LAV-75; Stingray; M8 AGS

[dragoon500ly]

Originally Posted by Webstral

So true! I'm certain that the supply types would be making almost exactly your argument against a 105mm variant of the LAV-75. The maneuver generals will reply in two ways: a) the fighting in the Far East has shown that light forces need stiffening with airmobile armor and b) the supply people are never going to get behind anything that makes their job more difficult, regardless of what that means for the troops actually doing the fighting. The former probably would be true. The latter is cheap shot, although there's a grain of truth in there. The logistics specialists have been a driving force behind commonality of supply since WW2 for good reason. Nonetheless, the "fighting" generals will attempt to discredit the arguments of the supply types if the maneuver commanders become convinced that an FSV variant of the LAV-75 is needed. The real question will be whose voice gets heard.

The real point of the argument is why a 75mm at all?

A lot of this material comes from various Armor Journal articles as well as the Congressional Record.

When Germany decided to introduce the 120mm smoothbore, the US Army did not want to upgun at all. The viewpoint was that the 105mm M68 rifled cannon was the ideal tank weapon. Since it was capable of performing the antitank, direct and indirect support roles, there was no need to upgun as continued development of ammunition and propellent precluded any need to switch to a heavier weapon.

Congress mandated a gunnery trail between the two calibers. Needless to say, the 120mm out performed the 105mm using the standard APDS round. This led to the rushed development of the APFSDS round and the next round of trials had the 105mm out performing the 120mm, that is until the APFSDS 120mm round was developed. Faced with their gun falling behind, the US developed the APFSDSDU round, the first depleted uranium penetrator and the 105mm took bragging rights, right up until the 120mm APFSDSDU was developed. By this time, the object lesson had finally sunk in, 120mm was superior to 105mm in the antitank role.

BUT WAIT! The 105mm was superior in the direct and indirect support roles! Every US tank gunner from WWII on has been carefully taught how to use their cannon to fire support for the infantry; it was the primary purpose in the big war as well as Korea. Vietnam had no documented use of tanks in anything other than direct support, but this was widely believed to have been due to the small numbers of tanks in theater. So the next round of gunnery trials included indirect fire.

The 120mm gun turned out to be a poor performer. But to the shock of the US Army, so did the 105mm! It turned out that the very quality that made for an effective antitank weapons, i.e. high-velocity rounds, also made for major problems with indirect fire, quite simply an "excessive latteral dispersion contributing to impared accuracy", in other words, the HEP rounds landed all over the grid square!

It was shortly after this third round of trails that US tankers saw the withdrawal of HEP, WP and Beehive ammunition as well as the removal of gunner's quadants and azumith indicators from the M-60A1/A3 tanks.

The 105mm/120mm gunnery trials also led to the NATO consenus that the smallest effective caliber for tank armament is 90mm. The need to comply with the "NATO Standardization" provisions of the charter are, almost certainly, what killed off the 75mm cannon development.

My own personal opinion is that the LAV-75 would never have seen service in any capacity. With the need to comply with the minimum of 90mm, and with tens of thousands of 105mm barrels and thousands of tons of ammunition in storage, the US Army would have gone with a 105mm version almost certainly from the start. This version was known as the M-8 AGS.

So, in many ways, the bean counters would have won the argument, but in such a way as to insure the support of the line dogs.