Mauser-IWK 5.56mm 77gr "heavy ball"


By chance can anyone please post a photo of this cartridge? Sectioned preferred, if possible.

If a photo is not available, a sectional view, line drawing would also be okay.


I have quite a few of these interesting rounds with IWK, NWM and no headstamp in ball, armour piercing and tracer. These were all produced for the US Stoner 63 weapon system in about 1968. Sorry but I don’t do ‘sectioned’!

Here’s a [b]5.56mm Cartridge-77gn bullet-twist 1:200 1:8"[b]



Some more from the Stoner 63 series;


Thanks very much, Jim. This is the first time I’ve seen a photo with Tracer and AP versions of the 77gr Ball load. Do you know the Tracer and AP projectile weights?


Here all cartridges I have in this series:

Fifth and sixth are proof cartridges

Now, projectiles:

77 grain Stoner 63 (from first cartridge above)
55 grain M193 (AD 06)
68 grain sniper (F C 6 6)
62 grain SS109/M855 (RG 02)
77 grain MK262 (L C 0 2)

Jim, why do you say fifth and sixth cartridges are from Stoner 63 series?




I’ve used a combination of three references when trying to identify these cartridges;
David Hughes ‘The History & Development of the M16 rifle and it’s Cartridge’,
Gordon Conway’s 'Conjays Collectors Catalogue no.11,
Ron Fuchs ‘5.56mm Book’

In hindsight I don’t think number 5 is actually from the Stoner series. As far as I can make out it was made by NWM to US specifications for a 1:12" twist barrels. According to Conjays it has a 63gn bullet (tungsten core?) and is designated ‘5.56mm Patroon Pantser’ which would suggest it was not connected to Stoner.

According to Hughes’ book number 6 is an unmarked 68gn Armour Piercing made by IWK/NWM (page 111) and he shows a colour picture which certainly looks to be the same cartridge (colour plate 2, item Z, if you have the book). He doesn’t specifically say that this particular cartridge was for Stoner but he does describe it in the same paragraph that he is talking about Stoner AP rounds. He doesn’t say that it was made for any other purpose so I don’t know!



For stanc:

(on my scales)

Tracer Red tip H/S NWM 5.56 67 Green primer annulus weighs 59 grains

AP Black tip M193 style bullet no H/S weighs 61 grains

AP Black tip Pointed bullet No H/S weighs 69 grains


And what do I have in the center.



I want to show some 5,56x45 IWK boxes

tracer cartridges
headstamp: NWM 5.56 67

and two unopened boxes

High Pressure test cartridges

metal blank cartridges


And a unopend box from the NWM with 77 grains bullet



Unless I’m missing something your cartridge is just a 55gn M193 Ball for Dutch military use.


Unless I’m missing something your cartridge is just a 55gn M193 Ball for Dutch military use.


In 1973/74 I was in the Dutch army. As far I know not one unit had a .223 these day’s.
The standard rifle was a FAL Kal. 7,62
These NWM .223 rounds were made in 1967.!!!



These cartridges were used in the Stoner made by NWM…under licensee
according to this sales program from 1967



NWM sales Program from august 1971


And although NWM produced the Stoner rifle under license, the Dutch army never accepted it.

Other projects were the AR10 and the CETME rifle and Henk Visser’s personal playthings in the shape of some pistol designs.

NWM also delivered the barrel steel for the post war Mauser Parabellum pistols in .30 luger and 9x19 para.



For those that do not read Spanish, I provide this literal translation into English.

“Shown is the flashhider of the CETME Rifle, which is of a design that also serves as a Grenade Launcher to propel
all classes of rifle grenades, such as anti-tank, fragmentation, smoke and signal; with which it is possible for each soldier with the CETME Rifle to combat (engage) different targets at great distances, with the most modern grenades of this type. The special NWM propulsion (grenade-launching) cartridges for these grenades have an exterior form almost equal to the normal (Ball) cartridge, with which it is possible to load directly into the normal magazine, when it is so desired.”

Hope this helps.

John Moss


This experimental cartridge is made out a 9x19 aluminium NWM case

headstamp NWM-68-4 9x19


Harrie - it is hard to believe that they could make a 5.56 x 45 case with proper case wall thickness at the
various points of the c ase out of a 9mm case. I would not think there would be enough material in the whole case to do this,
especially with aluminum? Are you sure they didn’t just make the case originally as a 5.56 x 45 and
simply use a 9mm headstamp bunter for convenience and economy for in-house-identification?

If they really did manage to stretch out a 9mm case to 5.56 x 45, do you know what process they
used to do it?

John Moss


The rifle grenade in the photo seems identical to the spanish Instalaza grenade, although surely it’s the other way around.
Does anybody know who was the manufacturer of the rifle grenade depicted in the photo?

The NWM grenade blank cartridge is the one with the star sealed with tin solder. The spanish replica to this round (same tin soldering) was made experimentally at Toledo in 1965.