I have mostly shot Open and Hunter classes at AAFTA FT matches. So far my best piston gun for those classes had been a 19fpe Diana 54. The sled system allows for fairly accurate shooting even at 19fpe. I had a good run with the D54 but then sold it to make room to try some others. I tried an LGU for a brief period but it seemed better suited for lower power. I sold that too. Hatsan recently had a sale on the Dominator underlever that I had been eyeing for couple of years. It has a swept volume somewhere between the D54 and the LGU. It was only $160 so I could not resist.
Here is all I've done to it so far:
1) Added a longer adjusting screw to the trigger for more adjustment range.
2) Filled the hollow stock with duct seal and lead shot.
3) Made a thread-on muzzle weight to fit the 1/2-28 threaded barrel.
I was going to open it up to do a lube tune, but after looking at the complex beartrap interlocks and small parts, I decided to leave it as-is for now. It has a decent shot cycle and shoots AA 8.4gr at about 15fpe. I currently have a 4-16x44 UTG SWAT scope installed. After trying a number of different pellets and shooting it for a couple hundred shots, the gun appears to be accurate enough for field target.
I'll be shooting the Dominator in the Open and Hunter piston classes at the AAFTA GP matches. The QB58 will be used at matches where they only offer a 12fpe piston class.
I plan on going to the WFTF world match later this year. My WFTF piston gun (QB58) is done. See here:https://www.gatewaytoairguns.org/GTA/index.php?topic=151000.0