Polygonal Rifling... benefits and drawbacks.

[Nolo]

I've heard that polygonal rifling increases the velocity of whatever you're shooting relative to normal barrels, but by how much? Magpul said that they were gonna use PR on their PDR concept, but by how much would it increase velocity? Would it make that 12.5" barrel act like a 14.5" barrel? A 16" barrel? How much "longer" does it make your barrel? or, probably a better question, how much barrel does it allow you to save?

 

[Cu-Melter]

The "Benefits" of polygonal rifling are-
Less Bullet Distortion
Less Fouling
Trailing edge disappears as bullet travels down the bore

These are the real-world benefits.

One of the key elements present in Ruger's Target M77......

Drawbacks-
Someone will find fault with it, for sure-
Throats may errode quicker in grossly over-bored chamberings....
I can't think of a drawback w/the experience I have w/them.
But someone could find fault w/it if given enough time.

 

[waterhouse]

http://www.10-8forums.com/ubbthreads/showflat.php?Number=30623&page=

It is not a complete answer to your question, but the above thread shows a comparison between a polygonal Noveske and others. The 12.5 Noveske approaches the velocities in the 14.5" barrel but does not reach them (at least generally . . . I believe it did reach and exceed a LMT 14.5" barrel with MK 262 in one of Wes' charts.)