9mm Ball Mk1 and Mk2 differences


#1

I am trying to find out the difference between Australian 9mm Ball Mk1 and Mk2.
Even though Commonwealth SAA was supposed to be identical to that produced in the UK. It is not as simple as comparing these two loads as manufactured in Britain where the Velocity of the Mk1 is about 1200 fps and that of the Mk2 about 1300 fps.

Original documentation from Army Inspection Service, dated 1st March 1944, states that the Australian 9mm Ball Mk1, which was loaded with 6 grains of Ballistite B.16, had a mean corrected velocity of 1310 =/- 30 fps.
Does the Mk2 have a higher velocity, or just a different powder type? Or What?


#2

The documentation I have seen at Royal Armouries Leeds is a bit confusing (at least to me).
Ordnance proceedings 34147 of 1947 list Australian (!) Mk 1Z as 1319 fps (lot MF 79) and 1310 fps (lot MF 80). This is at the level usually associated with Mk 2Z.

On the other hand, Canadian and British Mark 2Z in a trial report from Woolwich 1957:
1311 fps (Canadian DA 55) and 1267 fps (UK RG 29.11.55) from L2A3 gun
1324 fps (Canadian DA 55) and 1264 fpd (UK RG 29.11.55) from Sten Mk 5

My own measurements from an MP5 clone show the Mk 2Z (RG postwar) on par with modern 9 mm ammunition, but not hotter, as is sometimes said. I did not see documentation clearly explaining velocity differences between Mk 1Z and 2Z.


#3

This keeps getting more confusing as time goes on. The following tends to disagree with the instructions issued by Army Inspection Service in 1944. In addition, in 1945 the cap was changed from brass to cap copper as used in the .303 production.

edit: The Mk2 reverted to brass caps when production commenced in 1964.

[quote]According to “Regulations for Army Ordnance Services V3 Pamphlet 11A 1/4/1949” the 9mm 1z and 2z are as described below.
Ball 1Z 4.8gr N.C. charge. Bullet weight 115gr. Cupronickel or Gilding metal envelope and lead/antimony core. No cannelure. Secured by being tight fit in case. MV 1250 fps. (note early manufacture gave inconsistent performance). Brass cap secured by ringing or stabbing.

Ball 2Z 6gr charge of American DB powder (SR4898). Bullet as per 1Z. MV 1300fps. Brass cap filled with “664” composition.
[/quote]

From this I can assume the Mk2 was solely differentiated by the use of SR4898 powder and 664 cap composition.

Cheers
John