To answer your question, Yes you can regulate a Hatson Bullboss. It has the same receiver as the AT44. If you want any speeds over 850fps you'll need to drill open the pop valve some. You can expect to get 30-40 regulated shots per fill in .22 or 25. I have one Hatson AT44 in .177 getting 75 shots per fill. Tuned at 810FPS. One thing to remember. The guns that are originally non regulated use other methods to manage the air flow. On this gun the valve is sized small to restrict the air in a manner to limit the flow, This restriction and the hammer spring is used to manage the bell curve as flat as possible. 2nd thing to know, because the the hammer is used to open a valve with a full 200bar behind it. The spring and hammer are to heavy for a regulated gun. Now not to worry you, the spring is adjustable. And you may even want to remove some weight off the hammer latter in your tuning. To adjust the hammer on this gun you'll need to remove the gun from the stock. Use something like a small Allen key to hold the hammer from rotating. By placing the pin from under the bottom of the breach into the hammer bore, into the small hole on the hammer. Then from the rear you need a long Allen to reach the hammer to adjust the spring tension nut, located about 4 inch's in. I'm sorry I can't remember the size of Allen you'll need. My best guess would be a 3mm or 4mm. Clock wise removes spring tension and counter clock wise adds. Yes, it opposite of what you think.
I've personal done this to 5 different Hatson's guns and would recommend it. The Hatson's can be great shooter's with the right tuning and a small amount of love. I used most brands of regulators, personally would recommend using the Lane regulator. FYI, I had one tank, I had to polish the inside of the tank for the first three inches to get the o-ring's to seal. Some of the tanks have a small ridge running the length of inside that needs to polish off. It wasn't hard, I used a fine grit flapper wheel and drill.
Mont
