Brass tumbling, polish, and mixed cases...

[GTOShootr]

I'll bite - how does lubing the chamber improve velocity?

The bore, yes; but the chamber?

Oh, we all know you bite.

It may be that oiling the chamber leads to oiling the bore, and causes the increase. I've heard it described as a chamber phenomenon too. Whatever the cause, it has a known outcome.

 

[Lugnut]

Oh, we all know you bite.

It may be that oiling the chamber leads to oiling the bore, and causes the increase. I've heard it described as a chamber phenomenon too. Whatever the cause, it has a known outcome.

Ever see a case with powder burn down the side? That's from escaping gases that don't help push the bullet down the barrel. That's why I'd guess a little oil in the chamber could help. Interesting though... I've never heard anyone doing that before chrono... I guess I'd rather keep 10PF cushion instead of cutting it that close!

 

[Scrivener]

Ever see a case with powder burn down the side? That's from escaping gases that don't help push the bullet down the barrel. That's why I'd guess a little oil in the chamber could help.

Powder burns down the side indicate a lack of expansion and loss of pressure, to be sure. Again, how does oiling the chamber improve case expansion?

 

[Steve_P]

Powder burns down the side indicate a lack of expansion and loss of pressure, to be sure. Again, how does oiling the chamber improve case expansion?

The oil does not improve expansion, however it could help to form a hydraulic seal for a few milliseconds and allows pressure to increase.

 

[Scrivener]

The oil notes not improve expansion, however it could help to form a hydraulic seal for a few milliseconds and allows pressure to increase.

The most logical explanation for lubing the chamber so far.

 

[noidlight]

A similar thing is done in the auto industry. If low compression is suspected in a cylinder, the technician will perform a compression test. If low compression is noted, the tech will then spray about a teaspoon of oil in the cylinder to see if the oil will take up the space between the cylinder wall and the compression rings. A second compression test is performed and the tech is looking for a substantial increase in the pressure. The oil will get between the compression rings and the cylinder wall and increase the seal of the rings to the bore. Called a "wet compression" test, if the pressures rise substantially, it indicates worn piston rings. Little or no change indicates good ring sealing.

So I can see what Steve is talking about and how putting oil in the chamber can actually seal it to ensure all gasses exit the front of the barrel behind the bullet. Cool trick, I never knew that.

 

[GTOShootr]

The most logical explanation for lubing the chamber so far.

I believe it to be the hydraulic seal as well since messing with chamber pressure can be demonstrated to affect velocity with another chrono trick. A very experienced shooter showed me that if you shoot your 1911 off a rest over the chrono but you rest the gun on the front of the slide, not the dust cover, it will induce an ejection malfunction but you'll get higher readings. The unlocking of the barrel is slowed with the drag on the slide, bascially creating a single shot, and the condition results in a small increase in velocity.

 

[jar]

I separate all my brass by caliber then de-cap and resize my brass first.
Then ultrasonically clean in a mixture or 50% Water, 50% White Vinegar. And sever drops of Dawn Dish Detergent.
I dry the brass in my dryer in a leg from a pair of jeans tied at both ends. I toss in 3 or 4 old towels to reduce the noise.
.
Then I put the brass in a vibratory tumbler.
My tumbling mix is as follows:
60% White Rice, 40% Lyman Red Rouge Coated Corn Cob Media (let that tumble around for 1/2 hour and the rouge disperses to all the rice).
I mist a bit of Kroil on the media and let it mix up real good (just a couple of mists over the top surface and let it roll for a bit, 2 or 3 times)
(OK, why white rice you say? It's pointy at the ends and gets pointier as you use it. It cleans into corners exceedingly well)
.
Put brass in tumbler after wards and let it go overnight.
The brass comes out like you polished it on a cloth wheel, inside and outside, primer pockets too.

Wow, that sounds like way too much work. Is shiny brass really worth doubling your reloading time? (Roughly, since you run everything through the press twice)

 

[rattletrap1970]

Well, not really through twice, just on that one station. I back the decapper out and just run them through a Dillon 550. It's just makes it 1/5 more time. I only go though all that when I get brass from the range. Once it is nice and clean, it stays pretty good for a couple firings. But if you are using range brass it can have sand, spiders, webs, cigarette butts, who knows what in it. So it's spotless once it's mine.

 

[DukeInFlorida]

Mine goes through the press once. I polish with the primers in place.

