Re: 22 Cheetah
I know nothing about the 28 degree. But 6mmbr.com shows the 243AI at 2.045". I'd guess that you'd be ok at that trim length. You'd be best served to check with whoever smithed it for you. As far as loading, we need more info. What bullets, twist, and other...
Mine, which is a 40 degree shoulder, like RL22 and 90gr vld's.