Does it make sense to regulate a AT-P2?

[sactargetshooter]

I have a .177 Hatsan AT-P2. Currently, it is shooting about 20 shots at close to 12 FPE. The ES is about 20 FPS, mean is 780 FPS using JSB Express 7.9.

Given the small 50cc air tube, does it even make sense to regulate it? My main objective is to increase shot count, then to lower the ES. I can live with an ES of 20 FPS (+/- 10 around the mean).

Thanks for all the posts regarding regulators! I learned a bit just lurking around .

[Mod90]

Makes no sense to regulate that gun. It's such a small reservoir by the time you put in a reg & plenum there's gonna be hardly any room left for air, & that it if you can get a reg to fit it.

Easier to tune the valve. Block off the excess holes in the valve that don't line up with the transfer port, that'll help with the air consumption. And if you can,  remove valve spring seat on the valve body & add a small washer to the valve stem, make sure there's at least a 2--2.5mm clearance of the washer from the inside of the valve body & that it fits the valve stem properly. After that all that's left is to adjust the the hammer spring setting to get it where you want.
I did those mods to my BT65, & it had the effect of lowering the ES from 47 fps down to 10fps, & greatly increased to shot count as well

[rjorge]

After mods, maybe. If you want to regulate it, you need to be able to reach your target FPE at the lowest pressure possible. Let's just say you can reach 780 fps with 7.9gr pellets @ 1500 psi. The plenum + reg will take ~20cc, this leaves you 30 cc as your reservoir size. At a conservative efficiency of 1.3 FPE/ci you will get ~22 shots from 2900 psi to 1500 psi. If you can reach your target FPE at a lower pressure, you will get more shots. Not a drop in mod for sure though...

Check out the Edgun Veles, it's regulated. http://nzairgun.com/forum/index.php?topic=812.0

[sactargetshooter]

Thanks for the replies!

The firing valve already has some mods, and spring set back all the way. Specifically, I put set screws on 5 of the 6 holes except for the one facing the transfer port. I have not filled the groove with epoxy to save some volume, however. The remaining exhaust port is also not much bigger than the original, so that can be improved as well.

I am ignorant to the effects of the valve spring seat/stem mod. What does that do to the firing cycle? A picture will be much appreciated, as well!

The gun currently shoots with a good string (for a non-regulated gun) from 185 bars down to about 110 bars. Filling to 200 bars is a waste because that is before the flat part of the curve. So there is that little bit of extra energy stored in the cylinder if the gun gets regulated.

The AT-P2 uses essentially the same (but shorter) components of the AT44 platform. I think any regulator for the AT44 will also work on the AT-P2. However, the difference, as rjorge and Mod90 pointed out, is the ratio of volume left in the cylinder versus the part taken up by the regulator and plenum.

Maybe I should open up the firing valve body and see what can be done there...

[Motorhead]

Tak,
Agree that with such a minimal tank, spaced used to regulate is too high 

[sactargetshooter]

Thanks, Scott. I suspected as much.

The little gun (midget version of the AT44) does shoot okay for what it is. The short 10" barrel and .177 caliber both contribute to the lack of efficiency. However, for what I use it for, 20 shots (2 magazines) is more than sufficient. I'll just leave it alone since it is shooting well for 20 shots.

[AlanB]

I have a question? 
Been Looking for a left handed action gun....
could this platform be used to add the standard at44 barrel and air tube , stock etc and have a 'Lefty' at44??

[sactargetshooter]

I don't know exactly, but the barrel and air tube both seem to be compatible with the AT44 platform. However, the stock does not have provision to support a long air tube or barrel properly. I think Hatsan does sell a left hand version of the grip. You should check with Hatsan USA though.