I am having a 264 win mag custom built by hart.it will have #5 douglas taper 27" fluted barrel-jewell trigger-spiral fluted bolt-mcmillan htg stock and a few more options.problem is it is built on an ultra mag action so I dont know how far out to seat my bullets?I can hang out as far as I want with this action,the smith told me to load a dummy round and send it to him he would build around that.I want to shoot 140 bergers and I have allready loaded 78&79 gr of hodgen us 869 up in some new nosler brass and seated the bullets to 3.450 which will easily fit in the magazine but they look awfully long.anyone have any ideas?