[Sierra9]

Has anyone chronographed any given bullet fired from a stock G29 versus a G29 with an extended barrel? I plan to do this when I get my just-ordered KKM 4.75" barrel, but I'm interested in the experience of anyone else.

[AA#5]

You may find that you actually lose some velocity. The Glock's polygon rifling allows a substantial velocity gain over the aftermarket barrel with standard rifling.

[TDC20]

A very rough estimate is 75fps per inch of barrel length. A little bit more for light bullets at higher velocity, maybe a little less for heavy bullets at lower velocity. This is based on my results with a G20 4.6" stock barrel vs. a LWD 6" barrel. It could (and probably does) vary a little bit with the shorter G29 barrel.

That should get you into the ballpark.

[_The_Shadow]

Here is a target load I shot from two different barrels...
10mm June 27, 2009 test
S&W 1006 with factory barrel 5.00”
Temps 99 °<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
<o:p></o:p>
Lyman 156.0 gr Devastator HP 0.401” 1.255”
Power Pistol 7.2 gr CCI 350
Velocity 1115-1138 fps
Primers OK
<o:p></o:p>
Glock 29 with factory barrel 3.78”
Temps 99 °<o:p></o:p>
Lyman 156.0 gr Devastator HP 0.401” 1.255”
Power Pistol 7.2 gr CCI 350
Velocity 1009-1053 fps
Primers OK

[gator378]

Originally Posted by AA#5

You may find that you actually lose some velocity. The Glock's polygon rifling allows a substantial velocity gain over the aftermarket barrel with standard rifling.

My G20 Barsto barrel is always at least 20 fps faster than the Glock barrel. This has been true the last few years consistently. After going through 2 OEM glock barrels that had really bad smileys, The first thing that gets modified on the glock is the barrel is replaced. Not a fan of Glock barrels or the polygon rifling. Otherwise they are very good and reliable and almost indestructable pistols. A few thousand rounds threw mine and no problems yet except for the occasional spring whose lifespan has been exceeded by about 300%