Trying to Identify Cartridge Case, 75x540


I took a chance on a cartridge case I found at a friends place (same guy I got the 155 projectile I asked about in another thread). It didn’t look familiar, so I grabbed it…the base was a bit rusty, so I couldn’t discern any headstamps…

Got it hom, and finally had a chance to measure it and see if there was a headstamp…completely unmarked, no markings what-so-ever on the base…so no help there.

Overall length is 504mm, case mouth is 75mm, the rimmed base is 90mm. No primer, there is a threaded hole for one…about 20mm wide with the threads being approx. 15mm wide. Case is steel…it is almost completely straight walled, no discernable taper, and just the hint of a very small bottle neck near the case mouth, very short…but it doesn’t jump out. I was thinking possibly a PaK 40 case, but I thought it was too short, which it is, but looks very much like one.

Any ideas? For some reason I found some pics of a Japanese Type 90 AA round, and it could be that, but seems a bit long for that…

Thanks for any help!

75mm Skysweeper ammo crate from Maine

The Ammo Data Tables on my website list the Type 88 Japanese as 75x497 with a 94mm rim. The PaK 40 had a 100mm rim.

The closest seems to be the US Skysweeper 1950s automatic AA gun, which used a 75x539 case with a 90mm rim.


You know, I may have been hit with a sudden bout of dyslexia…now thinking about (but I will double check when I get home) I think it might have been 540, not 504…I am almost 100% positive…

So it may very well be a skysweeper case…if so, how common or uncommon are these, and whats the chances of finding a projectile?



Don’t know much about the ammunition but here are a couple shots of what I think is the 75mm Skysweeper taken at Aberdeen Proving Grounds.



Thats it…pretty cool gun! There was a guy with one for sale a while back for 25k…wouldn’t mind having one for my back yard.

As an aside, its a shame how things are taken care of at Aberdeen…I know there is no money in the budget for any sort of real upkeep, but man, a lot of the pieces were in bad shape when I was there like 10 years ago, I’d hate to see some of them now. Irreplaceable pieces of history rotting away…they’d be better off giving them to collectors who would take care of them…


I was stationed at Aberdeen for a while back in the late 1980’s. The material outside was in poor shape then. The sad thing is that the place was crawling with soldiers that could have been put into working parties to help keep this historical equipment in better condition. The soldiers’ time was already paid for and paint is cheap…



The Sky Sweeper pictured isn’t in as bad a condition as allot of the pieces, though they are refurbishing some of them. I don’t know if they have an example of the round in the upstairs portion, but I’ll check this weekend. Moderator, I know this next is kind of off topic but it also kind of pertains form a collector standpoint. What is the shame was seeing one of a kind items, like the cannon for the ME262 in the weather over by the Ordnance School. From what I’ve heard, once the BRAAC is finalized, the Ordnance School is going down to Ft. Lee and they are going to move the Museum also. The amount of items going will be limited, though the contents of the Vault (Small Arms) are supposed to be a priority. Whatever they have the money for will be sent, otherwise. All the rest will either go to Anniston or ?? What is also a question will be the disposition of all of the Inert Ordnance items that are housed in a warehouse on base. I’ve been all over the Base getting pictures of all of the armor that I can find, for I don’t know when I will see it next.


If it helps, here’s a photo of a drill round for the Skysweeper. The long section of the scale is 30 cm.

Here are some measurements:

Head diameter: 90 mm
Case length: 559 mm
Exterior case diameter at shoulder: 78.7 mm
Exterior case diameter at projectile: 76.5 mm
Length from shoulder to case mouth: 71.2 mm

Note that my case length is 20 mm longer than what Tony Williams listed. This is a one-piece drill round, and I suspect that what appears to be the case neck includes what would be the driving band on a live projectile. If this assumption is correct, you’d deduct 20 mm for the driving bands to arrive at a case length of 539 mm, and a length of 51.2 mm from the shoulder to the case mouth.

I hope this helps!


That is a big help, I would say that is it…I did remeasure and it was 540 (or 539 considering I am using a tape measure!), and it sure looks like that…

Strange it has no headstamp, but I’m glad I took the chance on it…now to find a projectile!

I would also agree with you that your case would include the driving band length, since there doesn’t appear to be a driving band on the drill round, and really why would one bother when manufacturing a drill round…


pzjgr, this is the round:

  1. Cartridge, 75 Millimeter: HE, M334 (T50E2), Steel Case, MV 2,800, w/Suppl Chg, w/o Fuze
    a. General. This cartridge is intended principally for fragmentation, blast, or mining effect against both air and terrestrial targets. It consists of a percussion primer M58 and 3.62 pounds of propellant M6 in cartridge case (brass) M35 or (steel) M35B1. The cartridge case is crimped rigidly to the projectile. A 1/2 ounce strip of tin-lead foil, which acts as a de- coppering agent to prevent the formation of copper deposits in the bore of the gun, is included in the cartridge case on top of the propelling charge. The projectile is a conventionally designed deep-cavity nose-fuzed projectile with a hemispherical base. The projectile contains a high-explosive bursting charge of 1.42 pounds TNT and a supplementary bursting charge of 0.33 pound TNT contained in an aluminum sheet liner. The nomenclature of the item will indicate the appropriate muzzle velocity. The cartridge is shipped unfuzed with a closing plug assembled in the nose of the projectile. This cartridge case is made of brass.
    b. Data.
    Weight of cartridge (steel) (w/plug) …20.06 lb
    Length of cartridge (w/plug) …30.45 in.
    Weight of projectile (w/plug) …8.79 lb
    Weight of projectile (w/o plug) … 8.40 lb
    Length of projectile (w/plug) …11.96 in.
    Length of cartridge case …21.30 in.
    Width of rotating band … 0.87 in.
    Type of base …hemispherical
    Radius of ogive … 6.07 cal.
    Muzzle velocity … 2,800 fpS
    Maximum horizontal range …,…,…,.,…14.415 yd
    Maximum vertical range … 10,000 yd

  2. Cartridge, 75 Millimeter HE, Comp B, M334 (T50E2), Steel Case, MV 2,800, w/ Suppl Chg, w/o Fuze
    This cartridge is similar to the cartridge in paragraph 61, except that the projectile is loaded with a high-explosive bursting charge of 1.42 pounds of composition B.

The publication I got these from was the TM 9-1300-203, Ammunition for Anti-Aircraft, Tank, Anti-Tank, and Field Artillery Weapons dated August 1960

Please take note. These and the 90mm HE T91 were some of the only rounds fielded by the US in larger caliber weapons that had a hemispherical (rounded) base. They pretty much took the idea off of the Luftwaffe 20mm and 30mm mine shells so they would have a greater burst radius and kill capability.