Hatsan at44 .25 cronie

[Mont]

I had some time to shoot my at44-10 .25 over the cronie yesterday.  This gun has the bob mod using 25.4 JSB's, which shoots very nice.  I found that this gun has a sweet spot at 110-120 bar. The fps start a 770 with a 200 bar fill, slowly dropping until 160 bar.  Then the speed starts creeping up to 850-860 range plateauing at 120 bar. At 120 the speed begins to drop slowly. I also noticed as the psi drops the POI raises.  Peaking at 120 bar, about 1.5" at 50 yards. At 100 bar the poi then starts to drop.  I repeated this test three time with the same results each time, and using the gauge on the scuba tank.  Hoping to insure quality psi readings.
I'm thinking a regulator set at 120 bar may work very good.  What do you think?  Thanks Joe

1st attachment is 150-100 bar test,
2nd 185-100 bar test,

[Rallyshark]

I think you have the right idea.  If it were me, I would set it just slightly higher, like around 125-130 bar for a reg.  You will have a little less air available with with a regulator due to the plenum size.  Chances are your velocity at 120 bar will be a bit less than it is without a regulator at 120 bar.  I like to set my regulators a little higher than the what they need to be, so I still have a little flexibility with the tuning.  I also like to tune my guns on the lower side of the "knee" to get the most efficiency and make them as quiet as possible.  That is just a personal preference really.

This is all assuming you leave the hammer spring setting right where it is.  If you were to increase the pre-load, you'd be getting higher velocities, and your sweet spot would arrive at a higher pressure.  I think a regulator would definitely work great for you at the speed you want to shoot though. 

I say get that regulator and start playing

[Mont]

Thank you, I got my regulator today.  After work, on to home too install my regulator.  I like your advise of 125bar, That make's perfect sense.   I was planning on just try and set the regulator for the lowest psi with the highest fps.  Try and make the air go as far as possible per fill.  The hammer spring will likely get adjusted at some point in the quest for perfection.  Thanks Joe

[Lastcat]

Thank you, I got my regulator today.  After work, on to home too install my regulator.  I like your advise of 125bar, That make's perfect sense.   I was planning on just try and set the regulator for the lowest psi with the highest fps.  Try and make the air go as far as possible per fill.  The hammer spring will likely get adjusted at some point in the quest for perfection.  Thanks Joe

Good to hear Joe, good luck. Look forward to you joining the NUAH Club soon. Post pics. Cheers