Velocity Loss

[rodwha]

Does anyone have any real world velocity comparison's between the standard vs polygonal rifled barrels? I'm curious just what kind of difference it really makes, especially with the M models. It could possibly make the difference between an optimally performing bullet and a, well, not so well.

[TucsonMTB]

I believe the difference is too small to be significant. In fact, when GunBlast's Jeff Quinn tested the CW45 (http://www.gunblast.com/Kahr-45s.htm) against the P45, the conventional barrel achieved greater velocities than the polygonal barrel of the same length. It's a fun read. You will find the velocities in a nicely organized table and the differences, while small, definitely favor the conventional barrel.

Of course, YMMV ;)

[jocko]

would make no difference to me one way or the other what barrel wasin my gun. It would not proh8bit me from buying a gun without polygonal rifled barrerl. In a defense gun really makes nadda difference. veocities are pro and con of whcih is which. supposable polygonal barrel show a slight increasein velocity but some have done some chron testing which shows standard rifled barresl better, so again it is all in the eyes of the beholder. 5 PM9 will chrono differently with the same ammo, so one has to take chrono results with a grain of salt IMO. To much time being spent on this velocity stuff IMO butr for someit is a fun thing to do and for some a fun to read.

[rodwha]

Had seen somewhere on the net where a Kahr had higher velocities against another pistol with a little longer barrel (unknown make) and assumed it must have been a polygonal rifled barrel. Later I looked up polygonal rifling, and it stated that there was usually an increase. The reasons why seemed fairly logical.
If velocities are more typical to other short barreled pistols I'd have to question the ammo I relied on.
For instance, I understand that XTP's generally require very high velocities to open properly. In a short barrel I doubt the heavy XTP's would expand much at all.
I tend to like the heavy spectrum of bullets for a given caliber, but fear they may not generate enough velocity to expand.
I'm more concerned with 9mm ammo not functioning well.


Anyone check for expansion and found any that didn't work?

[rodwha]

I had been seriously looking at a CW Covert, but my GF likes the M models as she's all about least weight and size. If it's uncomfortable or too bulky she won't carry it. Going to a 3" barrel makes me nervous as to what will work well, and what won't.

[mr surveyor]

what do you mean by "M models"?

There's PM's, CM's, MK's....M&M's...... all with a different weight to consider.

[rodwha]

By M I meant any of the 3" barreled super subcompacts. The weight won't effect the velocity. I just wanted an idea. I read someone's comparison of a 9mm P model (IIRC) besting the velocities of a more duty sized (4" or so) pistol.

[rodwha]

Wasn't certain as to rifling type, but assumed it must have been the polygonal type after reading what I did. Now it seems it may not matter, that Kahr's tend to give higher velocities period according to another guy's findings. Lookin for more info.

[deadhead1971]

Jocko- I know you are up in the 30K round count on your PM9 barrel. At what point does a stainless steel barrel wear out--where accuracy drops off due to the rifling wearing?