How much quicker will using a fast twist cause a barrel's throat to be eroded? I'm contemplating a fast twist .224" (1:8") and wondered it that will mean that I have a barrel eater on my hands??

More info is needed, a barrel on a 223 is alot different than one on a 22/6mm.

Depends on how much powder you are pushing, etc.

Specifically, I'm looking at a .223 AI (I'm guessing will max out around 33gr of WW748 or equivalent speed of powder.

I'm not really looking to get extreme velocity, but it would be nice to get 2500-2600fps with a 80gr bullet.

From everything that I have read, there is no measurable difference in chamber pressures, velocities, or barrel life between twist rates. The only concern with twist rate is to select the appropriate rate necessary to stabilize the bullet. Over stabilized bullets keyhole at distance and under stabilized bullets being to yaw and ultimately tumble at distance. Unless you are shooting well past 100 yards, you will not generally see much difference in over stabilized bullets (within reason).

Here is a very good link for exterior ballistics - http://www.nennstiel-ruprecht.de/bullfly/index.htm

Somehow Ruger put a 1-10 twist barrel on my 7mm Mag #1 that I got in 1969. I shot it a lot and then it would not stablilize the 160 gr Sierra BT. That's when I discovered that the twist was not 1-9.5 as it should be.

Once your slow twist barrel gets worn it may not stabilize long bullets. Go with the 1-8 or faster.

It's a old story now but worn 30/30's shoot OK and 32 Specials with the slower twist don't.

Two powders you may want to try that give good results in 223 are varget and reloder 15.

The barrel life for that round should not be of any real concern. It should last quite some time but you might want to shoot molly to prolong it even more.

I have never seen any scientific data on it affecting throat life one way or the other. But I can tell you this, I've had a few friends who built rifles with abnormally fast or slow twists and all of them ended up very sorry they did.

Essentially what you are doing is robbing your rifle of a lot of it's versatility. Everyone thinks they won't care...but turns out they do care a lot. And when it comes time to trade it they usually end up taking another beating.

Like building a dragster. It might be great for quarter mile racing...now drive across town and pick up the kids or get a quart of milk at the 7/11. It sucks for that.

Don't paint yourself into a corner is my advice.

I would think that the answer to this question would be more a matter of barrel quality than other elements.

Pecos45 - I'm hardly doing anything "non-standard" as many people are using 1-8" Armalite and similar type rifles chambered for .223 in long range competition. My specific purpose differs in that I'm using a contender in silhouette competition. Versatility is hardly a concern. I agree that I might not be able to sell it for the money, but I suspect if I have some success with in the the silhouette game then there will be people who want a similar type setup! Anyway it is a foregone conclusion regarding my decision. I just wanted to find out if barrels tended to wear out faster with a quick twist as compared to a 1-12" or 1-14". I still suspect that barrel life will be somewhat less, but without much evidence I also conclude that it probably isn't bad enough to worry about.

B - I read an article last night by a chap with considerable experience evaluating barrel life for the military and his conclusion was the worst enemy to barrel life was "flame temp." Which he said goes hand in hand with HIGH pressure. You can't have one without the other tagging along.

I stand corrected about many current .224 bore rifles using a twist as fast as you propose, sir.
Forgive me, sometimes I date myself as I think in my time 1/16 or 1/14 was considered about right for the .224 caliber.