Average Valve Output Pressure=Valve OUT Beg+Valve OUT End/2/PM file

[TimmyMac1]

Hi there

Quick question. I bought a At44 long.22 and came with 1000fps from hatsan.soon I install the regulator( 115 bar) I refill the cylinder and the first shot was 813fps without doing any adjustment in the hammer spring. Is that normal? Why I’m having this abruptly change in. Fps? Is because the regulator is taking space inside the cylinder? Or is because the regulator being set up @115bar? I would like to increase the velocity to between 860 -890 is that possible having the regulator set a 115?

Happy holidays
Thanks

The pressure/volume after reg is your total firing volume & that is going to plummet during the firing cycle. Regs won't pass more air during the shot. If there is more space between the reg and valve you would see higher average valve output pressure as the Average pressure would increase dramatically. 115 to 10 Bar is average 55 Bar. 115 to 75 bar is average 85 Bar. Regs take up space but what takes more space is the Firing volume after reg so your average input and output for the valve is greater. I'd shoot for 875 FPS when I want to set records like the AZ EXTREME BR Top Target at 75 Yards(239/8X). 1000 fps is STUPID! We are pushing drag stabilized aero shapes. They don't want to go 1000. You want to go faster and I understand the I want More thing. It says get more lead in your pellet if your going faster than 875. Pellet shooting isn't a Drag Race. If you avoid HIGH DRAG speeds you will make much better POWER & GROUPS DOWNRANGE. We must honor the Physical limits of the drag stabilized projectal.

TimmyMac1

[Tucobenedicto]

Your rifle is designed to work unregulated,the valve see full tank pressure in that condition and the hammer spring is designed accordly.Switching to regulated a certain amount of speed loss is normal,if you are able to increase the section of the air flow path from valve to barrell you can regain some,otherwise the only way is to increase the regulator setting,say to 125-130 Bar,it depends by the volume of the plenum of regulated air available for the shoot cycle.
Next step is to reduce hammer spring force a bit under the obtained awerage speed to avoid air wasting.
All that generally speaking,i don't own an AT44.

[rsterne]

Tim's got it 100% correct, we call the volume downstream of the regulator, that is available for the shot, the plenum.... If you can, try and have a plenum volume of 1 cc for each FPE you want the gun to shoot, and not less than 1/2 cc per FPE.... This avoids (or limits) excessive pressure drop, which hurts both the velocity and the efficiency of regulated PCPs....

His advice about 875 fps is good as well, because that puts the pellet in the "sweet spot" where wind drift is the least for most of its travel to the target.... Driving the pellet at 1000 fps will just result in that extra velocity disappearing in the first few yards anyway, plus it takes a lot more air to get it there in the first place....

Bob

[KnifeMaker]

Thanks for coming around TimmyMac!

Great to hear from you.

Knife