When you fire your first round with an oily chamber, the POI at a 100 yards can change to 5 inches high and most of the time, 1 to 3 inches to the right as well. This effect will be even stronger when you shoot thru a barrel which is not totally oilfree. What makes oil around the case in the chamber, even if there is no significant headspace, so tricky?

I always dry patch my rifles before shooting them for the first time after cleaning. It makes a big difference. A bonus result is that the gun vise is already set up when I get home so there is no excuse not to clean the rifle(s) immediately after a range session.
Pete

An oily chamber can be dangerous.
When a cartridge is fired, the case expands into all directions. If there is oil between the case and the chamber, there is no friction between these and the total amount of the recoilforces goes back on the bold or the breech.

The danger with an oily chamber is that oil around the case neck will prevent the neck from opening rapidle. The thrust against the breech is the same oiled or not.
Good luck!

...Also oil will not compress so pressures go up…. It’s a good Idea to keep your chamber oil free.

If I do not do a good job of removing the oil from the cylinder of my revolvers, high pressure loads cause the brass to slide back. This makes the cylinder progressively harder to rotate. It has never locked up my cylinder, but reports indicate that it can.

The same phenomina happens in rifles...the brass slides back rather than holding a porion (small but possibly significant portion) of the chamber pressure. Dry chamber==case stretch (high resistance), oily champer==case slide (low resistance) making the pressure on the bolt higher.

Modern bolt actions with sane loads should never know the difference...marginal loads might go over the top from it. YMMV. Why take the chance...

how oily is oily?.....you mean dripping in oil?..

A thin film is not a problem at all but not the way I want to leave my gun.

Clean the gun at the range and fire it and then bring it home. Then next rounds you fire then will be from a fired barrel and not one with an oil film.

There's no reason at all to leave your gun bore with an oil film!

There is this confusing myth on oiled cases and rifles. This myth started in a book titled “Hatcher's Notebook†by J. S. Hatcher in the section dealing with the 1921 Tin Can ammo. The tin on the bullet jacket cold welded the bullet to the case neck. This created a bore obstruction. A number of rifles were ruined at the National Matches. The Ordnance Department who supplied the ammo, decided to shift the blame to the shooters by blaming an operational practice of the shooters.

They found a unique practice at the time, shooter’s were greasing their bullets to reduce copper fouling. Ordnance claimed that was the reason the rifles blew up. They concocted reasonable sounding theories (all ignoring the bore obstructions that cold welding created) and ran rigged pressure tests to prove their case. Greased bullets were banned for more than 50 years at the National Matches until the original reason was forgotten.

I think the millions of Moly Lubed bullets fired down range have somehow proved the Ordnance theories and tests as bogus. Being a good Ordnance Department Officer, Hatcher reported the theories and failure analysis uncritically. Somehow people reading his book did not see the inconsistencies, and confused greased bullets with case lubrication. This confusion was codified, repeated as fact, time and time again by Gunwriters of the 1970’s and has become a “cultural memory†in the reloading community.

No action is designed assuming that the case provides any friction or carries any load. Take a look at the calculations on Lija’s page and at the article bolt lug strength. http://www.riflebarrels.com/articles/custom_actions/bolt_lug_strength.htm.
In fact it is it is a shame that the case does stick in the chamber. It would be far easier to design an action where there was no primary extraction force required (while retaining the gas sealing effect of the case). As it is, breech friction is hard to design away. In one action, the G3 rifle, the forward ¾ of the case is floated by gas lubrication to prevent the case from sticking to the chamber walls. If it were not so the case rim would be ripped off upon extraction. Blowback cartridges usually have a polymer coating on them. Steel cases are lubricated by paint or copper wash to prevent them from sticking to the chamber walls, and chambers are often chrome plated to reduce corrosion and to reduce the friction between the case and the chamber walls.

I highly recommend visiting this site and seeing a dynamic analysis of chamber finish/case fricition. http://www.varmintal.com/a243z.htm What I want to point out is that as case friction is reduced, case stretch is reduced. If this is true, it may mean that that cases are less likely to rupture, either through a brass flaw, or through repeated firing, if the cases are lubricated.

