While this is not a "reloading" query, it approximately fits the forum. Were Johnson's Paste Wax put on the cylindrical part of factory 44 Magnum ammunition brass, will there be a large increase in chamber pressure when the cartridge is fired?

I think you are asking if polishing the exterior of your cases with paste wax will increase the pressure generated by ignition. If I have this right, my answer is No because the charge is inside the case and the wax on the outside alters the combustion of the powder not at all. Another concept is if the paste wax will cause a decrease in the "airgap" around the case when it is inserted in the cylinder, which would cause an increase in pressure inside the case because there is less volume into which the case can expand as it fires. Again my answer is No because the thickness of the wax coating is negligible. Try measuring a case, waxing it up and measuring it again. My guess is you will find less than .001 inches difference...

Lubricants (of any kind) do not increase the chamber "pressure", but they can / do increase the "bolt thrust" (rearward force) by reducing the grip the case has on the chamber wall.
How much of a bolt thrust increase there will be depends on several things, but it is higher in a tapered case than it is in a straight wall case.

quote:

Originally posted by Tailgunner:
Lubricants (of any kind) do not increase the chamber "pressure", but they can / do increase the "bolt thrust" (rearward force) by reducing the grip the case has on the chamber wall.
How much of a bolt thrust increase there will be depends on several things, but it is higher in a tapered case than it is in a straight wall case.

the 44 being a straight wall case,I dont think it will make much difference.Also,Im not sure if wax will make a difference.PO Ackley used oil to increase the bolt thrust with tapered cases,IIRC it(oil) didnt make alot of difference with minimum taper cases,which were ,of course,the "improved case form".Give it a try,and let us know.

As most everyone knows I use BoeShield T9 lubricant for sizing lube a little goes a long way .

If any of you are familiar with this product you will know it leaves a waxy residue or waxy film to be

correct . I've been using it for better than 20 years now and have yet to experience a single negative

side affect . Keeps cases cleaner longer easier chambering and extraction it also retards brass tarnish

for extended periods . Now I do wipe my my cases and cartridges off prior to box storage ,so the only

thing left is that ultra thin wax film . Like the handle says 224/375 an nearly everything in between .

Including pistol cartridges .380 9mm .38 .357 44/40 .44 .45 .45LC .

So I'd have to say including Rifles maybe #40-45 cartridges and have yet to have a single problem .

I learned many many years back not to " Proof Load " my rounds , that's what they make test barrels

for and the personnel running those test .

deleted

In a higher pressure cartridge the case comes
back with the same force lubed or not.
Do you really think that firearms are not
designed for "case thrust" ?.
Good Luck!

deleted

quote:

From the Taurus revolver manual-
quote:
8. Do not oil cartridges, and be sure to wipe the chamber clean of any oil or
preservative before commencing to shoot. Oil interferes with the friction
between cartridge case and chamber wall that is necessary for safe
functioning, and subjects the firearm to stress similar to that imposed by
excessive pressure.


From the Speer reloading manual #13 handgun section p.440-
quote:
If not removed, the lubricant on the case can cause extra strain on the firearm because the case won't adhere to the chamber walls during firing and will thrust harder against the breech

I am confident to say that none of the writers of this material actually have any data to back up their statements.

Lubricated cases are un necessary in manually operated firearms. However for semi automatic mechanisms, lubricated cases enhance function as breech friction is reduced.


I have been using lubricated cases in my M1a’s and M1 Garands for well over 20 years. I got the idea from a Distinguished HM gunsmith who told me he was able to shoot in his M1a, a set of 308 brass for the season.

He was right. He left RCBS water soluble lubricant on the cases, never removed the stuff. I did not like that as it was greasy and attracted dirt.

I put Johnson Paste wax on my cases. Buffed the rapid fire cases. You could not tell paste wax was on the unfired rounds.

I took a set of lubricated 308 cases 22 or 24 reloads without a case head separation in my M1a. My case life would have been around 8 if the cases were left dry.

If there are any pressure issues, it will be due to over pressure ammunition. Not case lubrication. 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/ar...olt_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.


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

quote:

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-off”. 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.

Incidentally, how do you know that your factory cartridges don't have a wax coating?

I have some old factory cases that are exhibiting a spider web corrosion. This sort of corrosion pattern only occurs under a film.

It makes sense for manufacturers to dip factory cartridges in wax to slow case tarnish. People, and retailers, want shiny cases.

And you would never know.

