View Full Version : 20mm - Dangerous??

05-21-2007, 10:07 PM
I was able to examine an artifact tonight and would like some words from the experten.

This is what I believe to be a 20mm aircraft shell. It was picked up on the beach near St. Andrews, Scotland in the early 1970's. It is 2 cm in diameter and 8.5 cm long. There is a seam near the pointy end, and some suggestion of circles on the base.

I have two questions:

1: What is it?

2: Is it dangerous?


05-21-2007, 10:13 PM
Originally posted by jolly_magpie:

2: Is it dangerous?

Only if you try to swallow it http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

Seriously though, it is a cool find. Looks to be a 20mm but from an aircraft? Maybe.


05-21-2007, 10:15 PM
Just going by dimensions....could be a MG151/20 (20x82). Could be something not fired from a plane as well.

As for dangerous...hard to say. I don't think they used radioactive substances for the bullet tips if its WWII. The danger could be if it were a HE shell...not sure how the explosive degrades over time. Could be a AP round in which case its just steel and probably quite safe.

Interesting find! I'm sure someone else with more knowledge can do much better than I can. Thanks for sharing!

05-21-2007, 10:19 PM
Yes, I also think it may be AAA. Hard to say, there were a lot of bullets whizzing around in those days.

I handled it with care and cautioned the owner not to subject it to sudden impacts. I'd like to get beneath the rust but didn't want to start the dremel tool without knowing what lay beneath in terms of explosive capacity.

05-21-2007, 10:24 PM
Some info:



This is the "granddad" of all 20 mm cannon cartridges, being used in the German Becker, developed during WW1. About 360 guns had been delivered by the end of the war, with about a third of them fitted to aircraft and the rest issued to troops for anti-aircraft and anti-tank purposes. As well as the solid AP shot shown, an HE shell with a very prominent plunger-type nose fuze may be found.

A very similar cartridge is often confused with the Becker; this is for the German Ehrhardt, which entered production by the end of WW1 but did not make it into service. It has a slightly wider case (see item 494-17).


After WW1 the development of the Becker was continued, first by SEMAG of Switzerland and, at the end of the 1920s, by Oerlikon. The cartridge case was slightly enlarged and used in Oerlikon's Type F, or FF, which saw service in various air forces during the 1930s. The gun was most famous for its adoption by the Japanese Navy air force under the designation 20mm Type 99-1. Among other planes, this equipped the initial marks of the Mitsubishi A6M "Zero" fighter.


The German Luftwaffe decided in the late 1930s to adopt a light cannon to equip its fighters and selected the Oerlikon FF, which they made under licence as the MG-FF. However, they made some changes to the gun and ammunition, including lengthening the cartridge case. During 1940 they introduced the "Minengeschoss" (mine shell), which was made by drawing the projectile body in the same way as a cartridge case rather than drilling a cavity for explosives. This enabled very thin projectile walls to be made, doubling their HE/I capacity while also reducing their weight. The recoil characteristics were different, causing the gun to be modified and subsequently given the designation "MG-FFM"


The Lufwaffe only adopted the MG-FF as an interim measure while a more effective gun was being developed. This emerged in late 1940 as the Mauser MG 151 in 15x96 calibre. However, the advantages of the high-capacity M-geschoss shell were soon realised, so the cartridge case was necked out and shortened to take the same shells as the MG-FFM. The gun designation was changed to MG 151/20, and this remained the Luftwaffe's standard aircraft cannon from 1941 to the end of WW2. It was also used by France (latterly as a helicopter gun) until at least the 1970s. It was unusual in being offered with two different priming systems: electric (for synchronised guns) and percussion. The yellow with green band colouring on the projectile shown (and that of the 20x80RB) indicate an HE shell with a self-destruct fuze, as typically used for home defence.


This cartridge was developed during WW2 for the Japanese Army air force's Ho-5 cannon, also known as the 20mm Type 2. The gun was based on a slightly enlarged Browning M2. As designed, it offered an impressive combination of high performance and light weight, but the lack of high-quality steels for gun-making meant that the ammunition had to be significantly downloaded to reduce the stress on the gun mechanism. Despite this, the Ho-5 was the Army's standard aircraft cannon at the end of WW2.


This cartridge was developed in the late 1930s for the Soviet ShVAK aircraft cannon. In fact, the gun was first produced in 12.7x107R calibre, using a rimmed case which was quite different from the later (and still current) 12.7x108. However, that saw very little use, the cartridge soon being necked out to 20 mm calibre.

The gun had a good rate of fire, but the performance of the cartridge was not impressive, as the light shells held little HE.As well as being extensively used in Soviet aircraft during WW2, the gun was also fitted to some light tanks. At the end of the war, the Berezin B-20 appeared, a lighter gun chambered for the same cartridge. The cartridge has survived to this day because it is used in sub-calibre training devices.


