxed out at 765 fps @ 24 pumps.... which is the equivalent of 36 pumps with a 2289 pump....

Bob