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20x110RB hstp/markings

F

falcon5nz

Well-Known Member
Anyone feel like translating?
Hstp= (12/4/8) 55/RG/oez

Markings stamped into wall just above rebated portion (5mm letters)
SWN/262/56/HEI/TNT/N12Z

I'm guessing the HEI is High Ex. Incendiary and the TNT is the filling of the projectile.
 
20mm Oerlikon markings

Hi falcon5nz,
The stampings translate as follows:
55 = 1955 (year when case made)
RG = Radway Green (Ordnance Factory in Cheshire, where case made)
Oe = Oerlikon (the gun it was for)
SWN = Swynerton (filling factory)
262 = Lot number
56 = 1956 (Year filled)
HEI = High Explosive Incendiary
TNT = Explosive compound in shell
N12Z = not sure on this, one of the experts will have to tell us!
 
I'm positive it's N12Z. Could it refer to NZ load or something?
Also any ideas on the "Z" after the "oe"?
 
Z

The "Z" after the "Oe" simply means that the round is loaded with nitro cellulose propellant, rather than cordite.

This code applies to all British SAA, e.g. 303 Mark VIIz, 9mm Mark 2z etc.

Regards
TonyE
 
Z

That's not the way British nomenclature works. Why would it be assumed to be nitro? Plenty of large calibre SAA was cordite loaded.

Regards
tonyE
 
I know, I know. Never assume anything. I suppose the date made me think it would automatically be nitro. (When did the "Z" stop being used? Any ideas on N12Z?

Nick
 
"Z"

The "Z" dropped out of use for newly introduced ammunition in 1954 when the UK adopted the NATO system of nomenclature and introduced the L1A1 style of numbering.

For existing stores the use of "Z" was continued, and I think the last I have is .303 made by Radway Green in 1973 headstamped "RG 73 7Z" (made for cadet forces).

Regards
TonyE
 
I have still had no luck with the N12Z bit.
It is definitely N12Z not MK 2Z(it is a definite 1 not l)
Could it be something to do with New Zealand e.g. When New Zealand purchased ships or equipment off the UK the ammo was part of the contract?
gravelbelly on the IAA forum suggested the fuse. Thoughts?
 
Hello Falcon, have just found this thread & I think you'll find that the 'N' with respect to your Oerlikon round refers to naval use. Quite a lot of British naval cartridges have the figure N included with their mark numbers.

Regards,
Ian.
 
Just to confirm with Nicks markings...the one I have is the same, SWN/259/56/HEI/TNT/N12Z.
not too sure about the N denoting Naval use...who else was using 20x110RB at this time anyway?

Tony

P1150007.jpg


Well I eat my words about the N !........according to Labbett and Browns T.A.G series 2 pamphlet 12 'from about 1946 the British service Oerlikon ammunition had details of projectile type ect ect blah blah' so the N does indeed mean for naval service,the 12 is for Mk12 and of course the Z is for nitrocellulose

Tony
 
Last edited:
sorry hangarman,I must have been editing my post while you were typing....'tis defo Mk12,Labbett and Browns pamphlet shows an example of this code with a Mk13 round

Tony
 
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