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Discussion Starter · #1 ·
I carry a K9 with 3.5 inch polygonal rifled barrel and was wondering if anyone had done any testing with a chrony to see how the velocity compared to that of a 4 inch barrel with regular rifling? I've heard rumors that the polygonal rifled barrels are supposed to have a better barrel/bullet seal and that they don't lose as much velocity as a regular rifled barrel of the same length. Thanks!
 

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1951 - 2011
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Hello. I will give you what I have, but I've not checked into this closely:

SIG Sauer P225 w/3.86" conventionally rifled bbl:

Federal 115-gr. JHP: 1086 ft/sec
Corbon 115-gr. DPX +P: 1163

Glock 26 w/3.46" polygonal rifled bbl:

Federal 115-gr. JHP: 1111 ft/sec
Corbon 115-gr. DPX +P: 1181

The two loads shown are ten-shot averages fired 10' from the chronograph screens from each pistol. It appears based on this very limited number of loads that the shorter bbl'd Glock is a bit faster than the slightly longer bbl'd P225. I suspect that there might very well be some loads that get higher velocities from the slightly longer bbl, but just don't have loads common to both guns tested.

Best.
 

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Discussion Starter · #3 ·
Thanks Stephen...I'll have to spend a bit more time looking. Someone has done this, I'm sure, I just haven't seen the results yet.
 

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K9 - I would not expect a difference to be that great to be honest tho yes - arguably polygonal may provide better obturation but IMO not enough to really matter.

I forget the figures but it is IIRC reckoned that an inch of barrel length has a 25-50 fps difference factor - tho I doubt it is a linear deal. Rifles show this up most easily.

From say 2" on a snub thru 5" on a full size 1911 I'd expect the gain with length increase to be more exponential or shall we say logarithmic in nature. I am of opinion that 2" is severely under utilizing most rounds and that we need perhaps 3" and up to start getting good figures.

Once 4" is exceeded then the progression tends to become more linear. I am personally happy with 3 1/2" onwards for practical purposes tho my R9 pocket piece is well under that.

I always have way more chrono testing to do than I ever seem to get done :rolleyes: :wink:
 

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I have chrono'ed the Hornady 230gr.,XTP,+P (#9096)out of one of my 5" Colt's and outta my Beretta Storm with it's 16" bbl. The 5 shot average is only 67 fps. difference in vel's.In rifles the most difference per inch of bbl will be in the weapons/ammo with the most velocity. When you get way down to the pistol velocities a inch or two makes hardly any difference. What will make the most difference with the slow pistol calibers is the makeup of the bullet. My CCW and hunting handguns were thoroughly evaluated with bullet makeup the primary consideration. Keeping in mind that a fairly big change in velocity will effect bullet performance. I just, have not found pistol bullets have a big enough change in their velocities to worry about. Especially at the closer CCW ranges that we will be training at or real life shooting at.----------
 
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