Fired brass with oil on it. I'll bet you've all done it after resizing....

[DukeDuke]

I use carburetor cleaner to get the lube off my sized brass. Mean stuff to work with, but it sure does the job! Oily cases do a lot to increase back thrust on a bolt's locking lugs.

and evaporates fast.

 

[spife7980]

I'm not understanding the logic behind cratering and sizing lube. Can someone explain how the two are related?

Im going to venture a guess.
I would think that the lube takes up volume inside the chamber and that can cause an increase in pressure. Maybe that increase in pressure is enough to start the primer flowing back?

The lube on the cases could also prevent the brass friction from sealing all the way up against the walls of the chamber and instead wanting to slide back a bit more allowing an increase in bolt thrust. Now that relates to cratering of a primer Im not sure but if could definitely increase the rearward forces in the chamber.

 

[ChrisA]

Probably excessive but I rinse sized brass in hot water and dish soap then rinse in clean water, then Iosso brass cleaner treatment.

I run Hornady One Shot lube.

Only downside is waiting for brass to dry but I speed up by setting next to dehumidifier's warm air.

I only do this to have clean brass in the chamber, not because of pressure issues

Chris

 

[rammac]

Yes, just looking for a fast solution to the sizing oil. How do you do it?

I use the Hornady ultrasonic cleaner and their cleaning fluid. I use Imperial Wax and after a 20 minute cleaning my cases have no lubricant left on it.

 

[rammac]

Lubricant on the outside of a case can increase bolt face pressure by a substantial amount. I've seen arguments about exactly how much but in any case there is a possibility that bolt face pressure could increase by at least 30%.

The chamber of a firearm is designed to have a certain amount of surface roughness so that there will be some amount of friction between the cartridge case and the chamber walls. The friction is designed to hold the case in place when the burning powder expands the brass. When the case is held in place then the case head stretches until it contacts the bolt face. The head contacting the bolt face produces a certain amount of pressure. If the case has lubricant on it then the case can slip back toward the bolt face which will result in higher pressure on the case head/primer/bolt face. That higher pressure can cause the primers to crater since they will be driven in to the bolt face with greater force.

 

[Colt Kodiak]

Lubricant on the outside of a case can increase bolt face pressure by a substantial amount. I've seen arguments about exactly how much but in any case there is a possibility that bolt face pressure could increase by at least 30%.

The chamber of a firearm is designed to have a certain amount of surface roughness so that there will be some amount of friction between the cartridge case and the chamber walls. The friction is designed to hold the case in place when the burning powder expands the brass. When the case is held in place then the case head stretches until it contacts the bolt face. The head contacting the bolt face produces a certain amount of pressure. If the case has lubricant on it then the case can slip back toward the bolt face which will result in higher pressure on the case head/primer/bolt face. That higher pressure can cause the primers to crater since they will be driven in to the bolt face with greater force.

I think that makes a lot of sense. Brass expands against the bore and if there is oil (or wax), that would change. Shooters should make sure there is no sizing oil or wax on their brass before firing. (period, and in my opinion).

 

[tomswede]

If you have a tight chamber bolt thrust will be the same with or without lube on the case. Having a lot of head space case stretch ( and the resulting reduction in case life ) will reduce bolt thrust. The rifle should be designed to take the full load and not rely on the case stretch. For test data see Rifle Accuracy Facts by Vaughn.

 

[Colt Kodiak]

If you have a tight chamber bolt thrust will be the same with or without lube on the case. Having a lot of head space case stretch ( and the resulting reduction in case life ) will reduce bolt thrust. The rifle should be designed to take the full load and not rely on the case stretch. For test data see Rifle Accuracy Facts by Vaughn.

Good to know. Thanks

 

[BoydAllen]

Real world situation: A friend would get pressure signs on his case heads the first couple of shots after cleaning. The rifle is a slow twist 6BR chambered for Lapua brass. He was getting ejector marks with the same load that would normally not give that, and did not after a couple of shots. The problem was that he was using, and reusing a chamber swab to wipe his chamber after cleaning, which was leaving solvent on the chamber wall. He was cleaning with Butch's. The bore was dried with several dry patches. When he changed to a different procedure that produced dry chamber, the problem went away. This fellow knows how to set a FL die, and shoots very well. Draw your own conclusions.

