RE: ballistics question
as myself id say that yes the longer barrel will give you a little bit added velocity but a 243 is primarily a small game and deer round. Win most ppl look to get a varmit gun they want a longer barrel for increased range and stability.
Secondly ive found that remington ammo does foul up your barrel a tad more than other brands. i primarily shoot winchester ammo in my 3006 and 308 for deer season and find that after a shot at the range or field that there is less powder and resedue to be cleaned. But here lately i have found that federal is the worse of the 3 ihave mentioned i always had to keep my 7mag clean after several shots. But again thats my opinion.