I'm reading Koskimaki's Battered Bastards of Bastogne.  He mentions the 463 Parachute Artillery Battalion and its small 75 mm pack howitzers knocking out 8 out of 10 German tanks at Bastogne. They used hollow charge ammunition to perform the task.  I never heard of such a thing for those little guns (we had one in the SF Presidio that was used ceremonial purposes).  Can anyone tell me more about the ammunition?  I know about hollow charges, but for a 75 mm howitizer?

From the TM 9- 1300-203 Artillery Ammunition 1967

Not sure if the same round was available in WWII.

M66 HEAT round.

M66
a. General. HEAT-T cartridge M66 is a Chemical-energy armor-defeat cartridge.

b. Description. This cartridge is fixed, with cartridge case M5A1 crimped to the projectile. The cartridge case is loaded with loose M2
propellant and fitted with percussion primer M23A2. The projectile, of multipiece steel construction, contains a copper cone and shaped charge of Composition B, and a base-detonating fuze that may or may not contain a tracer.

c. Functioning. The action of this cartridge up to target impact is the same as the M48 HE cartridge, paragraph 2-127. Upon target
impact, deceleration causes the base-detonating fuze to detonate the bursting charge of the projectile, causing the cone to collapse. This creates a high velocity shock wave and a jet of metal particles that penetrate the target.

d. Tabulated Data.
(1) Characteristics.
Complete round :
Weight (lb) 15.66
Length (in.) 23.54
(2) Ballistics.
Muzzle velocity (fps) 1,000
Maximum range (yd) 3,000
Cartridge case (steel) M5A1
Primer M23A2
Propelling charge (.40 lb) M2
e. Packing Data. One round per fiber or
(3) Components.
metal container; two or four fiber containers
per wooden box.

Thanks.

The below link is a PDF of an Australian UXO memo. It specifically mentions the HEAT round for the 75mm Pack howitzer.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.defence.gov.au/UXO/_Master/docs/Types/Projectile75mmRev01.pdf&ved=2ahUKEwj2jJfx_v3qAhVHhOAKHWBPChoQFjAAegQIBBAB&usg=AOvVaw2j4mX1S_Yy0FCFOrI8nVFE

Yup, HEAT rounds were available in small numbers for the howitzers.  That was about the only way a pack howitzer was going to kill a tank.  They could get a mobility kill one one if they knocked a track off or damaged the engine but a hard kill with a 75mm HE round was very difficult.  Sometimes they'd try to use HE delay fuse but that didn't usually work.  Howitzers are low velocity compared to a tank gun of the same caliber so HEAT rounds are what they had to use.  

105mm had HEAT rounds too.  They didn't stock a lot of them per tube but they were available.