Well, if the gunsmith has proof that the buyer asked for a longer than Sami throat, he would be all set. Somehow I find that very hard to believe though. Many people who have a smith build there gun wouldn't know what a SAMI throat looked like. All the prefit barrels being made out there will have a standard throat dimension unless specifically stated otherwise.
There are plenty people on this forum claiming that you can shoot heavy Berger bullets from their 1:10 barrels, but I chose to believe Berger when they say it needs a 1:8 twist or that it is simply better to be conservative and get "more" twist than you absolutely need so that one is never working with marginal stability.
What kills me about this whole discussion is that factory barrels are available with a 1:9 twist so Greg could have avoided the entire custom rifle
thing by just choosing a suitable starting rifle and would have saved a ton of money too. Then when he found that the 1:9 twist was not working for him, he could have gone to a lighter bullet, or what he needs to do now, re-barrel with a 1:8. Buyer beware of shelling out a lot of money on a custom gun based on advice received on the internet. Take a look at what kinds of match barrels are actually selling for your caliber. In 243 it is the 8 twist because of the fact that you can't get one from the factory. Read 6mmBR to see what competition shooters are using. You won't find anyone listed there shooting a 1:0 or 1:9 barrel except for varmints with light bullets, but you will find 1:8 and 1:7.5 for shooting the 115gr DTACS. Be guided by people getting verified results, not internet jocks like me....