Preserving steel cartridges


Is there a way of preserving this type of steel cartridge as the rust on the case sides appears to be increasing…


German Steel cases were made to be used within a year of manufacture.
The reason for the deterioration is complex; The cases were made by parkerising steel ( Bonderising process, with phosphoic acid), drawing the cases by a rapid, two draw process (not four draw, as in brass) and then the outside was varnished(lacquered) with a protective and lubricating lacquer after loading. The inside surface of the case was left at its parkerised state.

Also, in the case drawing and forming process, the stresses remaining in the neck and especially shoulder area of the case were not “normalised” (annealed out).
With Age, the wartime Powder deteriorated…by 1960, 1940s Powder was beginning to break down into Water and Nitric acid and carbon compounds.
This led to the corrosion of the case from the inside, with subsequent “pin-holing” rust appearing under the lacquer. ( Stress Induced Corrosion) It also led to increased deterioration at the shoulder of the case, and catastrophic case separations in MGs ( as in MG shooting in the USA, where it is legit.)

Case problems with steel-cased German WW II ammo was first noted in the Biafran Civil War(Nigeria, 1960) and the US MG community (Mid 60s, early 70s).
Even later (East German) manufactured Steel cased 7,9x57 and 7,9x33 ammo is now deteriorating in the same way ( my dates are 1960s).

Solution: Get rid of the Powder, it is probably all gone bad, anyway.
Pull the projectile (Inertia Puller, but first “re-seat” the Bullet slightly to break the seal between case neck and jacket…and consider that the corrosion inside may be such that the bullet jacket is rust-seized to the case neck, and you may crack the entire case open.

Once the bullet is out, remove all the powder using a BRASS or COPPER wire pick, making sure you get all the powder out (Steel cases were usually loaded with a Flake Powder although some lots had Tubular Powder in them).

Next, get some Vinegar, warm it, and fill the case up. This will Kill the primer (they are usually dead, anyway, but the composition can also corrode a steel case). After 12-24 hours, flush out the vinegar and any rust with hot water. Allow the cases to Air dry, upside down.

There should be no rust left in the case now. One can either spray some RP7 or other protective spray inside, or alternately, get some “Rust Plus” (Phosphoric Acid rust converter) and lightly coat the inside of the case.

For the rust on the outside, there is nothing to be done, unless you want to remove the varnish, clean the rust and revarnish ( a bit of too much “restauration”).

Once all the work is done, re-assemble, using dry clean sand (not sea sand) or sodium carbonate as a filler to the same weight as the Powder ( see Kent or “Die 7,9mm Patrone” for charge weight details). And label as “restored” or “de-activated”.

It is a sad fact that all cartridges(brass, or steel) will eventually deteriorate due to Powder breakdown, some quite quickly (15-20 years) others ( esp. Cordite loads) in over 100 years; but deteriorate they will, by the very chemical nature of both Nitrocellulose and Nitroglycerin.

At a certain stage in the life of every collectible smokeless cartridge, the decision will have to be made to remove the deteriorating Powder charge in order to conserve the Outer case.

regards, Doc AV
AV Ballistics
Brisbane (Qld)

  • I’ve fired 9X19 and 7.92X57 rounds with steel cases [WW2 German manufacture and early 1950s Czech manufacture] with no problem with pistols or bolt action rifles. Today in USA the Romanian made 7.92X56 rounds with green lacquered steel cases [manufactured between 1972-78] are well appreciated and I heard no complains about this type of ammo. — Terry, to clean the little rust formed on the side of those WW2 made rounds with steel cases you may want to use a cloth with a few drops of WD-40 or gun oil. It may take time to see good results, you definitely need patience. Be careful where you keep that ammo with steel cases to avoid more rust in the future. Liviu 04/11/07


I wouldn’t shoot a German (or occupied country) 7.9 x 57 round with steel case under any circumstances. Every time I open a drawer of my 7.9 collection I find another round that was mint yesterday and badly rusted today. The rust is not forming from outside influences - they are rusting from within, and wiping them off with any kind of oil is a temporary solution at best, and a waste of time at worst. One round that was mint, and then “bloomed” with some rust from the inside was so badly rusted inside that when I tried to pull the bullet, the entire top half of the case came off with the bullet. Had I fired that round, and had the cartridge gone off (which I admit is doubtful), the results would have been catastrophic. I think I mentioned before that some time ago, I saw 7.9 x 57 steel cases in the garbage can at our range, along with a couple of empty German 15 round boxes. Every case was split from case mouth down to just above the base of the case. None of them were especially rusty on the outside. The capper was that the boxes indicated that they were SmkH (it is the only SmkH box in my collection), so the gun had shot up 45 rounds (the number of cases I pulled out) of 25 dollar specimens, probably for poor results. The gas that must have escaped out of the huge crack in the side of the case probably didn’t do the chamber of his rifle much good, etiher. While I don’t shoot it, I have not seen 1/10th of the problems with steel case 9mm. May have something to do with powder types. I simply don’t know. I don’t know a single collector who has a lot of steel cased WWII-vintage German 7.9 that doesn’t have this internal rusting problem, ruining specimens one by one. I agree with Doc AV - it will eventually ahppen to all of them. In the interim, regardless of their past experience, I would urge people not to shoot this type of ammo. The Romanian steel-cased ammo is much newer, and has not seemed to have any problems yet. Whether this internal rusting will happen with it in the future is up to time, or expert chemists and metallurgists , to tell us. German steel-case technology during the war was not up to that of the US. I am still shooting Evansville Chrysler steel-cased .45 ammo from WWII without problem, although I will no longer do that simply because I don’t shoot enough .45 anymore to worry about cost.

