.199 freebore is the SAAMI spec chamber so you aren't overly long. Both my custom Creedmoors have that chamber. Loading the 140 ELD-M at .020" off the lands I am at 2.850" OAL and it works great in AICS mags. I wouldn't go to .100 freebore. Too tight and you will have to push that bullet too deep in the case. Go with a .169" if you want shorter as that will put them at 2,820" at about .020" off the lands but I would try to shoot what you have now first.