I've got a 300 RUM that I just got done building. It's set up with .003" headspace. After shooting a few rounds through it I've noticed the brass is sticking in the chamber. This is with 2 different factory loads, primers are still round, no signs of high preasure except the sticking. I've got another 300Rum that I used the same reamer on and it handles the factory ammo fine. I used a standard reamer, nothing fancy. I did noticed some tooling marks on the spent brass. Could this be causing it to stick? I'm not a pro, just like to work on my own stuff. Whats the best way to polish a chamber once the gun is assembled. What else could be causing the cases to stick?

I have a M70 6.5x55 about 1999 vintage that has a real rough chamber shoulder. Fired Brass shoulder is real rough with tool marks. Pisses me off. I get hard bolt lift/extraction also. Brass shoulder looks like shit with groves like a old record album or worst.

Im going to polish the dam thing. Maybe some dab of 400 grit on a fire formed case shoulder .

Ringing in the chamber certainly can cause extraction problems. Also if the barrel is blued it increases friction too. Try polishing the chamber with 400 paper wet with WD40 or Rem oil spray then 600 paper also wet, after that take a piece of emery cloth and and wrap it around your mandrel cloth side out and burnish the chamber with it.

You can also take a large bore brush and wrap some 4/0 steel wool around it and saturate it with wd or etc and turn it in the drill. Make it a fairly snug fit in the area of the tooling marks on the brass. You can also slather a little fine silicon carbide powder (600 grit) on it as a final polish. You'd be surprised how little smoothing is required to greatly improve extraction, depending on how bad the chamber is..

If you have rings in the body of the brass, you may have trapped a chip between the reamer and the chamber and cut a groove. The only way to repair is to cut part of the tenon off and rechamber. I wouldn't use anything finer than 320 grit to polish as a finer grit may make the rounds stick to the chamber.
Butch

I wouldn't use anything finer than 320 grit to polish as a finer grit may make the rounds stick to the chamber.
Butch[/QUOTE]

Are you sure you ment what you typed?

I meant what I typed. It is the same reason barrel makers don't use fine grit to lap barrels. Copper will stick to a slick barrel. Don't believe me? Call your barrel maker.
Butch

Butch, most lapped barrels are done with 800 grit, some makers go finer than that. There is a point where a finer finish can cause fouling but it's a whole lot finer than that. Extraction is always better with a finer finish. Give the cases a coarse finished chamber to grab and they will, give them a slick finish and they slide out.

SWD, where did you get your info?
Butch

Butch, I'm a gunsmith by trade. We have a Pratt & Whitney sine bar rifling machine in our shop. Also some of the barrel makers websites have info on their lapping process. Lilja had alot info at one time but it's been a few years since I checked his site.

I have been in Dan's shop and have talked directly to the guy doing the lapping. "...one-eighty grit is as fine as we go. Any finer and accuracy suffers." Quote!

I use 180 grit emory cloth with WD40 and with the barrel spinning at 1200 RPM, followed by a series of rapid in and out strokes with a fresh piece of "Green" Scotch Brite pad to give the chamber that fresh "honed" cylinder appearance. The fine cross hatch finish looks great and the brass comes out perfect. Years and years ago I use to think chambers needed a good high polish finish, but have since changed my mind...

Polish your chambers with 320 to 400 grit silicon carbide paper wet or dry paper. Use it wet with to remove the tool marks. Don't polish so much you jug the front of the chamber.
Remember reloading dies are polished and they see far more drag than any chamber produces on extraction.

Ireload2,
My press has a handle a little longer than my bolt. What would happen if you had a press with a rifle bolt handle?
Butch

quote:

Originally posted by ireload2:
Remember reloading dies are polished and they see far more drag than any chamber produces on extraction.

Just think of what would happen if you didn't lube your brass...

Butch and Wespac...
Think about what I said.

1. All sizer dies are polished.
2. No chamber is used for resizing.
3. No bolt ever pulls on a case a tight as those in a sizing die.
4. Everyone knows that a smooth polished loading die works better than a rough die. Compare any Herter's sizer (rough) with almost any other brand and you will find the other brand requires much less sizing force.
Then polish the Herter's die and it too will require less force to resize a case. A rifle chamber requires far less extraction force because the brass contracts after firing. The smaller the ridges in the finish the easier the extraction is.

If you guys have a secret what is the optimum surface texture? In Ra? Trouble is you don't know because you don't have a profilometer.