(If it's mil crimped, then that gets taken care of elsewhere, and then run through the press for final assembly.)

 

[swampy]

Ah, the sweet smell of sassafrass. Simple green is awesome. I use it as an air freshener at work. Ain't never tried it to clean brass cases. I've been looking for a tumbler large enough to drop my harley in to polish it. If anyone should see one ... I'm sick of hand polishing that thing. Those solid wheels can single handedly suck up and retain all the brake dust ever made in the world. I like polishing brass...separate it and toss it in the tumbler, when the harley is cleaned and shiny its time to load up a new batch of brass in the tumbler.

Before I bought a tumbler I used "Simple Green" on my brass to clean it. Used hot water to start with in the mixture and rinsed it with hot water after letting it sit for a couple hours. It got the brass pretty clean but *NOT* nice and shiny. The shiny part did not bother me. It was the smell. Actually the smell is what my wife hated. She would walk into the basement and smell Simple Green and hate it. A good enough reason for me to buy a tumbler. I'v only been using the tumbler now with Corn Media.

Question... Why 60% white rice? Does it work well?

My wife is Korean. She loves her rice (sorry but she does, not trying to be racist here). Anyway, I'm sure she would not be happy with my dumping rice into my tumbler but it sounds like an interesting experiment. I have a couple 50 pound bags of the stuff laying around here somewhere.

 

[EddieCoyle]

I don't care how shiny my brass looks.

There are only two tangible benefits attained by tumbling the brass. The most important one (and the one you don't get using your method) is keeping crap out of the sizing die. The second is that it makes the cases easier to inspect.

I separate all my brass by caliber then de-cap and resize my brass first.
Then ultrasonically clean in a mixture or 50% Water, 50% White Vinegar. And sever drops of Dawn Dish Detergent.
I dry the brass in my dryer in a leg from a pair of jeans tied at both ends. I toss in 3 or 4 old towels to reduce the noise.
.
Then I put the brass in a vibratory tumbler.
My tumbling mix is as follows:
60% White Rice, 40% Lyman Red Rouge Coated Corn Cob Media (let that tumble around for 1/2 hour and the rouge disperses to all the rice).
I mist a bit of Kroil on the media and let it mix up real good (just a couple of mists over the top surface and let it roll for a bit, 2 or 3 times)
(OK, why white rice you say? It's pointy at the ends and gets pointier as you use it. It cleans into corners exceedingly well)
.
Put brass in tumbler after wards and let it go overnight.
The brass comes out like you polished it on a cloth wheel, inside and outside, primer pockets too.

 

[Lugnut]

Wow, that sounds like way too much work. Is shiny brass really worth doubling your reloading time? (Roughly, since you run everything through the press twice)

I like clean brass too.. but I let the tumbler work twice as hard- not me! You'll never see me put any brass in my dryer, dishwasher or washing machine either. Only brass that the wife finds in the dryer is an occasional round or two that I forgot to take out after practice.. man does that piss her off. They still go bang too!

 

[Scrivener]

You'll never see me put any brass in my dryer, dishwasher or washing machine either. Only brass that the wife finds in the dryer is an occasional round or two that I forgot to take out after practice!

Roger that.

And untumbled brass NEVER touches my dies, just as oil never touches my media.

 

[Gammon]

I used to have a great book on progresive reloading by a guy named "John Paul Jones". I loaned it out to all of my friends and somebody forgot to return it. Too bad because this little volume was a wealth of information. I remember his tips on case cleaning. He was dead set against any form of detergent or chemical/water cleaning. His point was that you didn't want to get the cases "too clean". Chemical and detergent/water cleaning tended to remove all of the oil and made the cases extremely hard to resize, while tumbling left a small residue of oil which made resizing much easier. Food for thought.

 

[sieveboy]

With all the correction going on, I figure it's OK to mention that the tendency of a substance to attract water is called "hygroscopicity". "Hydroscopicity" is not a word.

 

[Kenny474]

While I do deprime my brass prior to tumbling, I do so with a separate depriming die and I don't load a ton of ammo so it doesn't take me that long. I am not a fan of dirty brass in my sizing die, and a depriming die is only $10 or $15 so it makes far more sense to buy the die than scratch or muck up my sizing die.

Rattletrap, if you are going to deprime before tumbling maybe a depriming die would be a good purchase? $10 is a lot better than damaging your sizing die.
http://www.midwayusa.com/viewproduct/?productnumber=136543