I've been on JPs site, playing around with the rifle builder and have a couple questions for the experts here....I plan on using the Gen 2 UBR and will shoot un suppressed for the most part. I do have a TB Ultra 9 30 caliber suppressor I may run every now and then but not steadily. I'm a little confused as to which bolt carrier and buffer system to order. I assume I would want the low mass carrier and maybe the regular captured spring buffer for reduced recoil and the full mass carrier and heavier captured spring would be best if I run the suppressor???? BTW, I did send an email to JP with these same questions. Obviously they are BUSY. LOL