A look at 3 20mm HEI rounds,and their impact in the game(no pun intended)

[Tony Williams]

 

Originally posted by brady:
 Mr. Williams said:

AGW - My source is a restricted US Military Intelligence Division report on Japanese 20mm ammunition, dated July 1945. They tested the muzzle velocities of the Ho-5 rounds and found that the HEI did 2,400 fps, the AP-T 2,300 fps, equivalent to 730 and 700 m/s.

 Could u give me the Number of the report so that I may look it up I would love to read it,

AGW - There isn't a number on the document, it just refers to a whole page full of different reports used as sources of information.


 AGW - I think you are confusing muzzle velocity with rate of fire. The Type 99-2 had a 101mm case length, compared to 72mm for the Type 99-1. So, the mv went up from 600 to 750 m/s. I have both in my collection and they are very different!

 I am well aware of the differences in the shells for the type 99 , I have put my hand on them myself. I even refer to that in an above post. The projectiles were the same however.
 I was referring to the different marks of the Type 99 II: MK3,MK4,MK5.rate of fire ranging from 490rpm to 750 rpm, M/V ranging from 1,970ft per sec to 2,490ft per sec(model II MK5)

AGW - I don't know of any Type 99-2 loadings as low as 1,970 fps - that is the mv for the Type 99-1.

The above point aside can U tell what the comparative dispersion of the H0-5 and the AN-M2 would be at say 1,000ft then 1,500 then 2,000ft.

 Well what I was getting at is do the have a significant difference in drop at range(I could of been clearer on this point sorry)

AGW - there certainly would be, but I don't know exactly what.  I have trajectory information for the German ammo (of which the MG-FF would be a close match for the Type 99-1) but nothing for the Type 99-2.

Incidentally, if you look on my website you will find an item on the Oerlikon guns, including a family tree and a photo of all of the cartridges.

Tony Williams
New book: Rapid Fire - The Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces.
Details on my military gun and ammunition website: http://www.users.globalnet.co.uk/~autogun/

[brady]

  Mr.Tony Williams

  Ty for your post's, they have been illuminating and have got me bent on a new quest, that is to find the answers to some of the point's of conjecture above please excuse me for not taking u ay your word from the get go the Ho-5 M/V issue it is just that it contradicts every book I have and the data i got at the OMM, from US war department Tech Manual's from the period in Question, I intended to do more diging.But that is part of the fun  

                       Brady


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[This message has been edited by brady (edited 12-30-2000).]