MG 151/20 "M" and AP "Gesteuert". Does anyone have Info

Ok I’ll try to hurry so does not time out. Who has infor on the German 2cm MG151/20 “M” round with word “gesteuert” ink stamped inbetween the two large “M”’. I know what the gord means (the attached TM of definitions) also have the CIOSC detailed interrogtion report from Mauser Oberndorf detailing the history of all electric primers and for whic each was developed. And I have the translated "Handbook of German Aircraft Ammunition, with color plates 19, 1956. This document on page 4 identifies for MG151 and MG 151/20 “synchronised” rounds will be used, and the special “sychronised rounds will not be requisitioned for any other weapon that does not fire through the propeller circle.” Mr. Tony Williams also told me he believe this was a marking to ensure these round were positively identified. I agree. I only know of 4 other round in collections with this marking. So my questions are:

Why is there no documentation about this rounds marking?
Why is such a specil round, made in quantity, not addressed in current German aircraft ammunition books. It certainly is not a “common” round.
Has anyone else got some of these? Have defenitive documentation showing the marking?

Can anyone help out?

Your’s must be likely a late war edq or tko production. These came in quantities from the DWM ponds in Lübeck Schlutup.

The reason whay they were marked as such is still a bit mysterious since the so called “unified cartridge” was approved for synchronized guns already.
Besides on HE-“M” projectiles I have seen this marking also on AP-I, HE-T, INC-T and TP-“M” projectiles, all from the same location and late war.

A possible theory (well - only mine) is that late in war lots of ammo was loaded from any components on hand for triple MG151/20 AA mounts, these had to fulfill much lower quality requirements and also needed no synchronization. So probably the little synchronized ammo produced for the few aircraft in air in those days just received a separate marking not to confuse it with the low quality AA ammo.

EOD: I believe the principal late war user of synchronized MG151/20 armament would have been the Focke Wulf FW190F series ground attack planes. These each carried two of the synchronized guns. Jack

Jack that’s correct. The FW 190 carried two in the wing roots.
EOD … my projectile is the only German 20mm (I have quite a few) that does not have a single stamp anywhere on the projectile body, and yes the date marking in ink is Iko 33/45. Also though 45; the driving band is copper. It is just strange to me that no one has written about this round.

1SFG, the “M” type HE shells usually have no stencilled markings, just color stamps. So this is in accordance to the book.

The copper driving bands on “M” projectiles are usual. I assume they were used till 1945 since the iron ones would have stressed the thin walled projectile body too much during the engraving process of the barrel’s rifling.

EOD: You know I never noticed that. That’s why I’m asking all the questions. Still do you have or have you seen a document that shows these gesteuert markings? And I’ve seen the sand color on FFM’s, but still not in a German color code document.//

I have seen no document on the “gesteuert” so far. I assume it happened too late in the war to find an entry into related documents. As said all ammo was qualified for synchronized guns but this one got marked since in late war ammo was made for the aircraft guns in ground use in the AA role which was of lower quality.

Late in war the paint used on ammunition was not always in accordance to “RAL” standards. I have seen yellow shells which were like lemon yellow down to almost brown ones. Quite some of the German paint was prone to aging and chemical reactions and faded or turned into entirely other colors like the 20mm navy AP-HE-T-SD which was blue initially but today is partially bright green and has some sort of blue green camauflage pattern.
Short, your “M” projectile here is well within the color range for German ammo of that time.

EOD … thanks again… Just went ito another box and found a great document I had forgotten I had “Defense Documentation Center” CIOSC Document Item Number 2, File XXXIII-20, Vistit to DEUTCH WAFFEN UND MUNITIONS FABRIKEN AG SCHULP NEAR LUBECK. About 150 pgs w/diagrams of various projectiles covers manufacture of 7.9 to 30mm and the 7.92X57 Training SD. It address the manufacturing there of the “M” rounds and the machining and development. I’ll have it scanned for me this week.
I still think a LOT of collectors and authorities on German Ammunition have missed the boat on this round. Maybe not… but sure seems worth someone over the years would have realized this round was different for a real good reason, and a lot of engineering went into it. As always THANKS.

1SFG, I never heard of this report, sounds very interesting. Any chance you can share it with us?

[quote=“EOD”]I have seen no document on the “gesteuert” so far. I assume it happened too late in the war to find an entry into related documents. As said all ammo was qualified for synchronized guns but this one got marked since in late war ammo was made for the aircraft guns in ground use in the AA role which was of lower quality.
EOD, I think you mean all electric-primed 20x82 ammo was qualified for synchronised guns. MG 151/20 guns firing this ammo (sometimes designated by the suffix EL) were only used in the Fw-190 series AFAIK, as already mentioned. I believe that all other MG 151/20 installations were non-synchronised and used guns firing percussion-primed versions of the ammo. The two ammo types were of course not interchangeable.

I gather that the risk of loading the wrong type of ammo was avoided as far as possible by keeping the Fw 190 planes separate from the others. One interesting and technically successful installation of the MG 151/20 was made in a Messerchmitt Bf 190G; it was mounted in a belly pod and synchronised to fire through the prop. The problem was that this required the electric-primed variant, and as the standard engine-mounted MG 151/20 was percussion-primed this could have caused a mix-up. The installation was therefore never adopted.