 

[Longtrain]

FWIW, I make sure my cases are clean and dry. I use Imperial and if I'm only resizing a few (50 or less), I just wipe them with a paper towel. Usually I collect my fired brass and do mass resizing 2-300 pieces at a time and toss them in the SS Pin tumbler for 30 minutes with hot water, a bit of Dawn and a sprinkle of Lemishine. Never had a problem either way.

 

[tomswede]

Real world situation: A friend would get pressure signs on his case heads the first couple of shots after cleaning. The rifle is a slow twist 6BR chambered for Lapua brass. He was getting ejector marks with the same load that would normally not give that, and did not after a couple of shots. The problem was that he was using, and reusing a chamber swab to wipe his chamber after cleaning, which was leaving solvent on the chamber wall. He was cleaning with Butch's. The bore was dried with several dry patches. When he changed to a different procedure that produced dry chamber, the problem went away. This fellow knows how to set a FL die, and shoots very well. Draw your own conclusions.

The pressure is the same, the load on the case head is lower with load sharing with the case ( Hookes law) when it grips the chamber walls. Sized for zero head space the load is the same, lubed or not.

 

[M-61]

I recall a post by bigedp51 quite some time ago however I can not find it at all maybe due to the change on the sites format a couple of years ago.
I think he had made reference to 'oil' regarding 303 British and the proofing of fire arms by the Brits. It roughly said that after various increases in the load the final 'proof' was to oil the case and fire it. If it held up to that it declared OK.
Don't think I have it wrong and having him show up here to correct or confirm my recollection would be nice however unlikely. Maybe someone else can fill this in.

 

[BoydAllen]

The pressure is the same, the load on the case head is lower with load sharing with the case ( Hookes law) when it grips the chamber walls. Sized for zero head space the load is the same, lubed or not.

Like I said, real world. We do not size for zero clearance. No one that I know does. That was my point. We build our loads to achieve results not to duplicate conditions necessary to meet the requirements of a law. Cases do not size uniformly, so we push shoulders back enough so that they will function uniformly despite these differences and the reason that we do that is that if rounds chamber differently accuracy suffers. You can shoot tight with tight, and loose with loose, but if you mix them the results will not be as good.

 

[BoydAllen]

https://en.wikipedia.org/wiki/Bolt_thrust

 

[rammac]

The British used oiled cases to proof test their cartridges in all of their firearms. The idea being that the oiled cartridge would slide backward and put full pressure on the bolt face. They placed a copper crush washer between the case head and the bolt face with a hole in the washer for the firing pin to go through. The washers were calibrated to compress a specific amount for a specific pressure. After firing they would measure the thickness of the washer and that would tell them the pressure that the powder charge was producing.

 

[Brians356]

I use mineral spirits on a rag to remove die wax. Works like a charm and a lot less rubbing than with a dry rag.

How much wax do you need to remove, anyway? I use the absolute minimum, and a dry rag or paper towel wipes off what's left afyer sizing in two seconds. If I had to break out the smelly stuff, it would make me take up golf again. But if I had to, I would use plain ol' isopropyl alcohol.
-

 

[Brians356]

I use carburetor cleaner to get the lube off my sized brass. Mean stuff to work with, but it sure does the job! Oily cases do a lot to increase back thrust on a bolt's locking lugs.

You're overthinking this, you really are. That's nasty stuff, and soooo unnecessary.
-

 

[Colt Kodiak]

I clean my brass with 99% isopropyl alcohol.
IPA is used in most high tech industries for cleaning product and work surfaces. Includes aerospace, electronics, medical products and semiconductors all of which need to be cleaner than your cases.

Where do you find 99% isopropyl alcohol? I can only find 91%.

 

[bigstick6017555]

if you are using imperial sizing wax the way it is suggested to use, there is no need for any type of liquid. a clean dry rag is all that is needed

 

[Milo 2.0]

Where do you find 99% isopropyl alcohol? I can only find 91%.

Amazon your best bet, stuff is expensive, just buy a gallon of denatured alcohol from your local Menards or Home Depot. Trust me, the outside of your brass can handle a few impurities.
Now if you're making homemade case lube, you want the 99% pure.