Honing chambers for easy extraction

[J-Bar]

I've heard that a side-by-side shotgun's chambers can be polished out with a brake cylinder hone on a hand drill...makes it easier and faster to dump empty hulls during a cowboy action match.

Have any of you done this, any dangers, recommendations? I have an occasional hull hang up and it's frustrating, but don't want to risk ruining a good gun.

Thanks.

 

[bkjeffrey]

Never done any SxS chambers but I have polished quite a few pump gun chambers, but not with a brake hone. Brake hones are pretty aggressive and will leave a swirl criss-cross pattern in your chamber. I use Turtle Wax polishing compound on a 12GA bore mop attached to a cleaning rod in a hand drill. Run a liberally soaked mop through your chamber for 20-30 seconds at a pop until a mirror surface is achieved on your chamber walls. This will make extraction very fast and smooth with no hangups. Remember to clean all the polishing compound off real well and lightly oil. If you get it slick enough your shells will slide out slicker than pig snot....

Hope this helps................

 

[Sam1911]

[Duplicate Threads Merged]

 

[Jim Watson]

The Flex-Hone is made for the purpose. It looks like a brush with balls of abrasive on the ends of the bristles. Rather expensive for one gun, especially since they warn not to use anything but their oil; but anybody working on CAS shotguns would have one.

Brownells has a device like a brake hone but with finer stones so as to not leave a coarse finish in a shotgun barrel.

bkjeffrey's system is mild enough to try at home.

 

[Clark]

I used flex hone on the master brake cylinder in the 60's.

Someone sold me his Taurus stainless 357 magnum revolver. Look how rough the chambers are. I have to shoot wimpy loads to get extraction.

Here is a hole I bored in 2" thick steel late last night. Notice how smooth it is in comparison. This is just a clearance hole, not a chamber.. sheesh.

 

[rcmodel]

You can do a good job on shotgun chambers with nothing more then a slotted dowel rod, a drill, and flaps of 240, 320, 400, and 600 grit black Wet or Dry emery paper & oil.

When you get done with the 600 grit, follow with JB Bore Paste or buffing compound on a mop.

But whatever you use, it is critical to put some sort of depth stop on the rod so you don't go in past the end of the chamber.

rc

 

[J-Bar]

I am not familiar with JB Bore Paste...where can I get it? I have some jeweler's rouge...would JB be better?

I assume one would not want to polish deeper than 2 3/4 inches, or should I also polish the little bit at the end where the crimp would open up?

 

[rcmodel]

Look inside and you can see where the chamber ends and the forcing cone starts.
That is 2 3/4", as chamber length is measured to the open crimp length.

If you have jewelers rouge, that should work fine following the 600 grit paper.

rc

 

[Red Cent]

No matter how you polish keep the instrument moving forward and back. I use the slotted dowel rod and sand paper.

RC, it wouldn't really hurt anything to polish past the chamber and into the forcing cone. If the forcing cone has not been lengthened, you can round off some the angles with no worry.

Don't get too aggressive with the lower grit paper.

If the chambers are spec and you can easily pull them from the chamber, a very good polishing with 800 grit will do.

In my cowboy years, I have encountered a number of double shooters having problems with certain hulls. Your occasional "sticker" doesn't sound like it. Then the next question would be "do you reload".

I know some SxS shooters that will not use the ribbed hulls and swear by the slick green Remington STS. BTW, the STS is a smidgen longer than a AA hull. The other day, a friend and cowboy shooter traded for a 20 gauge double. Could not get them to come out with inertia. He brought it to the house and I lengthened the forcing cones and generously polished with 800 grit paper and finished with the balls on a stick. Still would not come out. He ran out of shells and had a buddy of ours to pick him some up at the local cowboy wholesaler (local wholesaler sells to cowboys= good price). He got him Estates. The ones with ribs. They work wonderfully. Go figure.

 

[rcmodel]

RC, it wouldn't really hurt anything to polish past the chamber and into the forcing cone.

I know, but I figured if I have to tell somehow to do it, I might error on the side of caution about going to far in with the course grit paper.

rc

 

[Red Cent]

roger that.

 

[J-Bar]

Thanks for the info, pards.

To answer some questions, I reload and compete in blackpowder categories in cowboy action shooting. The gun in question is an SKB 100. I polished the chambers a couple of years ago with jeweler's rouge on a mop, and the chambers have a mirror finish.

I have used Winchester AA hulls, old and new, and the black ribbed Remington game loads, low base, both brass and steel. This gun seems to dump the cheapie Remingtons more reliably than the AAs, but one will still hang up occasionally, even though I mop the chambers with Ballistol between stages. I have not tried the STS hulls, but my poor experience with the AAs leads me to think they might be the same.

The extractor pulls the hulls out far enough that the metal base is free of the chamber, so I don't think the base metal is a factor.

I'm thinking that if I could just polish the chambers into kinda a cone, with the breech end a hair bigger in diameter than the muzzle end, then the whole hull surface would break free of the chamber walls when the extractor ends its excursion. Like a tapered brass cartridge.

Is that a foolish thought?

 

[gdcpony]

What about trying this on a rifle or handgun chamber? I have several chambers I thought about mopping with a buffing compound.

I read this (very technical):
http://www.varmintal.com/a243z.htm

CONCLUSION.... A polished or low friction chamber decreases the plastic strain near the case head and reduces the chance of case head separation on subsequent reloads.

And this:
http://www.varmintal.com/afric.htm
More good info.

