AR15.Com Archives
 DIY polishing a chamber?
Firebird69  [Team Member]
2/18/2011 9:08:19 PM
title says it. necessary? can it be done DIY?
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CAC01  [Team Member]
2/18/2011 9:28:34 PM
Can't polish a chromed chamber, period. Polishing a stainless chamber is a bad idea. Makes it very difficult on extraction.
458winmag  [Team Member]
2/18/2011 9:46:39 PM
Nope.
Yes, for DIY but why?
shadowcop  [Team Member]
2/18/2011 9:49:55 PM
Never mind
JBnTX  [Member]
2/18/2011 10:30:43 PM
Why do you need to polish a chamber?
Are cases sticking?
Firebird69  [Team Member]
2/18/2011 10:43:07 PM
just curious. thanks
PR361  [Member]
2/18/2011 11:18:11 PM
Originally Posted By CAC01:
Can't polish a chromed chamber, period. Polishing a stainless chamber is a bad idea. Makes it very difficult on extraction.


Please elaborate. I am very interested in this information.
CAC01  [Team Member]
2/18/2011 11:49:00 PM
Originally Posted By PR361:
Originally Posted By CAC01:
Can't polish a chromed chamber, period. Polishing a stainless chamber is a bad idea. Makes it very difficult on extraction.


Please elaborate. I am very interested in this information.


Considering that hard chrome is in the neighborhood of 70 on the Rockwell C Scale, what are you going to polish it with, diamonds?

A polished chamber will not release a spent case and therefor it can not be extracted.
mmf  [Team Member]
2/19/2011 7:01:11 AM
Originally Posted By CAC01:
Originally Posted By PR361:
Originally Posted By CAC01:
Can't polish a chromed chamber, period. Polishing a stainless chamber is a bad idea. Makes it very difficult on extraction.


Please elaborate. I am very interested in this information.


Considering that hard chrome is in the neighborhood of 70 on the Rockwell C Scale, what are you going to polish it with, diamonds?

A polished chamber will not release a spent case and therefor it can not be extracted.


How is it that a polished metal surface will not "release" a spent case?

If I understand what you posted, a smooth metal surface increases frictional drag?

And that would mean a rough metal surface decreases frictional drag.

Where do you get this information from especially as it applies to barrel chambers?
EWP  [Member]
2/19/2011 7:10:06 AM
It's not that smoother increases frictional drag but increases surface contact and therefor the case sticks to the chamber wall better, I think.

Same reason you don't want to polish a sizing die to a mirror finish, the brass your sizing will stick in a smoother polished die much easier than one not so smooth.
j3_  [Team Member]
2/19/2011 7:53:17 AM
You can polish a chamber. It will help if done correctly on a rough chamber to improve extraction.
One of the major manufacturers had a piece done on one of the TV gun shows and they showed a machine polishing the chamber of the barrel. i believe they said it was after chroming.
Flex Hone sells gun chamber hones. I have used them on a couple of my barrels that had junk chambers and it helped. I did cut a portion off the front of them because I did not like the design for my intended use.
Garandboy  [Team Member]
2/19/2011 9:37:25 AM
Watching Sons of Guns I see. No need for it and isn't a great idea anyway.
helotaxi  [Member]
2/19/2011 9:38:12 AM
Varmint Al would argue to polish the chamber and backs that assertion with rather extensive analysis.

My much less scientific approach showed improved extraction with the polishing of a fairly tight .223 AR chamber and much easier sizing with a polished die. A smoother surface does increase contact during the pressure period where the case has swelled to fill the chamber but even then the brass will actually slide in the chamber because of case taper. If the chamber is rough, it will stretch instead of slide.
gee223  [Member]
2/19/2011 9:55:21 AM
I polished mine when I had a feeding issue. It made no difference, but adding the M4 cuts to the upper fixed it. I also polished the chamber on my M&P 9c to fix a feeding issue. That worked perfectly an has been 100% since. It had a nasty grove a third of the way in that needed flattened because it was catching the rim.

Unless you have a notable defect in the chamber or a tight chamber that affects reliability, it wouldn't do any good. Though a bullet shaped dremel polishing tip and some compound works very well.
GunnyApproved  [Member]
2/19/2011 10:53:01 AM
Originally Posted By Garandboy:
Watching Sons of Guns I see.


Holy Mother, That is the dumbest show on the face of the earth! I wouldn't let those jack-wads touch my guns if they payed ME
All they do on that show is take things others have already done, re-do them rather poorly and then say they invented it. And have you seen their prices!!

OP, unless you having a problem with feeding/extraction, the old saying "if it ain't broke" comes to mind. Unless your asking purely for hypothetical reasons.
madcratebuilder  [Member]
2/19/2011 10:59:35 AM
Originally Posted By GunnyApproved:
Originally Posted By Garandboy:
Watching Sons of Guns I see.


Holy Mother, That is the dumbest show on the face of the earth! I wouldn't let those jack-wads touch my guns if they payed ME
All they do on that show is take things others have already done, re-do them rather poorly and then say they invented it. And have you seen their prices!!


+1000
I reached that conclusion about 10 minutes into the first show. I wasn't sure if it was just me or what. What a bunch of clowns.

PR361  [Member]
2/19/2011 3:44:03 PM
Originally Posted By helotaxi:
Varmint Al would argue to polish the chamber and backs that assertion with rather extensive analysis.

My much less scientific approach showed improved extraction with the polishing of a fairly tight .223 AR chamber and much easier sizing with a polished die. A smoother surface does increase contact during the pressure period where the case has swelled to fill the chamber but even then the brass will actually slide in the chamber because of case taper. If the chamber is rough, it will stretch instead of slide.


OOOOH! Blinded by science!

Nice post, with some good technical info to back it up. As stated, no need to fix what ain't broke, but I have polished a chamber or two that had issues. I use a fired case, from the rifle to be polished, as a polishing mandrel. The brass is softer than the steel chamber and won't damage it, and the fired case is perfectly formed to the chamber to be polished. I run a screw into the primer hole, clip off the head, and use a piece of heavy braided wire and automotive electrical crimps to make an extension long enough to clear the back of the rifle. chuck it in the drill( or by hand if you're the nervous type) slather on some flitz or polishing compound and go. It's a good idea to put some tubing in the reciever to protect it if your wire breaks. This is a situation where LEss is More....don't get carried away, usually doesnt take much to get a mirror shine. make sure to plug the barrel ahead of the chamber with some patches to make it easier to clean when you're done.

Just my opinion, I could be wrong.......

jasonprox700  [Member]
2/19/2011 5:07:48 PM
I had a DPMS (.308) that had extractions problems and chamber scratches on the brass. I went ahead and polished it and it is night and day difference. I would recommend it if you have signs of a rough chamber. If not, I'd leave it alone.
M4quadrail  [Member]
2/20/2011 6:57:37 AM
If the chambe is Chrome lined leave it alone or send it back to the manufacturer! After 20 years of Gunsmithing/Manufacturing I would say have someone with experience Polish the Chamber. I can not figure out where the above information comes from! All chambers that are not CL are polished after the chamber is reamed! Imperfections in an unpolished chamber will cause the cases to stick inside on expansion! WOW some real incredible advice giving is going on here. The first GI kits I built in the early 90s all needed polishing. M4QUADRAIL
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