If I'm not mistaken, the 1:9 twist rate was picked by the military specifically to stabilize the 55 grain bullet. There just isn't enough difference between the two rates to make a significant difference. Of course you've already been told that.

Neither of these guns is a precision tool. You should expect about 1.5MOA accuracy. The military expects them to be effective out to 500 meters. That's a 4.5" group at 300 yards. The USAF uses a 300 meter zero. The Marines practice at 500 meters with iron sights.

The one big difference is the warranty. I'm sure the Ruger has a good warranty, but S&W customer service has a proven track record. I'd pick the M&P if only for that reason.

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