  • @ John: I don’t understand something: If the 7.92X57 ammo with steel cases of German manufacture from WW2 is so bad [and perhaps unsafe] to be fired, why this type of ammo was still recently sold as “surplus ammo”??? A friend of mine from Wisconsin got it last year and fired many rounds with no problems. Liviu 04/11/07


Liviu - I am not sure quality has any relationship to items sold. They are sold because people buy them. Period! Not all German steel rounds are bad - YET! Some are still very shootable.

I gave an opinion based on 38 years in the firearms trade, 45 years of collecting ammo, 25 years of collecting the 7.9 x 57mm Mauser round with an emphasis on German rounds, and 55 years as an active shooter (since I was 12, when I started shooting competition gallery smallbore). My remarks are simply my opinion. Everyone is free to think and do what they want, of course.

I have been criticised for some of my opinions on guns by people who have owned one of a type and think it is swell, when I might have sold, over the years, 300 or 400 of the same type and seen lots of problems come back to us for warranty repairs. Wartime P-38s are a good example. I have had lots of them throw off the spring steel top cover, lots of broken firing pins from dry-snapping (customer fault, of course, but…), even blown extractors. Repairs on Colt/Browning .45s, 38 Supers and 9mm were almost non-existent, other than a period when Colt went the way of Winchester and started changing things like the bushing, the grip-screw staking, and quality, and then we hads probem with broken fingers on the bushings, grip-screw escutcheons coming out with the screw when people tried to change grips, and jamming due to their redesigned, crappy magazines. However, none of that had to do with original design.

I have seen, over 25 years, the amount of steel cased German ammo in my own collection, and others, rotting through from the inside and I will repeat - I would not shoot one round of that stuff, at this stage, period! Unlike Superman, I don’t have X-ray vixsion to let me look into the case and see what’s happening before I shoot it. If one wants to shoot it, go ahead. I would advise shaking the case first, at least, to see if you can hear or feel the powder moving. If you can, that’s at least one hopeful sign that it is not all decaying and full of rust. The last round I took apart for rusting, by the way, had about 1/8 of an inch of the base of the bullet, almost the whole boat-tail, rusted away. Wonderful match-grade ammo!


Thanks all, as I only have a couple of dozen 9mm and 7.92 steel cased rounds with to me significant headstamps, I will take Doc AV’s advice
and attempt to remove the powder.
I am woried about disturbing some of the 9mm rounds that have a blackened projectile , I think cintered iron, the steel case ones show rust to the side of the cases but pulling and reseating the projectile, will possibly spoil the overall appearance , WHAT ABOUT DRILLING THESE ??



The inherent danger with drilling steel cased ammo is the possibility, however faint, of a spark igniting the powder to the detriment of the immediate environment (including body parts). I have ways of doing this which are, in my opinion, safe although I’m not going to discuss them in detail.

I would, however, note that a lack of oxygen in the vicinity of the cut, sharp tooling and patience are all good things to have if one were to attempt drilling the case. Loose powder can be removed by tapping, caked powder requires persuasion with non-ferrous substances (brazing rod is useful) and there are many chemicals which will dissolve and flush powder residues. Once the interior is clean, a good oil can coat and protect it.


  • @ Terry: DO NOT DRILL ANY LIVE CARTRIDGE HAVING A STEEL CASE!!! A spark from the drill may ignite the propellant from inside. If I were you I would do just NOTHING! — @ John: Yes, people buy those 7.92X57 German WW2 made rounds with steel cases to fire them at the range. Most of the people fire the ammo, only few collect it. It’s up to each person to inspect visually and to judge the quality of the ammo which is going to be fired at the range. From my experience I’ve never had a bad experience firing a 9X19 or a 7.92X57 old round with steel case but this doesn’t mean it cannot happen to another person. It’s a risk we should take in consideration. Liviu 04/11/07


One can drill steel cased ammo UNDER WATER, and use only a Hand drill(Never a high speed electric drill); Even with brass cases I always Hand drill them, using either a Jewellers Hand chuck (like a bow drill, but using a small sliding piece on a spirally grooved stem), or a small geared carpenter’s drill ( I have a 2 speed German one I bought some 40 years ago, for about $2.00, and except for a new “breast” piece, it is still going strong.

Use a small diameter drill ( 1/16th ) first, and then open up. The water won’t affect the case (it needs a clean anyway,) and No sparks will result.
For sparks to be generated, enough energy and heat have to be imparted by the drill to the metal to throw off a spark(actually a small shard of intensely hot metal)…one simply does not get this with hand drill speeds, or for that matter, under water.

Regards, Doc AV
AV Ballistics.


Thanks Doc, I was contemplating the same thing when Econoclast suggested a lack of oxygen, vice grips with padding and immerse the lot, after a gentle center punch mark, and yes I have a small geared hand drill.

I accidentally ignited the powder [black powder] in a brass center fire case case many years ago.
Not by drilling but simply scratching an old round that had holes eaten right through the sides, the projectile went a couple of feet one way but the case flew into a door about 8 feet away with a solid whack but no damage.
I was holding the round in my hand and scratching away verdigris with a needle.
I have been thankful that I was not holding the round with the case pointed towards me, as I think the powder burning in the case gave it a rocket effect
where as the projectile fell almost harmlessly to the floor.
It was the first W.R.A.Co. headstamp I had seen, and wanted to make it look good for my collection of possibly 60 or 70 rounds at the time, a long time ago.
Needless to say I have not scratched old rounds where the black spots look like they go right through the case since.