P7 Chamber Fluting

jaughtman · November 15, 2021, 06:17 PM

Hey! Been a while since I posted, but I am back! LOL. Recently acquired another HK P7 and in looking it over, the flutes in the chamber of this one appear to be deeper and sharper-cut than the flutes in the chamber of the one that I shoot/carry regularly. Do the flutes "wear down" over time much like barrel rifling? Had never noticed it until holding two up against each other to compare. The new one has been shot/used far less than the one that appears to have the worn flutes. Thanks!

Jaughtman

wild cat mccane · November 15, 2021, 09:12 PM

Flutes on a barrel are usually the term for the outside of the barrel.

Lands and grooves are the transitional rifle barrel twisty you see.

Valleys and hills for the P7 cold hammer forged polygon bore barrel which are claimed to be tighter seal for better pressure while less build up, tearing of the copper jacket, dirtiness, and wear. Blah blah blah on if any of that is true.

Now you are saying the valleys and hills are reduced one to the other? One thing to consider, the age difference might be a manufacturing difference or even variation between barrel make?

A cold hammer forged polygon bore barrel probably isn't seeing a decrease from use for a long while, nor a conventional barrel. Unless you are saying you've shot the living crap out of the gun with 10xs of thousands of rounds?

Informative sight on barrel types. And you can see how "ballistics" can pull barrel patterns from a bullet: https://www.firearmsid.com/A_bulletIDrifling.htm

The most accurate duty gun I've owned is multi PPQs which had traditional and then changed to poly rifling. No change what so ever in my hands.

P7s are a religion. I look forward to people giving you better information.

Jim Watson · November 15, 2021, 10:01 PM

Sorry wildcat the P7 CHAMBER is fluted to ease extraction with its odd gas retarded blowback action.

J., I never heard of the flutes wearing. Does the older gun still function reliably?
As I recall, the original Graygun had an unfluted chamber.

Shadow9mm · November 15, 2021, 10:04 PM

the tools that make the barrels wear out with time. I suspect the flutes in one may have been cut with more worn tooling than the other, while still being within specs.

jaughtman · November 16, 2021, 09:27 AM

Quote:

Flutes on a barrel are usually the term for the outside of the barrel.

*Yes, unless you are dealing with a P7. LOL. Fluted chamber is just one of the many innovations that make these things dear to my heart. I am going to assume just since this one is older it was due to the machining. Still functions just fine - is my faithful bedside-gun.

Jim Watson · November 16, 2021, 09:29 AM

Good point, shadow.
I recall that the chamber flutes are cut even though the rifling is right off the hammer forge.

wild cat mccane · November 16, 2021, 03:08 PM

Well post up some pics! I've never heard anyone complain about seeing a P7 a zillion times

PSP · November 17, 2021, 07:29 AM

I suspect any difference is in tooling adjustments made over time rather than wear. HK steel in very hard and durable.

Here's a photo...

FITASC · November 17, 2021, 10:36 AM

Those flutes also allow the gun to function if the extractor breaks or goes missing.
Love both of mine; but they are getting PRICEY!

Jim Watson · November 17, 2021, 04:45 PM

That is a great picture showing how the flutes extend ahead of the case mouth to admit gas to "float" the empty out of the chamber. It also shows the location of the port to the retardation cylinder, getting high pressure.

I still pick up the occasional striped case on the range, not just P7 but there are a couple of live legal MP5s in town.

Rob228 · November 17, 2021, 04:51 PM

Sheer curiosity...

Can you reload the brass that comes out of a fluted chamber or is it too deformed?

PSP · November 17, 2021, 05:23 PM

Brass is not deformed and is reloadable. The brass has carbon marks where the brass is "floating" in the chamber but no other difference than any other regular smooth chamber.