Probably been shooting them all the time.

quote:

Originally posted by jb:
...the 44 being a straight wall case,I dont think it will make much difference....

it does seem that way, yet we do get case head separations, which result from axial stretching.

I guess that's why reloading is interesting, not boring.

quote:

Originally posted by SlamFire:
* * *
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

MGs are different. primary extraction has long been a problem with MG design. that's why the japanese had oilers on some WWII MGs. the italians, too, IIRC.

deleted

The case stays forward until a given pressure.
Then it either comes back, or the forward part
sticks and the rear comes back stretching and
thinning the case. Once the case comes back it has the same force oiled or not. This has been
verified by Finite Element Analysis,and measurements.
At lower pressure the case stays forward and the primer projects out. You see this in lower pressure rounds with some headspace.
When the case comes back a projecting primer is forced back in giving the "rivet" look.
In a revolver if the case is not free to
move after firing it will lock the cylinder.
Good luck!

Jib Jab back & forth too & fro .

Normally persons who touch cartridges leaves a oily film from their fingers , IE finger prints Eh ! .

so if one was fingering the cartridges before chambering will the revolver fail NO !.

Now if you soak a cartridge in 90 weight gear oil and don't wipe it , yea you're going to have a problem !.

A wax film is insignificant . That doesn't mean putting paste wax on a cartridge and leaving the

residue on it without wiping it down , so as to only leave the protective film .

How many wax their vehicles and leave the residual on with out wiping them off ???.

Use Common sense !.

You are right Doc, the back and forth isn't worth it. I deleted my posts and guess everyone should just grease up their cases like the prototype CETME's before chamber flutes and have at it.
I will suggest that it is very easy to email the manufacturer of a firearm to get their opinion on such subjects as they will be the ones to grant or deny warranty repair if necessary.

quote:

Now if you soak a cartridge in 90 weight gear oil and don't wipe it , yea you're going to have a problem !.

I have not used gear oil, but I have coated 30-06 cases with 10W-30, fired them, and the world did not end. My ammunition was not a maximum or over max load.

quote:

A wax film is insignificant . That doesn't mean putting paste wax on a cartridge and leaving the residue on it without wiping it down , so as to only leave the protective film .

Insignificant in what way? A little lubrication goes a long way.

In my experience, dry cases fired in my M1a showed flattened primers. Paste waxed cartridges, wiped or not, had nice rounded primers.

So do dry cases create more pressure than lubricated cases, or is something else going on. ?


How the G3 reduces breech friction.



Yes, machine guns are different. They have to be built heavier for thermal issues and they are expected to fire a heck of a lot more rounds between rebuilds. Still, the operating principles are the same.

From Col Chin’s book on the Machine Gun:

yes, they are different, in their primary extraction. as in, a lack of it.

how many modern MGs oil the cases?

I can't think of any modern machine guns needing oil on the cases. I heard from someone who was at the testing of the Sergeant York, that the German competitor had a guy spraying oil on the cases to keep their mechanism going. When that was found out, it was disallowed.

Breech friction will defeat all automatic firearm mechanisms. (Thermal is an issue too, but if you don’t overheat the mechanism, breech friction is the next thing that will stop it.)

Oils are messy and modern designs have eliminated the stuff. If you get a copy of Col Chin’s book, Vol IV (going rate is about $250.00 right now), you can read the discussion on the wide variety of design mechanisms, and their pluses and minuses.

I lubricate the cases on my M1a (and M1) because these cases are expensive. When I can take my cases 22-24 reloads without a case head separation, that is a cost saver for me.

Others who have deeper pockets can run them dry, and replace them in 5 to 8 reloads.

Slamfire; Right on, you are allowing the case
to come back and expand forward evenly. This avoids the "stretch" line.
Good Luck!

FWIW...I haven't read any actual "scientific" case studies or test done under laboratory conditions and only a few "I did this... and got away with it".

Whatever you do...it's YOUR weapon and YOUR responsibility...if you want to try out something you read on the web...have at it.

I use oiled cases to fireform most wildcats I build using a relatively low pressure charge(30-35KPSI)...I use Imperial wax to size cases...been doing it for over 50 years...AND...it is almost impossible to remove wax residue without a bunch of work.

I've only blown up a couple actions...by design...and I'm still here doing the same thing but always using a bit of common sense which is all but impossible to teach in todays "technofreak" world.

My sage advice is always follow the fine print...it is there to try to keep idiots from getting killed off.

The rest is just whizzing in the wind, whiskey talk around the campfire and boys comparing their measurements.

Happy New Year.