 

[bigedp51]

I collect milsurps and polish my chambers every time I get a new one to remove the years of garbage that is sticking to the chamber walls. As said above I use J&B bore paste, a shotgun mop, short section of cleaning rod and a cordless drill.

J&B bore paste is softer than steel and bench rest and competitive shooters use it to clean their bores. If your shells chamber and extract in your generous shot gun chamber I see no reason to clean/polish the chamber unless you have plastic residue sticking to the chamber.

This reads as as the shotgun chamber is not a tight fitting custom chamber you find on target rifles and should have room for the shell and the dirt in your duck blind.
(sorry I have never had the need to polished any of my shot gun chambers)

 

[bigedp51]

gdcpony

CONCLUSION.... A polished or low friction chamber decreases the plastic strain near the case head and reduces the chance of case head separation on subsequent reloads.

Chamber friction on a center fire rifle is a bit different than a lower pressure shotgun chamber. The rifle cartridge case was designed to "grip" the chamber walls and deliver less bolt thrust to the bolt face. Proper fire forming and resizing will control head gap clearance and prevent case stretching in the web area.

Below a .303 British chamber with excess headspace and head gap clearance fired at 45,000cup or 49,000 psi.
And why I polish my milsurp chambers with J&B bore paste. Maximum 12 gauge MAP is 14,000 psi.



SAAMI Shotgun Pressure Specifications

Shotshell Maximum Average Pressure (MAP) in PSI

10 gauge 11,000
12 gauge 11,500 (except 3-1/2 in.)
12 gauge 3 1/2 in.14,000
16 gauge 11,500
20 Gauge 12,000
28 gauge 12,500
.410 Bore 2 1/2 in. 12,500
.410 Bore 3 in. 13,500

 

[Clark]

gdcpony
Member


Join Date: August 27, 2008
Location: Sherrodsville, OH
Posts: 380
What about trying this on a rifle or handgun chamber? I have several chambers I thought about mopping with a buffing compound.

I read this (very technical):
http://www.varmintal.com/a243z.htm
Quote:
CONCLUSION.... A polished or low friction chamber decreases the plastic strain near the case head and reduces the chance of case head separation on subsequent reloads.
And this:
http://www.varmintal.com/afric.htm
More good info.
______________

And we should put our radiators out front, to protect our bumpers.

 

[gdcpony]

I think those pages were basically saying that with the items we have commonly available a polishing job would be beneficial. It would allow the case to slip some rather than catch in the chamber and only the unsupported head would stretch back to meet the bolt face. at the same time he pointed out that to little friction and you put too much load on the bolt face risking damage. He gave some good examples, and I have thought over and over again about trying them out.

 

[bigedp51]

Excess bolt thrust adds up!



Did you notice Varmint Als little *NOTE about oil in the chamber............. and over twice the bolt thrust.

 

[gdcpony]

Excess bolt thrust adds up!



Did you notice Varmint Als little *NOTE about oil in the chamber............. and over twice the bolt thrust.

Yep I did. I also have found that not cleaning the lube off your finished cases can do the same thing. I was chasing a pressure problem with minimum loads! Then I realized the real issue.

I am not referring to lubing my chamber, just a more polished finish. While modern rifles are great from the factory, I wonder at some of the finishes and if they can be improved.

 

[Clark]

I put molybdenum disulfide lubricant [bore cream or grease] in the chamber. I hear it has a breakdown at > 50kpsi.

 

[Red Cent]

Holy rocket science!!!!



JBar, cohesion may be the problem. 'Course that stuff you're usin' would gag a maggot.

I would wipe the chamber dry as in bone. That Ballistol, while biodegradable, is a very good lubricant. And that could cause some stickin'. And you ain't never goin' to have a 10-12 stage match shootin' black powder without somethin' stickin'.

Now if you would give this new fad a try you may not have the problem. They say the new smokeless burns pretty decent.

 

[bigedp51]

On a military Enfield rifle with a cartridge with .058 rim thickness and the headspace at .074 maximum you have .016 head gap clearance.

On my Stevens 200 I have .001 or less head gap clearance.

I have NOT polished the chamber on my .243 because the case can only move .001 at most and the brass is more than capable of stretching and springing back that much without any strain.

On the Enfield I HAVE polished the chamber because the case can stretch .016 and have case head separations.

As far as I'm concerned Varmint Als theoretical computer generated software information might be interesting in theory in a rife with long headspace, it doesn't apply to my .243 with .001 head gap clearance.

Bottom line, your cases can't stretch if you don't let them.

 

[Slamfire]

What about trying this on a rifle or handgun chamber? I have several chambers I thought about mopping with a buffing compound.

I read this (very technical):
http://www.varmintal.com/a243z.htm

Quote:
CONCLUSION.... A polished or low friction chamber decreases the plastic strain near the case head and reduces the chance of case head separation on subsequent reloads.

And this:
http://www.varmintal.com/afric.htm
More good info.

Varmint Al is 100% correct and his finite element modeling does prove the obvious point that cases are the weakest link in a centerfire rifle. The same is true for all mechanism that use cartridges, shotguns included, that the case is the weakest link in the system. For cartridge guns a case is a gas seal not a structural element. The thin sections of a typical rifle case will rupture with 650-700 psi and therefore the action must support the case.

But I would be cautious about using any aggressive measures in polishing rifle chambers. I would be worried about throat damage, making an oval chamber, or removing material.