November 15, 2021, 06:17 PM	#1
jaughtman Senior Member Join Date: March 2, 2010 Location: Alabama Posts: 868	P7 Chamber Fluting Hey! Been a while since I posted, but I am back! LOL. Recently acquired another HK P7 and in looking it over, the flutes in the chamber of this one appear to be deeper and sharper-cut than the flutes in the chamber of the one that I shoot/carry regularly. Do the flutes "wear down" over time much like barrel rifling? Had never noticed it until holding two up against each other to compare. The new one has been shot/used far less than the one that appears to have the worn flutes. Thanks! Jaughtman

November 15, 2021, 09:12 PM	#2
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,625	Flutes on a barrel are usually the term for the outside of the barrel. Lands and grooves are the transitional rifle barrel twisty you see. Valleys and hills for the P7 cold hammer forged polygon bore barrel which are claimed to be tighter seal for better pressure while less build up, tearing of the copper jacket, dirtiness, and wear. Blah blah blah on if any of that is true. Now you are saying the valleys and hills are reduced one to the other? One thing to consider, the age difference might be a manufacturing difference or even variation between barrel make? A cold hammer forged polygon bore barrel probably isn't seeing a decrease from use for a long while, nor a conventional barrel. Unless you are saying you've shot the living crap out of the gun with 10xs of thousands of rounds? Informative sight on barrel types. And you can see how "ballistics" can pull barrel patterns from a bullet: https://www.firearmsid.com/A_bulletIDrifling.htm The most accurate duty gun I've owned is multi PPQs which had traditional and then changed to poly rifling. No change what so ever in my hands. P7s are a religion. I look forward to people giving you better information. __________________ My wife is a pulmonologist (respiratory Dr) and epidemiologist. If you have any questions on COVID, please reach out to me in PM. Last edited by wild cat mccane; November 15, 2021 at 09:30 PM.

November 15, 2021, 10:04 PM	#4
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,969	the tools that make the barrels wear out with time. I suspect the flutes in one may have been cut with more worn tooling than the other, while still being within specs. __________________ I don't believe in "range fodder" that is why I reload.

November 16, 2021, 03:08 PM	#7
wild cat mccane Senior Member Join Date: May 22, 2011 Posts: 3,625	Well post up some pics! I've never heard anyone complain about seeing a P7 a zillion times __________________ My wife is a pulmonologist (respiratory Dr) and epidemiologist. If you have any questions on COVID, please reach out to me in PM.

November 17, 2021, 10:36 AM	#9
FITASC Senior Member Join Date: December 6, 2014 Posts: 6,441	Those flutes also allow the gun to function if the extractor breaks or goes missing. Love both of mine; but they are getting PRICEY! __________________ "I believe that people have a right to decide their own destinies; people own themselves. I also believe that, in a democracy, government exists because (and only so long as) individual citizens give it a 'temporary license to exist'—in exchange for a promise that it will behave itself. In a democracy, you own the government—it doesn't own you."- Frank Zappa

November 15, 2021, 10:01 PM	#3
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,539	Sorry wildcat the P7 CHAMBER is fluted to ease extraction with its odd gas retarded blowback action. J., I never heard of the flutes wearing. Does the older gun still function reliably? As I recall, the original Graygun had an unfluted chamber.

November 16, 2021, 09:29 AM	#6
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,539	Good point, shadow. I recall that the chamber flutes are cut even though the rifling is right off the hammer forge.

November 17, 2021, 07:29 AM	#8
PSP Senior Member Join Date: June 2, 2006 Location: Bowling Green Virginia Posts: 4,487	I suspect any difference is in tooling adjustments made over time rather than wear. HK steel in very hard and durable. Here's a photo...

November 17, 2021, 04:45 PM	#10
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,539	That is a great picture showing how the flutes extend ahead of the case mouth to admit gas to "float" the empty out of the chamber. It also shows the location of the port to the retardation cylinder, getting high pressure. I still pick up the occasional striped case on the range, not just P7 but there are a couple of live legal MP5s in town.

November 17, 2021, 04:51 PM	#11
Rob228 Senior Member Join Date: May 29, 2010 Location: Hampstead NC Posts: 1,450	Sheer curiosity... Can you reload the brass that comes out of a fluted chamber or is it too deformed?

November 17, 2021, 05:23 PM	#12
PSP Senior Member Join Date: June 2, 2006 Location: Bowling Green Virginia Posts: 4,487	Brass is not deformed and is reloadable. The brass has carbon marks where the brass is "floating" in the chamber but no other difference than any other regular smooth chamber.