120mm Tank Gun Ammunition Dimensions

Hello All,
I have been searching all over for the case dimensions of the 120mm tank gun ammunition used in the M1A1 Abrams and I just can’t find it.I have a co-worker who was a Abrams “driver” and he didn’t know either.
Can someone please post the case dimensions (rim, base shoulder and neck diameter as well as the case length)
It would be much appreciated.

Remember, the 120mm gun in the M1A1 tank does not use a conventional metallic cartridge case, but has a metal base piece (sort of like the bottom 3" or so of a regular case, and the rest of the case is made of combustible materials which consumed when the gun is fired.

TM 43-0001-28 provides drawings of many different types of 120mm cartridges with an overall length dimension. That could be the basis for taking off dimensions at the various points desired. Some of the drawings are better than others, so check several out to find which works best for you and can be manipulated by your photo editing software.

Here is a link with download options in several formats. The .pdf format is searchable, and after going down about 10 pages of changes and list of effective pages you get to the table of contents which lists all the different types of ammunition from 35mm to 8 inch including gun, howitzer, mortar, recoilless rifle and grenade launcher types with each “M” designation and best of all a link to take you directly to that page.

There are many different editions of this manual, basically listing everything which is current as of the date of publication, so you may want to check older editions for obsolete items, or newer editions for items introduced later.

I assume that this is for the purpose of making a replica of some sort, and that would be close enough for most people.

These should help

I am the guy that made the one out of wood that was referenced in Spaceinvader’s post.

Let me know, if I can help.

I must admit. I have not been around much since the new format change. I know - shame on me. I will try and do better.

I might need some help in the future. Would love to get a nice 120mm APFSDS projectile, and have a wood lathe. Always planned on trying to make a casing.

Wood lathes are easier to find than projectiles - sometimes.

Managed to get a nice simple one of my local classifieds for 400$. Barely used and good condition, works like a charm.

Despite my great interest in APFSDS items, I am in Canada so it’s hard to find, most of it comes from the US. Hopefully will be getting a nice cone-stabilized penetrator soon!

Thank you all for your information and assistance.
I never thought of turning a case from wood to make my own dummy.
I have a ShopSmith with all the attachments so It would be fun.
All the best,

Case measurements actually do depend on the exact projectile a case is to be used with.
The case neck (and sowith length) is varying quite a lot with the different proj types + the case neck design as such is varying.

Just remember, like EOD just mentioned, there are many 120mm rounds fired from the M1A1 and each utilize a specialized “Case Addaptor” depending on what projectile is fitted to the case body so each round will have a slightly different neck profile shape.


As far as I remember -no much specific documentation is available- that round is identified as 120x570 mm, to include the metallic bottom part (approx 3 inches, like a howitzer case) and the combustible upper part of the case.

As APFSDS says, the exact lengh and profile of the case neck depends on the fitted projectile.

For a generic profile you may want to try google “120mm tank round” and go for the pictures and -few- schematics with different projectiles.

All the best, E.

Attaching a photo from my 120mm IAAA Paper that shows the basic construction components that details one case adaptor profile.