John Y Cannuck said:
The 311 recipe is fine, but, like Tiriaq said, this is not going to be anything but plinking amo. Expect poor accuracy, and possible other problems. I doubt you'll see anything serious, as a number of shooters shoot 308 all the time. If it happens you have a tight bore, (it happens, but they are not that common) it may even shoot decently.
In my opinion, the answer is "You won't know how well it shoots until you try it".
It might be thought provoking to open your micrometer or verniers up .0015", or as best you can approximate it. Now hold them up to a light or white colored surface and observe the hairline of light you can see between the anvils. That is the difference around the circumference of a .308 bullet that it is smaller than a .311. In a perfect world...
To really annoy yourself, start miking various makes of bullets... I just trotted into the reloading room and grabbed the first box of .308 and .311 I saw. The Nosler 150 gr. partition .308's miked at .3065" and the .311 Hornady 174 gr. match miked at .3102". And I do have a set of check blocks that confirm my mic has not gone bad on me. Maybe that's why the really competitive guys jump on a given lot of bullets when it shoots well in their competition rifles...
And then there's the fouling that builds up in improperly cleaned (or not cleaned at all) barrels. How much does that reduce groove diameter?
Bill Leeper told me once he won a service rifle match using .308" bullets in his Lee Enfield, just to prove the point. Bill's a fine shot, and I suspect the rifle he was using wasn't exactly a dog, but there you go.
When the heavy Dominion .303 ammunition had dried up, I loaded the Nosler 200 gr. .308 partitions in .303 for a couple of Dad's hunting buddies that figured nothing less than 200 grains was good enough for elk and moose. It didn't shoot supper accurately, but then their old bubba'd .303's didn't shoot that well with .303 ammunition either.
On the other side of the coin, I have a Husqvarna featherweight in 30/06 - the bore slugs .311. I've been reloading and hunting with it for nearly 40 years before I realized I was shooting too-small bullets through it. It did fine all that time that I was using partitions. When I fell in love with the performance of X-bullets, I found out it wouldn't group them worth a damn. It was only then that I slugged the barrel and found out what the real dimensions were. Does the exposed core at the back of the Partition make it easier for the bullet to slug up slightly and get a good launch while the solid X-bullet won't do that? I don't know.
I also have a Model 95 in 30 Government that also slugs at just over .311. I don't know how it does with the jacketed stuff because it gets nothing but cast lead bullets for its' diet. Did the factory accidentally mix up a bunch of barrel blanks intended for .303 British with .308 barrels intended for 30 government and 30/06? Who knows, but my grandfather shot many boxes of Dominion ammo out of that rifle and he always seemed to shoot those old iron sights just fine at the range whenever I was there.
So. Give 'er a try and find out.