Reply to post #125
Herman,
1) The APDS projectile for the 75mm SA-50 gun was extensively tested but remained experimental and was never type-classified. This is due to the French fixation on 'Obus G' at the expense of subcaliber projectiles.
2) The SADF had to develop the APFSDS projectile for the OTO 76mm/62 no matter what and apparently modified the gun itself to accommodate higher working pressures. IOW, starting from scratch could not be avoided, either with the OTO 76mm or with the French 75mm.
3) Quite a few pics of the South African 76mm APFSDS have emerged recently (including high-res cutaways) and the Israeli input in the design of the projectile seems quite obvious. Pictures of the 75mm APFSDS used by Singapore are more difficult to find, but based on whatever I've seen so far, the design looks very similar (at least externally) to the South African 76mm APFSDS. I believe than Israeli involvement in the design of the 75mm APFSDS is common knowledge.
4) As far as the 105mm Mle 57 is concerned, I mentioned it as an option because a) NORICUM of Austria (part of it being Hirtenberger nowadays) proved quite "flexible" when it came to sanctions and b) it's a rifled gun (32 RH @ 7°10') which AIUI is what the SADF had a preference for.
5) While MECAR didn't have much to offer before the introduction of its KENERGA 90mm/46 (1982 IIRC), you may be quite right about the Cockerill MkIV 90mm gun (though I couldn't find the exact date of its introduction). That said, APFSDS only became available with the Cockerill MkVII (introduced in 1983 IIRC) and, - despite similarities -, ammos were AFAIK not interchangeable between the MkIV and the MkVII. Meaning you still would have to develop an APFSDS projectile, which in this specific situation was never developed by anyone (Brazil apparently never really bothered).
This leads to a very last observation : I've never been able to find a brochure showing the range of projectiles available for the 76mm GT4; neither have I been able to locate some detailed spec sheet for the gun itself (with such details as the working pressure, rifling twist & grooves, chamber volume, etc...).
Are these infos classified or did I simply fail to locate the place where they might be found ?
PS : I corrected a typo in my post regarding the APDS used with the QF 17 pdr (wrote 2.5kg instead of 3.5kg for the projectile's mass). The data I have for the APDS 1T is 7.625 lbs for the mass and 3,950 fps for the muzzle velocity.
Edit : Development of the Cockerill MkIV began in 1978. Approximately 32 units produced, of which 22 units for Uruguay's M41 upgrade. The MkIV fired the NR-232 APFSDS projectile.