how much velocity gain from polygonal rifling


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gofastman
September 21, 2010, 12:30 PM
how much velocity do you gain from it?
the reason I ask is I'm curious how much velocity one would actually gain from a conventional rifled 6" barrel in a Glock 20.

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LawofThirds
September 21, 2010, 12:52 PM
Apparently...not much. The lone wolf barrels generally show about a 20 fps spread (either up or down) from the polygonal rifling.

gofastman
September 21, 2010, 04:23 PM
are you talking about the 6" version of the LWD barrels or the stock replacement size?
a 20 fps gain seems almost impossibly low :what:

9mmepiphany
September 21, 2010, 05:10 PM
It does seem low, but remember that polygonal rifling is usually faster than conventional rifling (better seal, I believe), any velocity you'd gain from the longer length would first have to off-set that lost

gofastman
September 21, 2010, 06:17 PM
anybody know the gain a Glock 6" barrel would give over the stock setup?

usp9
September 22, 2010, 06:17 AM
The figure I've seen used is a 3% gain in polygonal barrels, however, not all barrels are equal. The quality and process of the machining varies greatly among both conventional and polygonal barrels. A match grade conventional barrel may be close to or as well sealed as a polygonal tube.

Steven Camp wrote this Sig 225 test, in which he purposely compares it to a Glock of similar ilk. Excellent article. The comparison is near the end. The results seem to indicate that the polygonal does offer higher velocity, if only slightly.
http://actionsbyt.blogspot.com/2008/05/stephen-camp-sig-sauer-p225.html

Ben86
September 22, 2010, 12:32 PM
The main benefit to me with polygonal rifling is easier cleaning. The fouling seems to scrub off noticeably easier with polygonal rifling. There is only a marginal increase in velocity (the manufacturers really exaggerate this too much). Better accuracy? There are so many other more important factors that effect accuracy I have a hard time believing it really makes a difference. It's more of a marketing ploy. I wouldn't feel more compelled to buy a gun just because it had polygonal rifling.

gofastman
September 22, 2010, 01:57 PM
Apparently...not much. The lone wolf barrels generally show about a 20 fps spread (either up or down) from the polygonal rifling.
could you please clarify this a bit, its confusing as hell

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