I agree that pinching a case neck or preventing the case neck from expanding will increase pressures. However, try to measure the film thickness of a thin coating of oil. I have tried, and I can’t. I have fired cases that had paste wax rubbed on them, cases that I left the sizing lube on, and I have found, after firing, no difference in case neck expansion between them and a dry case. The film thickness is smaller than the measuring capabilities of my home gages.

This might be of interest on this topic:


From Army Material Command Pamphlet AMCP 706-260 Engineering Design Handbook, Guns Series Automatic Weapons. Feb 1970


Chapter 8 Lubrication of Machine Guns

8-3 Case Lubricant


Although the gun designer is not directly involved with ammunition design, he is directly concerned with handling, loading, and extracting during firing. A smooth chamber is essential for extraction and a properly lubricated case is a decided asset. The lubricant should be a dry lubricant and should be applied at the factory. Considerable effort has been made to find suitable lubricants for this purpose. Some success has been achieved but continued search is still being advised, especially since two independent facilities are not in total agreement.

The Naval Research Laboratories conducted test of brass and steel cartridge cases coated with films of polytetrafluoroethylene (Teflon). Results were outstanding in meeting required protection and lubrication properties. Laboratory results, later confirmed by firing tests, showed low friction and consequently less wear in gun barrels. Other desirable features include freedom from cartridge malfunction, no chamber deposits, decreased ice adhesion, and less chance of thermal “cook-offâ€. Teflon can be applied to steel and brass ammunition by mass production methods. Its protective ability permits pre belting and packaging of ammunition since no further handling prior to use necessary. Its supply is abundant and its cost reasonable. Thus the use of Teflon in this capacity seems ideal.

Aberdeen Proving Ground is more reserved in its appraisal of Teflon coating. Whether or not the techniques of applying the coatings were similar, those used at APG were not free of coating defects; a high cull rate existed. When tested with cartridges coated with microcrystalline wax, ceresin wax, and uncoated ammunition; the Teflon-coated wax showed many advantages but was also found wanting in some respects. Teflon and micro-wax had better extraction properties and Teflon left a much cleaner chamber than the others; micro-wax was second best. About 50 percent of the Teflon-coated cases had slight bulges after extraction; other types also were similarly damaged but with no apparent significance attached to a definite choice. For dusted ammunition, the Teflon and micro-wax were far superior to the other two types with Teflon having a slight advantage, although when fired in a comparatively rough chamber, Teflon was outperformed by all. Reiterating, the gun designer, aside from providing smooth sliding surfaces, is almost totally dependent on the physical properties of the lubricant to make his gun perform satisfactorily under all assigned conditions.

The last sentence is a summary of the chapter; not a comment on case lubrication alone. A copy of AMCP 706-260 and other out of print AMCP pamphlets can be ordered from NTIS at 703-605-6000.

Thank you folks, for your input. Perhaps I did not state my question clear enough, sorry for that. I read an article in which the author said that with a film of oil in your chamber and/or barrel (not dripping, vapo!), the shift of the POI at 100 yards (or meters) could be considerable up and to the right, see head of this topic. I am aware that many hunters think it normal to dry the chamber and barrel (as do I), be it, the input of Slamfire was real interesting and gives some other ideas on lubricating, greasing and coating. Thank you Slam, I read your post three times and visited the sites you recommended. And thank you Reindeer, funny to read your comments living just nextdoor!
I did some testing with my .270 Winchester as well, with AccuBonds 140grainers. I noticed the same POI-shift as in that article. But the author gave no explanation, only what happened. Interesting was, he found a shift up and to the right for a boltaction .22-250, .30-06 and 9,3x62, a doublebarreled Blaser 6,5x57R and a 'drilling' Krieghoff 7x65R. My question again: why does this happen, all going up and to the right.? More or less pressure and/or velocity? Variables as in load development? Could the optimum barrel time have changed and be of any importance? And if so, why only this same shift in all the rifles?
Nice day, Jan.

