Just got my CH dies in and trying to set them up for the new unfired rifle and she won't chamber a case. FL dies are turned all the way in to the shell holder base...Tried to chamber the 7-08 sized brass in 2 different .308s with no problem. I FL sized a .308 shell in a Lee FL sizer, cut off the neck and it won't chamber in the X-bolt either. Nope, I don't have any factory ammo (haven't shot factory in any rifle for 15 years)so can't test that. Some 7-08 I loaded in RCBS dies years ago won't chamber either. Even if factory ammo chambers there is clearly something wrong with this if I can't reload for it. It goes back to the dealer Monday and I hope I can get a refund.
Anyone ever hear of such a thing before?

Before I went for a refund I would prove it could not chamber a factory round. Otherwise you don't have a valid complaint and most will not refund your money you are are on great terms of the owner of the shop who sold you the rifle.
Shouldn't the owner of the shop have factory ammo around?

You need to prove the rifle will not chamber factory ammo to prove it has a bad chamber

This will be a good one to follow........

If you are not putting a bullet in the case and feeding the case thru the magazine, I have seen some rifles that will not accept the case head into the bolt recess by just dropping the case into the chamber. This effectively makes the case length too long and the bolt won't close.

This ^^^^^^ Had a Win M70 that had been rebarreled. Tried to chamber a 1x, resized dummy round to check COAL with a particular bullet. Stuck the case in the chamber. Same dummy round chambered no problem in both a Rem 700 and a Sako. Turned out that the 'smith who rebarreled the rifle cut a minimum spec chamber. Factory cartridges, hand loads with new virgin brass, and snap caps all chambered properly. But 1x brass would not chamber unless resized with small base dies.

I would not expect a factory rifle to have a minimum spec chamber. But, stranger things have happened.

There may also be a BATFE issue with the store owner taking a rifle back. Since it's been registered as your rifle, he could insist you have to send it back to Browning for repair.

New or used brass? I just built a 6mmbr and it won't chamber my brass even when resized from my other 6mmbr. Too bad you don't have a bore scope. I would think its an ammo issue not the rifle. I have an Xbolt in 7mmwsm.

Thanks for the suggestions, they are spot on.
I think I can answer my own question now after more research. This is common problem with custom target chambers that are built tight to spec apparently. I polished a shellholder surface slowly by hand and kept trying to size the brass and chamber it. Took a while but I now have it working perfectly for a nice 'crush fit' of any brass I tried, .308, .243. or 7-08 R-P and FC. I wish I had thought to measure the base before I started to see how much I took off but it now is clearly labelled and will only go with those dies for that rifle. This should be a good shooter and there is some truth to Brownings claim that all barrels are hand chambered to precision target tolerances. Have some ladder loads made up and can't wait to try it.