When SEMAG took over the development of the Becker, they also introduced a more powerful version using a longer-cased 20x100RB cartridge. Oerlikon continued its developed as the Type L (later the FFL). This saw very limited use, except for its adoption by the Japanese Navy air force as the Type 99-2, with a fractionally longer cartridge case. This supplemented the smaller Type 99-1, replacing it in service in later marks of the A6M Zero, and was the Navy's standard aircraft cannon at the end of WW2.


This cartridge was developed in the interwar years by Solothurn, a Swiss company closely associated with Rheinmetall (Germany being banned from developing certain armaments by the Treaty of Versailles). As it is the smaller of the two 20 mm rounds developed by Solothurn it is commonly known as the "Short Solothurn". It was developed in conjunction with the Lb 204 aircraft cannon, which saw little if any use, but saw service in various armies in the Solothurn S18-100 series anti-tank rifles. It is therefore generally found loaded with AP projectiles, of which there are various types. Rather bizarrely, one variant (the S18-350) was used as an aircraft gun by the Dutch air force, despite offering only semi-automatic fire. 20x105
This Rheinmetall-Borsig development was the successor to the 20x105B, the change apparently being made to improve the reliability of ammunition feeding. It was used in the MG 204 aircraft gun of the late 1930s, which saw only very limited service in some Luftwaffe seaplanes.


After Oerlikon took over the development of the SEMAG guns in the late 1920s, they developed an even larger version of the gun around this cartridge. It was known as the Oerlikon Type S (or FFS in its aircraft version) and is probably the mostly widely used 20mm cannon ever made. As an aircraft gun it saw only limited use with the French air force in the 1930s, but it was adopted by the RN and USN and became their standard light AA gun in WW2. It lasted in RN service certainly until the late 1980s if not later, and remains in use around the world to this day.


This cartridge was developed in France in the mid-1930s for use in the Hispano-Suiza HS 404 aircraft gun. It is similar to the 20x110RB described above, except that the rim is the same diameter as the body and the shoulder is sharper. The gun was adopted by the RAF as the 20mm Hispano, remaining in service until replaced by the 30mm Aden in the mid-1950s, and was also used by US aircraft in and after WW2. The last version of the USAF's gun, the M24, had electric rather than percussion priming. This gun and the postwar HS 804 have been widely used as aircraft and AA guns, and the ammunition remains in production. The cartridge was also used in the postwar Bofors m/45 and m/49 aircraft guns. The third photo shows a postwar Swiss API round.



This rivals the 20x105 as being one of the least-used cannon rounds. It was developed in Finland in the mid-1930s by Aimo Lahti for his L-34 "boat gun"; a light automatic cannon fitted to about a dozen patrol boats. Various experimental versions were developed, and belted cases may also be found.


This cartridge was developed in Denmark in the 1920s for the Madsen automatic cannon, offered in various mountings for aircraft, AA and anti-tank use, although only successful in the AA role. It was never the primary armament of any major army, but was widely used in WW2 and remained in service for decades afterwards. The ammunition for the gun was made in several countries, mostly notably in the UK by Kynoch, as was usually the case for Madsen ammunition as they had no ammunition production facilities of their own.


This Japanese Army cartridge was first used in the Type 97 anti-tank rifle introduced in the late 1930s, but during WW2 the mechanism of this semi-automatic gun was adapted to create an automatic aircraft cannon. This saw limited use in two versions; the Ho-1 for flexible mountings and the Ho-3 for fixed use. The guns were too slow-firing to be considered successful and were replaced by the Ho-5, which was lighter and had twice the rate of fire.


This was the second of the 20mm cannon cartridges developed by Solothurn in the 1930s, and is known as the "Long Solothurn" round. It proved far more successful than the 20x105B, being primarily used in the highly successful FlaK 30 and 38 AA guns which were extensively used by German forces in WW2 (and remained in service in some nations for decades after the war). It was also used in the KwK 30 and 38 light AFV guns, and in the Solothurn S18-1000 series anti-tank rifles.
As well as being used in these German and Swiss weapons, it was used in the Finnish Lahti L39 anti-tank rifle and L40 AA gun, and in the Italian Breda M35 and Scotti cannon. A very wide range of ammunition was developed for this gun, including M-geschoss shells and Pzgr 40 tungsten-cored AP.

20x139 FMK

This was developed in Switzerland in the late 1930s for the FMK aircraft gun (which saw limited use) and the Flab Kan 38 AA gun, which remained in use for some time after the war. This cartridge is very similar to the postwar 20x139 cartridge for the Hispano-Suiza Hs 820, but the rim is thinner and the cases of brass. The example shown here is a drill round.


This was the ammunition used for the Japanese Army's Type 98, their standard light AA gun from the late 1930s to the end of WW2. This powerful round was also credited with some anti-tank capability and so came with AP as well as HE projectiles. There was an earlier Type 94 AA gun which used even larger (20x158) ammunition, but this saw very little use before being replaced by the Type 98.


