View Full Version : Dumb Question-Where exactly is the chamber on a Shotgun?

December 26, 2010, 08:02 AM
I want to polish the chamber on my 870. Would the chamber be considered to be the very base of the barrel, or is it the area inside the receiver where the barrel mates with the receiver? Also, just use dry 0000 wool, or should I add some solvent to it?

December 26, 2010, 08:54 AM
The "chamber" is the area inside the barrel occupied by the shell when the gun is loaded.

Pull the barrel and drop a shell into it. ("kerplunk") That whole shell now occupies the chamber which extends inside the barrel up to the end of said shell. ( 2-3/4 to 3-1/2 inches for a 12 gauge depending upon chambering.)

December 26, 2010, 08:55 AM
Right you are:cool:

December 26, 2010, 08:56 AM

December 26, 2010, 09:02 AM
When using wet/dry sandpaper (the dark gray sheets) or steel wool (00-0000), always use a lubricating fluid. 3-in-1 oil will do. So will Break Free, etc. Most any light oil. (Think knife sharpening with a stone.)

I also discovered (with motorcycles) that for the final finish, a last session with the super-dooper-fine-grade steel wool soaked in silver/aluminum polish turns things into mirrors.

December 26, 2010, 09:31 AM
Great! What did people do before forums were invented?

December 26, 2010, 09:33 AM
Hmmm.... good ???

I guess there were many many unaswered questions floating around everywhere.:confused:

December 26, 2010, 09:34 AM
Great! What did people do before forums were invented?

An awful lot of trial and error...

December 26, 2010, 11:31 AM
Let's not forget the forcing cone, the transitional area of the barrel between the cartridge area and the actual bore. Should the forcing cone be included in the definition of the shotgun's chamber? While polishing a rusty chamber may alleviate extraction problems, polishing the forcing cone might actually improve your guns performance.

Depending on its angle, a forcing cone can be from under 1/2 to over 3" long. Some claim a longer (more gradual) forcing cone can improve patterns and reduce recoil (my Remington barrels have had their forcing cones lengthened and polished). You'll see long forcing cones on higher end guns. So, why don't all guns have long forcing cones? For a longer forcing cone, you need a longer chamber reamer, and cutting time is increased. My guess is it comes down to production costs. There is enough interest in lengthening factory forcing cones to support the on-line (http://www.4-dproducts.com/index.php) rental of the tools required.

Back to my question, since the forcing cone is cut with the same tool as the chamber, I'm going to consider it part of the chamber. YMMV.
Great! What did people do before forums were invented?They read books and magazines and hung out at their local club, or gun shop, where they picked the old timers' brains.

December 26, 2010, 06:41 PM
If you don't know what the chamber is, I'd very strongly suggest you do not monkey with trying to polish it yourself.
If you don't know what you're doing, you risk enlarging its internal dimensions beyond safe tolerances by getting carried away, taking it out of round, and screwing up the forcing cone.

I know people do it successfully, but I also know they don't.
A new barrel is not a cheap part.


44 AMP
December 27, 2010, 01:47 AM
If you don't know where the chamber is, how do you know it needs polishing?

December 27, 2010, 07:18 AM
I just wanted to make sure of the exact area. And I don't know if it needs polishing, I just figured it couldn't hurt. I polish all my stainless guns. I probably only have 200 rounds through my 870 Express. Mix of Remington slugs, birdshot, and buck. All whatever was cheapest at Walmart. No problems yet.

44 AMP
December 28, 2010, 02:09 AM
If you start having problems chambering or extracting fired cases, it will likely be due to a build up of powder residue, and perhaps plastic from the cases. A good cleaning is the answer to that. And since you are having no problems, cleaning is all that is needed.

Polishing a chamber is something you do when there is a problem, and one that cleaning won't solve.

Polish the wrong way (or with the wrong materials) and you can change the chamber dimensions, possibly enough to ruin the barrel. It's tough to do it polishing by hand (but you can do it) and incredibly easy to go too far with a Dremel or other power tool. Unless you know what you are doing (and have had practice) and have a need to polish the chamber, I would recommend against it.

December 28, 2010, 08:07 AM
You might find this interesting: http://thefiringline.com/forums/showthread.php?t=406111

For my 12ga 870s, I wrapped a ScotchBrite pad around a 410ga bore brush and chucked it up in a cordless drill. Another method is to wrap a few stands of 0000 steel wool around a 12 gauge brush and chuck the rod in a drill. Make sure to keep the brush constantly moving while running the drill at medium speeds.

December 28, 2010, 11:32 AM
FWIW re EXPRESS problems : I did polish the chamber (especially the shell base area) with electric drill-powered/oiled 00, then 0000, then Silver polish. That gave the gun a fighting chance to extract those cheap/garbagy steel-based cases that are "Winchester SuperTarget" (They're really Steel/strongly attract a magnet and not aluminum)


No apparent problems from that point.
AA's functioned flawlessly (of course)

I'll try the W-ST's in my Grand Dad's 1927 Model-12 tomorrow. If THAT gun won't extract them....