Does anybody offer a 270cal. in an AR platform ?
there are some custom long action AR type rifles that have been built , often in 300 win mag but they are all custom
also understand that the AR 10 platform 308 / 7.62x51 have a few different patterns and you need to know what pattern you are working with gen 1 gen 2 manufactures have their own.
the AR15 being mill spec all the parts fit together there isn't near the issue of what generation it is.
so lets say you want to get a 130gr bullet of approximately 277 to about 2950 fps maybe it would make a lot more sense to go short action AR 10 save a thousand dollars or more to go 7mm-08 .284 yes your going to give up about a 100 fps with the short action but that only changes a 200 yard zero about an inch an a half at 400 yards.
when you have to buy a custom gun at $2500 or more with 100 dollar mag vs a production $1000 gun with 15 dollar mag , 100 fps and 1.5 inches at 400 yards gets easier to take if you are willing to get a little more main stream you can have a 750 dollar gun in 308 you will have to give up 3.5 inches at 400 yards although because it is a heavier bullet your still only giving up 3.5 inches at 500 yards where the lighter bullet starts falling faster.