I've got a Tac Sol LT upper that's in almost new condition. I put about 50 rounds through it just to make sure it'd work with my lower (it did). Had a hard time deciding which version I wanted and decided on the LT because it's supposed to be more accurate but now I'd rather have something that more closely matches the weight of my regular upper for training purposes. I guess they don't call it the LT for nothing. If someone has a Tac Sol M4 upper in similar condition (around 500 rounds) we can just trade straight across....we can keep our own bolts and magazines, just swap the uppers.