Polished Brass

[Salvo]

Recently I read about some shooters who use emery paper on a stick to lightly cross-hatch the rifle chamber so that it gets a better grip on the brass.

This makes me wonder why we are polishing our brass... Maybe we should be lightly etching it instead?

[LHitchcox]

Why would you want to invite stuck cases? A rough chamber is not something to be desired.

[hotbrass]

I dont understand it either. With proper headspace there is nowhere for the case to go.

And a rough chamber attracts and holds carbon and brass and all kinds of crap.

[Tightgroups]

I'm not deliberately scratching my rifles chambers. Having clean brass is important, but I dont believe it needs to be polished every time its reloaded, unless you just wont to impress the guy shooting next to you.
I have a tumbler, but seldom use it, most of my cases just get a good wipe down with a clean rag, if there's a vary slight film of lube still on them, like sizing wax, after necking down the case, and wiping them off, thats fine with me, they dont collect dust or dirt. If I want to get every last bit of lube off the neck or body, I put a little solvent on the rag. I dont know why anyone would want the chamber to hold on the the case. When the bolt is closed, the case cant go anywhere anyway.
Mike.

[Galveston22]

There is no reason to scratch your chamber. The chambered round isnt going to move with the bolt closed. If it does, then you have got major headspace issues.

[viper9696]

I have heard that a chamber can be polished too much and you will get high pressure signs because the brass does not hold onto the chamber when it expands unpon firing and pushes back into the bolthead giving you extractor marks on the brass,I think it was a sako in a lazzeroni cal.

[Blue Avenger]

guys with brake opens may see some benefit from it.

[Salvo]

I have heard that a chamber can be polished too much and you will get high pressure signs because the brass does not hold onto the chamber when it expands unpon firing and pushes back into the bolthead giving you extractor marks on the brass,I think it was a sako in a lazzeroni cal.


That sounds familiar... It was at a benchrester's forum where I read about it. Those guys sometimes run into the effects of working too hard for perfection.

It reminds me of a story I heard about Rolls-Royce who bought the rights to an automatic transmission design from GM... There was a plate or rotor in there that the RR engineers thought was too rough, so they polished it on their version. It turned out that the roughness was part of the design though, not poor QC, and the RR prototype was a bow-wow, it didn't work well at all. Needless to say, from then on the RR guys followed spec.

This may in part explain why we can often see light tool marks in our rifle chambers, and the manufacturers do not polish them to a mirror finish.

[hotbrass]

This may in part explain why we can often see light tool marks in our rifle chambers, and the manufacturers do not polish them to a mirror finish.


Just like the rest of the gun has minimal tool marks and is not well polished, manufacturers dont polish the chamber because it is not necessary and adds cost.

Custom rifle makers and high end rifle chambers may be polished, but then again, so is the rest of the gun.

Benchrest shooters are a different breed. If the top shooter is eating a ham sandwich before he shoots, you will see them all eating ham sandwiches at the next match. ;)

[Tightgroups]

On most cases I have seen, the slope is so gradual, I doubt it would make any difference. And If there's any room behind the case head, aside from having fail to fire problems, the pressure is going to push the case back, regardless of the chambers wall texture.

[Blue Avenger]

the TC contender is noted for small base straight wall rimmed case's using the friction to there advantage. aids in keeping the frame stretch down. yet rims aid in extracting.

[hotbrass]

Thats interesting. I have been shooting silhouettes with Contenders for about 20 yrs and I have never heard of that before.

Most competitors use light loads. But I also shot 7-TCU in long range pistol and nobody ever mentioned roughing up the chamber.

Maybe its the hunters with their bottle necked cartridges like the JDJ's and Herrets. I still dont think it would help reduce the pressure on the frame.

[Blue Avenger]

I may be misleading you, I'm not saying I know anyone that is doing it. I am saying it would be a place where an off the wall thought may work. LOL the guys like me that punched .30-30s to .30-40s. went from 3"@100 to 1.5"@100. not sure if it had a bad throat before. Did know I loaded them about the same speed.

[hotbrass]

Thats a big jump. With the same load?

[Blue Avenger]

no it took more powder (4064) to get the same speed, 1800fps - super 14"
with the big foot print case head, I did not want to push it harder.
used the .30 harrett for speed.

[Tightgroups]

I'm just wondering how rough the chamber would have to be, when the case is pushed back by, say 25,000 PSI (light load) now ,pie 3.1416 X radius squared= sq" of case head??x*#&@/%, well its a lot of push, trust me :-\.

[Blue Avenger]

thinking rougher then I would ever want to make one.

[BillPa]

I'm just wondering how rough the chamber would have to be, when the case is pushed back by, say 25,000 PSI (light load) now ,pie 3.1416 X radius squared= sq" of case head??x*#&@/%, well its a lot of push, trust me :-\.


Varmint Al spent quit a bit of time on the subject.
http://www.varmintal.com/a243z.htm
http://www.varmintal.com/afric.htm

Bill

[dcloco]

Kind of odd....but I polish my chambers to prevent sticky brass and/or extraction issues.

[Budweiser360]

Most people polish/tumble their brass all the time just for the looks, it is also easier to see any defects in clean brass as opposed to dirty. Roughing a chamber with emery paper in a bolt action rifle is something that should never be done IMO. There is a reason why the most accurate rifles in the world have polished or smooth chambers...