A little disclosure after looking at my post.... it did not violate the overall length. The issue was a 15" max. length rule for the barrel including attachments. I think it was about a half inch too long or perhaps a little longer than that but less than an inch IIRC. Once the moderator was cut, I discovered that the shorter moderator bumped up the power to about 15 ft lbs. After about a tin of pellets, the epoxy that the machinist used to glue in the end cap let go and my end cap went flying out of my yard. I could not find it but the tube was a smooth ID. I shipped it to another machinist in Colorado that I knew that said he could fix it with a real high grade epoxy and he machined a new end cap for me with a groove in the end cap and he put it back together. He said that epoxy that he used would not let go. Still going strong a few years later.
For the tuning, I had a tough time finding anyone that had any experience with the HW44. I understand it is somewhat complex to tune. I dont think that person does it anymore so I can't help with a tuner to get you under 12 ft lbs. I think if I shot 7.33 pellets I could get just under 12 ft lbs when new. But I wanted to shoot the 10.34 since they shoot lights out. Once you shorten the moderator, I doubt that you wull get under 12 ft lbs, even with 7.33 pellets. You will just have to try to see who you can find. I know I tried motorhead and a few other good tuners on AGN but struck out finding anyone willing to give it a try.
I could suggest that if you bought a new pistol that the dealer may be able to perform those modifications for you to meet the rules. Not sure if they will but they may be willing to for the sale! I am sure it will cost you a couple hundred dollars extra on top of the new cost.
I wish you the best on your journey and glad to answer any questions that I can but as I mentioned I shipped it out for the modifications so I cant help much with how to do it. It would be nice if HW would redesign the HW44 so you can compete right out of the box!
P.S. Let me know if you find someone to detune the HW44 as I need to have mine resealed as it just started to lose air overnight.
Thx
Dan