Not all bllets are gonna' work in the AR15 platform. The best choice is in a bolt gun where you're not limited by mag length and the chamber can be throated to your liking.A question to you 6x45 peeps, I was gunna do one of these but after doing a mock up with a 70 nolser BT in a case and getting it to fit in a 2.260 AOL the ogive of the bullet was in the case neck. Is there something im missing as to way ya would do one?? Are you shooting way lighter bullets? I didnt try long bearing surface short nose bullets like hornady Vmax's but was discouraged with my finding and ended up with the conclusion a 6-6.8 made more sence but finally ended up with a 6WOA in the works as I speak.