I think it's a workable idea, but for more insight, I'd go back and re-read everything Ken Waters has written in Pet Loads about the 30-30, the 308, and the 30/06.
He claimed that most 150-grain factory 30-30 loads ran about 2,200 fps, and that most 170-grain factory 30-30 loads ran about 2,000 fps, which is ~200 fps lower than advertised. He also said that if you load the 30-30 to published velocity, that the bullets expand quite a bit more.
In one of his Pet Loads columns on the 30/06, he mentioned a factory load from one of the Scandinavian countries that they call the 30-30/06, which does pretty much what you're talking about. I see no reason that the same idea wouldn't work in a 308, especially in a carbine that you're purposefully loading down a little. I'd tend to stick with RN bullets over FNs to make sure that they don't hang up on the feed ramp.
FWIW, I've used H4895 to load 30-30 bullets at reduced velocity in the 30/06 for years, at first because they were cheap and then because I needed a load for my son that didn't kick too hard. I also loaded up a bunch for a buddy to teach his wife to shoot with a Savage 99 in 308. Loads in both calibers were accurate and didn't kick much, but we never killed anything with them.
Okie John
