Hatsan at44pa tuning

[Ruipac]

So I have been interested in learning how to tweak the power on the at44pa. Problem is all the posts I have read are for the non pump version and so I'm not sure of the best way of going about it. Does anyone have experience with the pump action variant and if so could you provide some insight and perhaps a few pics too.     

[Ruipac]

Also, would increasing the hammer spring tension make the pump harder to cock because it isn't exactly easy now as is.

[Hobbyman2007]

Increasing the spring tension will add to the pump effort as it is used to both cock and cycle  the magazine. From what I can see in the parts diagram , there is not much gained by mechanical advantage in the pump stroke. I would start by polishing all contact points and linkages then apply some light lubrication . All other mods for the AT44 should apply .

[Ribbonstone]

Tuning and results should be about the same, there is nothing in the way the striker/valve interact that would change that much.

Increasing striker tension would likely increase velocity...also increase the "sweet spot" towards the upper end of allowed pressure, so you might shorten the number of good shots more than seems proportional.

Pump doesn't really have much mechanical leverage (OK...none) so it will make pumping it a bit stiffer, but you pretty much need to work the pump decently hard anyway.

Are a few "quirks" in the pump version.  The pump interlock should work.  Meaning, once pumped but NOT FIRED, you should NOT be able to work the pump again unless that odd little sheet metal latch in front of the trigger is operated to unlock the pump.  Seems that some of them don't lock up the pump like they were designed to (are some adjustments that can be made).

When that pump-lock doesn't work, you may not notice it.  All the linkages, pump handle weight, and the weight of your hand on the pump do a pretty good job of keeping the breech from opening all the way back and causing a breech leak....but what happens is that at the moment of firing, the air pressure bumps the pump handle back a little...which is pretty much like someone bumping the rifle right as the pellet is launched, which generally makes for poor accuracy.

SO...test your pump.  Pump it, do NOT fire it, and see if you can pull that pump back again.  If you can, then the odd pump-lock system needs adjusting.  If you can't, then work that little sheet metal lever ahead of the trigger and see if the pump slides back then (as it should).

[Ruipac]

Thanks, and yep the pump works as it should. It stays locked in the firing position and will only unlock when the lever in front of the trigger is depressed.  I was just unsure if it was the same procedure to adjust the hammer as the side lever model. The pump action isn't that hard to actuate but a firm pull is required to cock it.  I dont mind the performance the way it is but of course my need to tinker with it is slowly getting the best of me. Lol

[Ruipac]

So I looked at the diagram for both the lever action and pump action and they look very different.  Has anyone here actually adjusted the hammer on the pump version? 

[Ribbonstone]

Only adjustment is the striker spring tension, and it works like the other 44's (counter clockwise increases striker spring tension...increases the "sweet spot pressure range"...and generally increase energy at the expense of shot count.



If you want to go faster, then will have to (1) mod the valve  (likely a thinner.better air flow of the valve stem) and (2)

Mine has become a more or less "pure" hunter.  Seldom bother to put it on a bench, use a 4X scope (although it's an old 4XAo version0, and shoot bigger critters inside of 50yards (and the closer the better for my philosophy).



I actually like the pump action, but I was rasided with pump action  shotguns so I'm use to the nearly automatic drill of pumping.  For me, makes a great woods hunter., but if you're looking fore a bi-pod or bench rested super sniper...keep looking,