I built a 243AI last spring and so far so good. It is a bit of pain in the ass to do all the fireforming, but what i did was try to find a load w/ 80 gr BT's to do my fireforming. This let me find something that would shoot for prairie dogs and such. I then had about 100 rds of fireformed brass ready for 107 SMK's. Finally got a load right around 3200 fps with the 107's.
One other thing is, w/ the 107's, i have them right in the lands, and it makes it a single shot because of feeding issues. I have shortened them, but accuracy goes down as well.
Mine has a #4 Douglass contour barrel and my next one will be heavier as that thing gets smokin' hot after about 10 rds in 10 minutes!!
Sorry for the rambling, but those are the only two issues you might have.
I love mine!! So far I have about 350 rounds through it.
Member - 7STW Club