This was a Bofors development for their m/40 AA and anti-tank gun. It was in effect a scaled-down version of their famous 40 mm, but did not achieve anywhere near the same success and the cartridges are now uncommon. This case is fitted with a non-standard dummy projectile.

05-22-2007, 12:25 AM
I'll bookmark this thread.... excellent info Freelancer.

05-22-2007, 01:42 AM
looks like the 20mm hispano rounds i have on my shelf to me http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

05-22-2007, 01:52 AM
Just to be on the safe side (in case it is a high explosive round), I'd take it to a local military base and have them look at it. Not worth getting a hand blown off, or worse.

05-22-2007, 02:09 AM
Originally posted by jolly_magpie:
2: Is it dangerous?

Yes, and if you're not sure. YES
Any 'unexploded' shell, ect is dangerous until proven otherwise.

05-22-2007, 02:34 AM
2: Is it dangerous?
If it's MG151/20 - you can give it to children to play with it.
If it's a Hispano - RUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUN!!!!!! http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

05-22-2007, 03:19 AM
Originally posted by K_Freddie:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jolly_magpie:
2: Is it dangerous?

Yes, and if you're not sure. YES
Any 'unexploded' shell, ect is dangerous until proven otherwise.
http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif </div></BLOCKQUOTE>Was about to say the same. Put the shell in a large wooden box or something similar and put some rags or towels around it so that if it does explode it does so with minimum effect. And do let some expert take a look at it.

05-22-2007, 06:58 AM
In the '50 my grandma's cousin lost 3 fingers after he picked up one of those shell. (not sure it was a 20mm but my grandma remember it was bigger than a normal bullet)


05-22-2007, 07:00 AM
Originally posted by Brain32:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> 2: Is it dangerous?
If it's MG151/20 - you can give it to children to play with it.
If it's a Hispano - RUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUN!!!!!! http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif </div></BLOCKQUOTE>RotFL http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

05-22-2007, 07:02 AM
Originally posted by p1ngu666:
looks like the 20mm hispano rounds i have on my shelf to me http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif He he long time no see

I noticed that you aren't so frequent on the forum anymore p1ngu..... http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

05-22-2007, 07:10 AM
BTW jolly_magpie if you have more things like that we could fill some of this stuff:


http://forums.ubi.com/images/smilies/59.gif http://forums.ubi.com/images/smilies/35.gif

05-22-2007, 07:32 AM
Some guy wandering in the alps was killed by an explosive from WW1 in the 90's. I would be careful, if it is an HE shell it may still explode. Such things keep happening and if you are not tired of life you better bring it to the police.

05-22-2007, 10:30 AM
The dent near the tip might be from striking something. Also due to the seam about 1/2in from the tip I would have this checked out before doing any dremel work. Most types of bullet jackets are only open on one end, and are punched out using one piece (closed on the tip end) of brass/alloy. This was to help retain weight after impact. If the nose of this one has been pressed in to a jacket there could be a charge behind it.

05-22-2007, 12:57 PM

Your first pic shows no rifling in the band.
This indicates that the shell was not fired by a gun, could be a dumpage of ammo in the sea. The casing could have been lost due to corrosion in the salty sea.The dents are also due to corrosion
Now if its a WW2 round or just a postwar. hard to tell without id marks (stamps) or colors.

Get rid of it anyway, in a civil way, Dont Try to fiddle with it,.

In case it has Explosivs in it, Here is a piece of advice, dont touch it, Explosivs have the nasty habbits to become instable.

Best is it to blow the dam thing up by the military, they dont exam it either in this case.


btw Its not a German shell anyway. Only the AP comes near , but the shell you have is to long,

This is a 2cm FLAK , and its destroyed after it was found


this is a 40L70 AP round, it was recovered from the ground at a shootingrange, it has NO explosivs in it, it was sandblasted, and it misses it windcap. You can see the riffling in the brass band.

05-22-2007, 01:48 PM
Consider it as lethan until you know better.

Most HE-shells got a safety device that prevent the shell from detonation an acceleration fuse.

It has not been fired through a barrel because it got no marks from the rifling of the rear driving band as mentioned earlier.

It looks like a projectile or AP or training projectile. It looks as if got no tracer, and no mechanism for detonating the projectile.

I would guess that it comes from a damaged shoot or that someone has taken away the projectile from the cartridge to have it for decoration or use the powder for something else.

It can be everything from 10 to 50 years old.

05-22-2007, 03:17 PM
[QUOTE]Originally posted by jolly_magpie:
2.is it dangerous? hit it real hard with a rock,that should answer your question? http://forums.ubi.com/images/smilies/35.gif

05-22-2007, 03:24 PM
Hmmm... sobering thoughts indeed. I will inform the owner of the shell.

This reminds me of when I was scavenging around a crashed PBY Canso. Found some spent .303's and some LIVE rounds that had been rotting away in the bush for 50 years, we recovered them and gave them to a local gunsmith for proper disposal.