I'm looking at shooting a few ftr matches this yr and am wondering if the 308 barrel I currently have will work. It's chambered in 308 but throated for the 178 elds will this be allowed does it have to be chambered to saami spec?
Your chamber is fine, they have no free bore or neck diameter restrictions. I have only had chamber actually checked one time at the 2017 world championships. They only run a standardard 308 go and no go gauge to test chamber. The top level shooters normally are running a .340 tight neck(some) and a minimum of .170 freebore (all).
Here's the current NRA rulebook that includes F-class. I have found most clubs are fairly lenient in allowing non-conforming rifles to participate, but will not send scores to the NRA for recordkeeping. The most common issues are muzzle brakes and rifle weight limits. It's a good idea to contact the match director before participating, more than likely they will help steer you in the right direction.
Have fun when you go!