It is not possible for the neck to expand as quickly if it is coated. The oil has to extrude
before the neck can expand. Checking the neck diameter will not tell you when it expanded.
A case in a dry chamber will be pushed forward by the primer. It will stay forward until the pressure reaches 40 kpsi or some such. That is why light loads will have projecting primers when fired in a chamber with headspace. A light
coat of oil will allow the same case to move back, and the primer will look normal.
It's interesting that you feel obligated to call Hatcher a liar. As to the "soldered bullets" the pressure in the case would expand the neck away from the bullet. A pull test would nt inducate anything.
Good Luck!
Good Luck

Oil is incompressible. Under pressure, excess oil in the chamber and/or bore can have disastrous results. Because I periodically see the results of guns being fired with oil, moisture or spider webs in the bore, I make it a personal habit to run a bore snake through the bore prior to taking ANY rifle into the field. Why chance it.

I don't understand how the neck can expand away from the bullet when the bullet is blocking the action of the expanding gas from forcing the neck against the chamber wall. It has always been my understanding that the bullet has to move out of the way before the neck can fully expand.
I would like you to perform an experiment! Solder a bullet into the case and fire it, then report the results. You can do it by glueing in the primer, (To seal it.) using a load that does not fill the case, submerge most of the case in water and use a soldering iron. Make sure to tin the bullet and inside of the case mouth before loading so the solder takes.
Do I have any takers on this?

For years now I have been firing my Match M1a's and Match Garands with "lubricated" cartridges. I apply Johnson Paste Wax and buff the stuff off. This wax melts under the pressures and temperatures of combustion and acts as a lubricant.

The reason I do this is to increase my case life. The normal lifetime of a case fired in a M1a is between five and ten reloads. The typical failure mechanism is case head separation. I have taken one set of LC brass to 22 reloads in match M1’a without any signs of case head separations. I have had expanded primer pockets, cracked case necks, and brass splits. All of which are to be expected as brass is used and work hardens.

I got the idea from a gunsmith who is a Distinguished HM with the M1a. He gave me this advice. And like the typical customer who had been raised on the gunwriter created “myth of the lubricated case†I thought he was nuts. However he was right, a normal spec load does not damage the rifle, does not effect accuracy (in a front locking mechanism), and increases the case life beyond normal practice.

His practice was to leave RCBS case lube on the case. He never tumbled his cases, just lubed them in a lube saturated towel, sized them, primed them, and shot them. Since he won every medal (expect President’s 100) that you can win in Highpower with this ammo, and wore out a barrel a year shooting this stuff, such direct evidentiary data is better than literary philosophizing.

I did try leaving RCBS case lube on, and found that I did not like sticky cases that would pick up dirt. So I use a dry lube. Paste Wax. Incidentally the amount of RCBS case lube just left the case feeling slightly greasy. I suspect the film thickness was in the ten thousands of an inch. It does not take much lube to get lubrication.


The Garand type mechanism is very hard on cases, but I do not lube cases in bolt guns or AR’s. There is no need, case life is acceptable.

I will say that the first shot out of an oiled barrel, or a clean barrel is always (or almost always) at a different location from a fouled barrel. I have started many a 1000 yard match with the exact same sight settings as I finished the last, using the same lot of ammo, and the first shot is never anywhere near the center. At the end of the match, the sight settings are always close to the previous match. Just little differences due to wind and temperature, and how I hold the rifle.

As for Hatcher being a liar. I said he reported uncritically. This is not as nasty as calling him a liar. If you read his section in his book, one fired bullet was picked up that still had the case neck attached. Obviously the Tin Can ammunition was not working predicatable.

This is not meant to be a dump on Hatcher, but if you notice Hatcher never expressed a strong negative opinion in any of his books. He never criticized any policy or decision made by the US. Army, a Military leader, or the Ordnance Department. The only light criticisms were against people outside of the Military. By and large Hatcher was a very “positive†writer. Learn from this. Hatcher made Major General. Captain Crossman, an acerbic, gunwriter from the same time period, never made it past Major.

quote:

Originally posted by SlamFire:
So I use a dry lube. Paste Wax.

