Kahr MK9 Speer 9mm Performance

[Yogi 117]

Stupid question: would the octagonal rifling possibly affect these calculations for a Glock? I know the PM9 has polygonal rifiling, but just didn't know if the type of rifling made much of a difference when using a chrono, especially in a short barreled pistol.

I know Polygonal is preferred by some ballistic experts. I found this after searching for a reasonable explanation, which answers your question better than I could ever do. I really don't think the type of barreling will have any significant difference in velocity with a 3" or 3.46" barrel. I, for one, would not care which type of barrel I was using. Hope this helps.

A number of advantages are claimed by the supporters of polygonal rifling. These include:

• Not compromising the barrel's thickness in the area of each groove as with traditional rifling.
• Providing a better gas seal around the projectile as polygonal bores tend to have a slightly smaller bore area, which translates into more efficient use of the combustion gases trapped behind the bullet, slightly greater (consistency in) muzzle velocities and slightly increased accuracy.
• Less bullet deformation, resulting in reduced drag on the bullet when traveling through the barrel which helps to increase muzzle velocity.
• Reduced buildup of copper or lead within the barrel which results in easier maintenance characteristics.
• Prolonged barrel life.

[Yogi 117]

No problemo.
Here's some more numbers for comparison.

9mm/Kahr PM9 124gr Speer Gold Dot HP +P 1075 fps 3.0
9mm/Glock 26 124gr Speer Gold Dot HP +P 1180 fps 3.46
9mm/Glock 19 124gr Speer Gold Dot HP +P 1227 fps 4.02
9mm/Glock 17 124gr Speer Gold Dot HP +P 1252 fps
9mm/CZ75B 6” 124gr Speer Gold Dot HP +P 1327 fps

I like chrono data...

+1, I like the data also. Thx for this comparison on the 124 +P Gold Dot with different weapons. This is one of my favorite G26 SD Carry rounds. Much appreciated.