"May 7th, 1942
The work on fin-stabilized rocket propelled anti-tank rifle grenades being developed at your institute would be useful if the following performance is reached:
- Range: 200-250 meters.
- Trajectory: as flat as possible. The trajectory must not be higher than a tank's height at this distance.
- The dispersion at 200 meters must not cover an area greater than one square meter.
- The explosive filler weighs no less than 700 grams.
As soon as you receive satisfactory results, contact me, so that a representative may be sent in order to review the project and make a conclusion regarding further work.
Head of the 5th Department of GAU KA
Senior assistant to the head of the 5th Department of GAU KA
Speaking of RPGs, let's see how the first Soviet ones did. A weapons system called RPR-82 (analogous to the German Panzerschreck) was tested by the Soviets in 1941. The results were not exactly ideal. The trials are described in GAU's archives (CAMD RF 81-12040, sadly I neither have the full archive index nor the exact text of the document).
At first, the RPG (still referred to as an ATR) was planed in a trench 3 by 1 by 1.5 meters, with a dummy. After firing the RPG, the trench ended up with a crater in the rear, 1 meter by 0.8 meters, and 0.3 meters deep. The dummy was undamaged, but buried in dirt. A plywood sheet placed in the rear of the trench was penetrated and singed by the blast every time it was fired.
The next trial involved a 3 meter by 2.5 meter by 2.25 meter bunker. The barrel of the RPG was pointed outside. The room also contained a dog. After firing, the dog was unharmed, but the gases in the room made it impossible to enter without a gas mask. The dog did not appear to be suffering from poisoning by the gases.
The final trial was held in a wooden building, 4.5 meters by 5 meters by 3.15 meters. The gases from the grenade knocked out the window frame, portions of the wall, and the rear wall was destroyed by the exhaust. The concentration of gases was lower, but a gas mask was once again helpful.
The RPG looked something like this:
Aside from being unusually destructive to its surroundings, it also suffered from poor accuracy, much like pre-war attempts to use 82 mm rockets as man-portable (as long as a 40 kilogram, 6 meter long rail counts as portable) anti-tank weapons.
Now that the brief derail with rockets is done, let's get back to good old bullets. 14.5 mm seems to be a pretty good caliber, so why not put it into a machine gun?
"The machine gun will use a stock 14.5 mm round, using B-32, BS-41, BZT, MD, and other bullets.
- The muzzle velocity must be no less than 1020 m/s.
- The rate of fire must be on the order of 2000-2500 rpm.
- The practical rate of fully automatic fire should approach the maximum rate of fire.
- The machine gun must allow for continuous fire for 60-90 seconds.
- Vertical aiming angles: 10 degrees of depression, 85 degrees of elevation (90 degrees is desirable)
- Horizontal aiming angles: 360 degrees.
- Mass: total mass is approximately 300 kg, without ammunition. The machine gun weighs 90-110 kg."
CAMD RF 81-12040-253
Well, I guess that's not exactly man-portable either, but you have to find some uses for all that 14.5 mm bullets lying around.
Until, of course, 14.5 mm isn't enough. You need 20 mm!
CAMD RF 38-11369-43
The two bullets on the right are 14.5 mm bullets for the "15 P Anti-tank rifle", more commonly known as the Blum anti-tank rifle. The big one on the left is a 20 mm bullet for the RES ATR. Seems pretty good for an ATR, right? Let's take a look at it.
Once again, the bounds of "man-portable" are heavily pushed. Not only does it have wheels, it folds up for transport. The manual describes its weight as 72 kilograms in transport. Those rounds up there aren't particularly light either, weighing 0.67 kg. Each RES ATR was issued 3 crates of 8 rounds each, plus three more on the shield as an emergency supply.
The user manual claims it can penetrate 60 mm of armour at 300 meters, making it a deadly weapon against German medium tanks (or even Tigers, if you can shoot between the wheels).
And if it's not man-portable enough, it's always motorcycle-portable!
However, motorcycles are loud and expensive. Anti-tank rifles are supposed to be small and quiet, as stealthy as a regular infantryman. So why not a bicycle?
"According to order #73 AK GAU KA, NIPSVO KA must develop and test a device for carrying the PTRD and PTRS on a bicycle. As a result of trials of bicycles carrying anti-tank rifles at the ANIOP, (report #01030 from July 3rd of this year), it can be seen that this method of transportation has many deficiencies, such as:
- Riding while carrying the rifle is tiring.
- The bicycle cannot enter an incline of 5 degrees.
- The cyclist is unstable, and the bicycle cannot achieve high speeds.
- It is difficult to push the bicycle. Due to the altered center of gravity, all additional weight is carried by the pusher's hands.
- Carrying the bicycle by hand is difficult, and only possible for a distance of 5-10 meters.
- Due to the rifle sticking out by 700 mm, movement on forest trails and on sharp turns is made difficult.
NIPSVO KA chief, Engineer-Major Sholohov"