I use Flitz

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=752367

it puts a slick finish on the brass and makes it more resistant to fingerprints, weather, loop type ammo carriers etc.

It really puts a shine on the case

flitzed case on left............new unfired case on right




slamfire, it seems you are well informed on this subject, I would appreciate your opionion.

Jan
I think the answer to your question might be the difference in barrel transit time.
With lubricant in the bore a bullet's time in the barrel is different than a "dry" bore(all be it a very small difference.) This different transit time means the bullet leaves the barrel at different points in it's vibratory motion(most often described as a figure eight).Hence a different point of impact.

muck

quote:

why only this same shift in all the rifles?

Thank you Muck, we're coming closer. If you're right, one could find the shift all over the target. Not so. Why?

My guess is that an oiled case will impact against the breech earlier in the discharge. Resulting in a different force into the receiver.
It is the flexing of the receiver that causes
"barrel whip", and a different exit direction for the bullet. For a full explaination check
"Rifle Accuracy Facts".
Good Luck!

Military training from early in the 50's through to the early 80's dictated a dry breech (which doesn't stay that way in SLRs) and which I still practice today. Of course initially; and now, this principal referred to the 303. What an intelligent design for a military round, tne taper of the case ensures positive extraction every time which almost; but not quite, makes the large rim and extractor redundant. Topped off with the MkVII pill, Ah perfection.

Woods; Most polishes are solvent based. I have Flitz at home, use it for polishing steel knife blades. I am quite certain that with the abrasive in the polish, when the solvent evaporates, Flitz will leave a thin coat of wax on the surface. That would explain the shine and the surface protection.

I am of the opinion that some Factory cartridge cases are dipped in a wax solution before shipment. I cannot say it is true for all factory cartridge cases, but I have noticed on old Federal, Remington factory ammo that I purchased in 1983, strange spider webbing tarnish. I believe the cases have maintained a overall shiny finish due to a protective wax coating. And that the spots of tarnish are consistent with corrosion occurring under the wax. It would make sense, people want to buy shiny ammo, and vendors would not be happy if their inventory turned dark brown.

Somewhere in Hatcher’s text book of Revolvers is a statement that the .276 Pederson was coated with wax, and unless someone told you, you would not know.

Let me make a disclaimer: Reducing the friction between case and chamber does increase bolt thrust. I am only doing to increase my case life in one type of semi automatic mechanism. I do not fire maximum loads. I fire loads that give excellent accuracy and 100% function reliability. My loads in the M1a give a 168 Sierra Match Bullet a velocity between 2550 and 2625 fps. Commercial ammo tend to be much faster (like 150 to 200 fps) and therefore higher pressure. Many people also create loads that push the pressure envelope. Reducing case friction on a load that exceeds SAMMI specs will stress the action. It will really spring a rear locker like a Lee Enfield.

I really do not recommend using lubricated cases in bolt guns or single shots. Except I am doing it with my Swiss 7.5 cases. I purchased 1000 new Swiss boxer cases at a hideous price. And the stuff is a little short, headspace wise, for my rifle. Well I don’t want case head separations on the first shot. So I have rubbed paste wax on the cases and the stuff is doing well. What is happening, is that the case slides to the bolt face instead of stretching to the bolt face. And that, increases my case life.

Slamfire, We are almost together on this.
The case will stay forward until somthing in the range of 40kpsi, that is why spring is avoided in the Lee Enfield. The same effect can be noted with other "springy" actions such as a rolling block. With your Swiss, lubrication allows the case to come back at lower pressure then expand forward avoiding the "stretch ring". Ackley fired a 94 Winchester without locking lugs. The the action stayed shut, he attributed it to the "Improved" 30/30/ .
If he had oiled the case, or raised the pressure a bit it would have been a different story.
Good luck!

Hope it was an interesting read.

Best Regards, SlamFire

Malm, you are a true benefit to AR, I personally learn much from your posts, and always look forward to your posts and the experience that comes through them.
I need to quit procrastinating and send you my BLR's for trigger jobs, then I can experience some of your experience--first hand.

Thanks--Don