Barrel twist rate is not exact. For example, a 1:9 marked barrel might actually be closer to 1:8 or 1:10 (although most newer barrels tend to err on the fast twist side). This, to some extent, explains why a "1:9" twist barrel will stabilize heavier bullets than it is supposed to. A quick and dirty way of measuring the actual twist of a barrel is to shove a cleaning rod with a semi-tight swatch on it down the barrel and measure how many times it turns over a certain length.
The military uses 1:7 because they need to stabilize tracer ammo, but it is actually not an optimal twist rate. It degrades accuracy for 55gr and lighter ammo, and causes excessive drag, reducing muzzle velocity (slightly). 1:9 was a good compromise for civilian shooters because it would work with just about any ammo until the advent of the new heavy bullets (70+gr). 1:8 is popular with precision shooters because it will stabilize the heavier rounds without the excessive drag of 1:7 (I guess for them even a couple of FPS advantage is important).
If you're looking for a good barrel, Nordic Components has 1:8 Wilson stainless mid-length barrels for $179 with free shipping. I doubt you're going to find a better deal on a better barrel. They also have Lilja barrels for $289, which might seem a bit much, but are arguably the best barrels money can buy (although I suspect these are the "budget" non-hand lapped barrels - still excellent barrels for the price).
The military uses 1:7 because they need to stabilize tracer ammo, but it is actually not an optimal twist rate. It degrades accuracy for 55gr and lighter ammo, and causes excessive drag, reducing muzzle velocity (slightly). 1:9 was a good compromise for civilian shooters because it would work with just about any ammo until the advent of the new heavy bullets (70+gr). 1:8 is popular with precision shooters because it will stabilize the heavier rounds without the excessive drag of 1:7 (I guess for them even a couple of FPS advantage is important).
If you're looking for a good barrel, Nordic Components has 1:8 Wilson stainless mid-length barrels for $179 with free shipping. I doubt you're going to find a better deal on a better barrel. They also have Lilja barrels for $289, which might seem a bit much, but are arguably the best barrels money can buy (although I suspect these are the "budget" non-hand lapped barrels - still excellent barrels for the price).
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Thanks, false advertising and/or faulty construction! 
