HatsanAT44 (H) Class Regulator, One Size, Black

I installed two of these regulators in my two cylinders for my Hatsan Bullboss .25. I was able to adjust both so that they were within 4 fps of each other on average. Shooting 33.95 grain JSB King Heavy pellets, one cylinder averages 767 fps and the other 763 fps. I get 18 quality shots from each cylinder. Spread within the 18 shots is 23 fps for both cylinders. Now to move on to lighter pellets to see what kind of results I get there. So far, I'm pleased.

Works well, but Hats an needs to update the installation instructions on their website. Mine did not have any external O-rings on the regulator, as pictured. If this is the case with yours, DO NOT remove the large ring on the valve unit. If you do, the cylinder will not hold air... don't ask how I know.Installation was, however, easy and it functioned very well. Before, using 18 grain pellets my gun was starting at 870 fps, climbed to about 890 and fell to around 690 by the 40th shot and bottom of the green on the air gauge. Following installation, the first 33 shots were all clustered around 860. The next 7 slowly declined, but never fell below 820. I am, therefore, getting the same number of shots but most are nearly identical in power and the bottom is far better than the last shots before the regulator.

Awesome product

This product is absolute crap. Buy a huma regulator.

First the GOOD:+Price...+ The regulator made my crappy .177 Bullboss useable! Before the regulator, after a fill, my Bullboss would have 4 supersonic shots, then a good group, then the rest were useless non grouping shots.+++ Now with the factory regulator setting, the Bullboss 177 will do two 10.6gr pellet magazines in the +/- 930fps range with reasonable groups.The BAD:- No instructions and the Hatsan online information is for a different designs. The one I received, doesn't have a second "o" ring like the online Hatsan PDF.- The video online is also for a different design valve.- In addition, with the one I received, if I followed the Hatsan installation PDF and removed the valve main tube "o" ring it wouldn't have functional at all.Bottomline, if you are some who is cheap and likes to tinker then buy this and take your chances you can make it work on your gunBut, if want instructions, and accurate how to YouTube videos. Buy one of a more expensive regulators and a better gun than the too heavy, clunky Hatsan Bullboss.

I have 3 of these regulators. This one was the last one I purchased. My gun seemed to run out of breath after the first shot. It was like the plenum could not fill. I ended up returning this one, Out of my other 2 one has been fantastic and the other needed taken apart and worked on. The regulator now functions as it should. These regs were installed Hatsan air rifles. YMMV

Seems to be effective easy enough to install. I get 36 shots of consistent power out of my .25 bullboss with this in it.

This regulator did not fit in a Hatsan Bullboss. Maybe they send me the wrong one,because the item that I received looks different than the one in the picture. It looks very similar but did not have O-ring. I tried to screwed the regulator in but the thread did not fit also. I had to return it back to Amazon.