Which 9mms have polygonal bores?

[Walt Sherrill]

I wasn't being a smart-$$$ when I wrote what I did. Yours is the first 75 (in any form) that I've ever heard of with a polygonal barrel. Period. And I've been moderating on the CZ Forum for years. That's very, very unusual -- and I don't know of another like it anywhere.

Two tones are also rare -- but seen from time to time.

And its really rare to find one that has been used by a police department, anywhere (perhaps only off duty), because unless its a Compact D (also called the PCR), its got a safety, and most police departments like decockers. If its got a decocker, its a model more commonly called a 75 Compact D or PCR (Police of the Czech Republic).

Some factory one-of-a-kind guns get loose from time to time. Maybe you got one of those.

 

[Joe D]

Gosh, does this mean I have to stop shooting lead bullets in my Glocks?

 

[Walt Sherrill]

One acquaintance, a shooting instructor and Master-level IPSC/USPSA shooter, shoots a lot of Glocks, and shoots a lot of lead. He says the secret is properly sizing the bullet to the barrel. He never has problems with leading.

 

[rageofangels]

DISCLAIMER...I'm about to sound like an idiot.

What's the difference between teh polygonal and conventional type?

I didn't know either.

 

[atblis]

I wonder

CZ was selling the 6" machine pistol barrels weren't they? I wouldn't be surprised if those were hammer forged polygonal barrels to help cope with the extra wear. Conceivably, one of those could have ended up in a pistol

 

[candr44]

Walt, I didn't think you were trying to be a smart a$$. Sorry if you took any offense. I really don't know the history of this pistol other than what I know about the person who sold it and that it was obviously carried alot. To tell you the truth I don't care if it is rare, or original, polygonal or conventional rifeling, or it's history. All that matters to me is I like this gun and that it's accurate and reliable. It has made a cz fan out of me along with my cz 83.

 

[hksw]

Quote:
Originally Posted by gudel
my HK USP 9 has polygonal bore.

Pre 93 has conventional hammer forged.

Ed

Hammer forging does not mean polygonal rifling. It is merely one of a number of processes to produce rifling into a bore. Conventional rifling can be produced with hammer forging.

Here are the general configurations of the bore cross section of some types of rifling.

 

[usp9]

HKSW, Great post!

Thanks, that is a great post. May I ask where the diagram came from. If it is a web, what is the web address?

 

[Walt Sherrill]

Walt, I didn't think you were trying to be a smart a$$. Sorry if you took any offense.

Nope, no offense taken -- and given, I hope.

My second message, after having reread my first response, was an attempt to NOT come across as a smart-a$$. It was a serious observation.

CZs with polygonal barrel are about as common as SIGs or S&Ws with polygonal barrels.

 

[hksw]

During my luch hour, upon reading this thread up to my initial post, I drew the diagram using MS Paint. Didn't take long.

 

[wbond]

Why the fascination?

I think Hk's do also. Never gave it much thought. Beretta's don't, at least not the models I'm familar with. Why the fascination?

Polygonal bores allegedly give about 40 fps more velocity from same ammo than land and groove. That's important for my anemic 9x18s. The CZ-83 9x18 has chrome plated polygonal bore. Nice.

As for accuracy, I'm not sure that matters. However, I can say my CZ-83 9x18 is amazingly accurate, even at distances you'd never think of using that small a gun at. My CZ-83 9x18 is my only polygonal and it's also my most accurate gun. Coincidence? Don't know.

Polygonal bores last longer too. That's an accepted fact. The greater velocity is considered accepted fact by some and rumor by others. I don't know for sure about the velocity claims. As for accuracy, I don't know if it's more accurate, but I know mine is very accurate.

My CZ-83 9x18 is both polygonal and chrome plated. I love it. The chrome plating makes it very easy to see if it's dirty and prevents rust (wet climate). Poly + Chrome = Nice

Since my CZ-83 9x18 polygonal is my favorite, I figure I'd like to try a 9mm Para with polygonal.

Anyone know which 9mm Para polygonal bore guns are chrome plated-lined inside? Are there any stainless steel polygonal bore guns?

 

[wbond]

Polygonal bores and lead bullets a NO NO!

I just read a fellow's post about using lead bullets in his Glock.

I'm not a gun expert, but I know that is Verbotin!

I just took an NRA basic handgun and concealed carry class required by State of Oregon to get my concealed carry license. The NRA teaches this course.

Great 4 hour class. 2 hours of book learning and demos. 2 hours of shooting instruction and live fire. Awesome for $35. I wish my home State of Washington offered a similar class. The coverage of laws related to OR state laws about concealed carry and self defense were really helpful.

The two NRA instructors both warned that lead bullets are forbidden in polygonal rifled bores.

They said at a range where these guys are range masters, a local cop was shooting his Glock with lead target rounds. His gun blew up in his hand and he had to go to hospital for serious hand burns. He kept is eyes due to required shooting glasses.

The gun was blown in half with grip being one piece and slide and upper being other piece. We were shown a photo of another Glock that same thing happened to at another shooting range.

The instructors said the moral of the story is DO NOT use lead bullets in a polygonal bore. If you have been doing this, clean your barrel with a good lead removal chemical followed by a good powder removal chemical. Then have your gun inspected closely by a gunsmith or by the company that makes it. Then STOP shooting lead bullets in your polygonal.

Those NRA instructors apparently say all this stuff at every class, but made a big point of it at this class because I have a polygonal CZ-83 9x18 and another two people had Glocks.

Lead Bullets + Polygonal Bore = Potential Big Trouble

However, if you stick to copper jacketed or steel jacketed copper washed bullets, then polygonal bore is superior. If it's cheaper to manufacture polygonal bores, then that's another good point in favor of polygonal.

For 9x18 ammo, polygonal bores are especially helpful because polygonal can stand up to steel jacketed bullets better than land and groove. Since steel jacketed 9x18 is common, polygonal is extra helpful to 9x18 owners.

Polygonal bores are awesome, if you don't shoot lead bullets. I don't want to shoot messy lead bullets anyway. So for me, polygonal is best.

 

[wbond]

Using lead bullets in a polygonal is BAD!!!

Polygonal barrels are superior in many ways, have one weakness. They don't like lead bullets. Using lead bullets in a polygonal is proven dangerous and the manufacturers of polygonal strongly warn against it. Glock specifically warns against it because Glocks have blown up from the practice in the past. Don't use lead bullets in a Polygonal. That's asking to be called lefty.

The NRA, or at least the two NRA instructors who taught my class, strongly warn against lead bullets in a polygonal barrel.

Your friend is playing with fire. Based on what you said, so far he has the expertise to flirt with disaster and get away with it, but the general public should NOT shoot lead bullets in a polygonal barrel. Period.

As I understand it -- but this may be incorrect -- polygonal barrels are very effective for a given diameter, but are less expensive to manufacture. Then too, the vast majority of handgun shooters buying new service pistols probably DON'T shoot lead. So a lower-cost alternative which does not suffer performance degradation, is arguably a good business decision.

One acquaintance, a master level (professional) shooter uses lead in his Glocks -- losts of rounds -- without problems. He says the secret is sizing the bullet to the barrel, as some barrels have overlarge dimensions -- and that extra space allows more hot gases to hit the lead and that causes leading.