I was previously unaware of the “gesteuert” marking, presumably the arrangements for keeping the plane types separate broke down later in the war so more definite iD was needed. Otherwise, the only way to tell percussion and electric-primed ammo apart is to look at the primers (the electric ones having the characteristic inner ring).

On the more general issue of markings on 20mm Minengeschoss ammo, it is not uncommon to see projectiles with a large “M” stamped on them. “MX” can also be found on the (rare) rounds of this type, and sometimes other letters are stamped on too. Lippert’s hand-coloured drawings show this.

Tony, you are right, I did not limit it to the electric ignition as I should have.

I just do not have the date on hand when all the electric primed ammunition was “standardized” to status “fit for synchronized guns” or if it was already given by the presence of an electric primer from the very beginning.

Note that there were also other markings like “TP” or “Trop” (Tropen = tropics) for ammunition to be used in higher temperature ranges. The “EL” was used inconsistently for some reason.

The “MX” was not only used on the “long-M” but also on AP and HE projectiles when intended to be fired together with “MX” projectiles. The few I know of having been made eventually got destroyed in a train (or maybe two trains) to France where the weapons and ammo were supposed to be tested in combat.

I believe that all electric-primed ammo would have been qualified for synchronised guns from the start, because that’s why the electric-primed gun was introduced - and I’m unaware of any cases of electric-primed guns being fitted in anything other than synchronised installations.

I should perhaps explain, for the benefit of those who are unaware of it, that synchronising guns to fire through the propeller disc without hitting any blades was not a simple matter and a lot of different systems were developed from WW1 to WW2. Some systems were mechanical, some hydrosonic, some electrical. Germany settled on electrical systems before WW2, but in two different forms. For the 7.92mm MG 17, the electrical system sent a signal to a solenoid which released the firing pin which struck a standard percussion primer. However, the more advanced system developed for the 13mm MG 131 and the MG 151/20 had a more accurate system which sent an electric pulse which directly fired the primer. This enabled the guns to fire with maximum efficiency and meant that the loss in rate of fire was only about 10%, compared with around 25% (and as much as 40-50%) with other systems. Only Germany used electric priming for this purpose.

The 30mm MK 103 (30x184B ammo) adopted electric priming for synchronisation purposes also (the earlier MG/MK 101 used the same ammo with percussion priming) but this didn’t work in practice, apparently because the huge powder volume led to variable burning times which meant that the shot could not be precisely timed - and you don’t want a 30mm shell hitting your propeller!

Incidentally, electric priming for the 30mm MK108 (30x90RB) was adopted for a different purpose - probably simplicity - as the gun’s mechanism meant that it couldn’t be synchronised.

Thanks you for all your Info… It is beginning to become a real file of data. Surprised that more folks have not added what they may know about this round.

As for the CIOSC Shultup report … I’m having it scaned this week along with some others. BUT getting it into “filedeposit” is for me another story! hahaha I’ll let you know. I can always email cy’s once it is in Adobe.

In this same report there is two pages … one a diagram the other information on the German 9mm rocket cartridge that was in a couple journals. Not much, and may already be in the articles, but this is an official intelligence report on the item at Schultup. //

Hi 1SFG,

even if this post is quite old I can support you with some further Information on MG151/20 ammunition (also MG 151/15).
As I am from Germany (so I use metric Units only ;-)) I have available facsimile drawings of this ammuntion (over all drawings, projectiles and cartridges) out of the German “Waffen Revue” (I have all issues available).
These drawings are from the original factory drawings.
So if you are interested I can scan specific ones for you - please ask.
I cross read the different articles and found no indication on the “gesteuert” issue but differing “M” (which means Mine-Projectile).
I found 3 different ones:

  1. 2cm-M-Geschoßpatrone 151 ohne Zerleger (Air to Ground use, no self-destruction), Fuse: AZ1502, Weight complete: 183g, Projectile: 92g
  2. 2cm-M-Geschoßpatrone 151 mit Zerleger (Air to Air use, self -destruction after either 900 to 1200m ZZ1506 or 1400m ZZ1506), Fuse: ZZ1505 or ZZ1506,Weight complete 183g, Projectile: 92g
  3. 2cm-Minengeschoß “MX” Marking (yellow Body, green ring on top, fuse aluminium, self-destruction, Fuse: 1509), no further Information but weight 104g.
    “Geschoßpatrone” means the complete round and “Minengeschoß” is just the projectile itself.

General Color marking:
yellow projectile body: He and He-Incendiary
black projectile body: AP(always with explosive inside)
blue projectile body: Incendiary
Grey projectile body: blind
bright red ring on top of projectile body: Tracer
dark red ring on top of projectile body: gliming Tracer (not sure if glimming is the correct Translation, this means a Tracer which much less bright)
green ring on top of projectile body: Projectiles with self-destruction
yellow ring on top of projectile body: Projectiles with extended explosive i.e. AP+
blue ring on top of projectile body: Projectiles with extended incendiary

Letters on the outside Diameter of the projectiles:
“M”: Mine
"Ph": Phosphor (mostly used in AP)
“E”: Elektron (an easy igniting metal for AP-Incendiary)
Regarding the primers it seams to me that both exist for most of the ammunition: electric (P2 primer) and Standard (K-primer)



dark red ring on top of projectile body: gliming Tracer (not sure if glimming is the correct Translation, this means a Tracer which much less bright)[/quote]

Thanks for all the info. The English term you are looking for is “dim tracer”.