I'll make one comment and let it go. A high polished chamber can cause extraction problems.
Butch

quote:

Originally posted by butchlambert:
I'll make one comment and let it go. A high polished chamber can cause extraction problems.
Butch

Sure if you polish the taper out of the chamber in the process. But you will never be able to provide the theoretical basis for your claim.

Take the gun to a gunsmith and let him do it for you or send it back to the factory.

A very highly polished chamber will not let the brass grip it and head pressure goes way up as does brass stretching. The effect can indicate high pressures and hard extraction when there isn't any over pressure. There must be some friction in the chamber.
Lapping a bore is different and even if marks are left, they run the same direction as the bullet. Crosswise tool marks cause fouling.
My .44 SBH has just passed 57,650 rounds, is as smooth as glass and doesn't lead or copper foul so I don't believe a barrel can be made too smooth. (The gun just shot a 5 shot 1" group at 100 yd's.)
Look at the hundreds of jars of JB Bore paste used by BR shooters.
A round ball muzzle loader must NOT have a highly polished bore or accuracy will go away. But we are talking modern stuff here.

quote:

Originally posted by bfrshooter:
A very highly polished chamber will not let the brass grip it and head pressure goes way up as does brass stretching. The effect can indicate high pressures and hard extraction when there isn't any over pressure. There must be some friction in the chamber.

Well said! I have polished several chambers with a bore mop and Flitz, which I feared would produce to highly polished of a finish, but (I suppose due to the original finish in the chamber) several minutes of polishing with the Flitz/Bore mop combo, left the nice 'honed cylinder' finish Westpac mentioned, and extraction etc. was just perfect.

quote:

A very highly polished chamber will not let the brass grip it and head pressure goes way up as does brass stretching. The effect can indicate high pressures and hard extraction when there isn't any over pressure. There must be some friction in the chamber.

No, not true.
It is common knowledge that some machine guns have case oilers to prevent friction between chamber and the cartridge case.
When a chamber is plated such as is done with many military barrels the plating improves the smoothness of the surface finish. The plating improves the surface by cutting the RA value in half. Thus a 32 RA will go to about a 16 RA.

If you are having extraction problems etc your loads are too hot , there is nothing wrong with the chamber being highly polished.

Here is an analysis of chamber finish and pressure

Gotta go with Butch.

Also, barrels intended for lead bullets are lapped much finer than those intended for jacketed bullets....just ask Lilja or Shilen.

Comparing a polished sizing die to a bolt action chamber, I would think would be unfair, since one uses a sizing lube and the other does not. RCBS, and others, make stuck case removers for a reason.

And, IMHO, Al's computer analysises of polished chambers have no basis in impirical fact......pretty pictures though.

Hope this helps....

Kevin

I have years of experience with muzzle loaders and a super polished or chrome plated bore will not shoot good.
I did more research and found it is also true with modern rifles. My bores might not be as polished as I think because I shoot high antimony boolits which is abrasive. There ARE marks in the bore!
I might have to recant a bit on what I said.
I gave it some thought and if the bore is super polished, the bullet will tend to skid a little before taking the rifling. Can that be the reason for more fouling? Lapping with the proper grit will leave longitudinal marks in the bore that can aid a bullet's grip.
As far as a polished chamber, go ahead and do it! Then oil the cases and report back to tell us how long your locking lugs last and how long the cases last. How can you compare a blazing hot machine gun to a bolt gun? Seems to me some autos have grooves in the chambers to retard the bolt opening too fast before pressure subsides. None of those cases are reloaded either.
How many gun makers will tell you to grease the brass? Call any rifle maker and ask if it is OK to dip your loads in oil before chambering. How many of you leave sizing lube on your loads? How many of you oil the chambers before shooting? Have any of you seen the pictures of cracked locking lugs?
I remember the S&W revolver chambered for a bottle neck case that would bind the cylinder if the chambers were not cleaned of all lube. They quit making them because of brass set back problems. Rougher chambers would solve that but then cases sticking in the chambers made it hard to get them out without the camming power of a bolt gun. You just can't push out 6 stuck empties with a little rod.
Be my guest and polish those chambers until they are like glass, never catch me doing that!

How can anyone relate case sizing to case shooting? Cases are smaller then a chamber and expand to the chamber walls, then rebound to a smaller size again.
Running an expanded case into a size die forces the brass to a smaller size and there is only rebound to the larger size. Since it can't, lube is needed and the die must have a high polish so the brass can be removed. Two completely separate operations.