Cutting down a fluted barrel is fine, just looks a bit funny. To make it look less funny you can chop it then thread the muzzle for a cap or a muzzle device.
I have seen very light barrels with substantial fluting peel right back to the chamber on firing factory ammo. The barrel maker was quite excited about that batch of barrels... This was 25 years ago...
I have also completely exposed the fluting on stainless heavy fluted barrels when shortening them and it worked just fine... if the barrel is of decent weight I would not worry about it.





























