The USA Rifle grenade was designed to take out light medium tanks..ie- 251's, pz III's, pz IV's?

I think they fielded a couple of different types of 'warheads' and AT was one of them. Don't know common they were in use for the AT role.

Yes. The designer of the bazooka took the standard antitank rifle grenade warhead and mated it with a small rocket motor.

How much RHA would it be able to penetrate on average?

The US M9 HEAT AT Rifle Grenade could penetrate over 2"
http://inert-ord.net/usa03a/usarg/rg/index.html

Al

It's not clear what you are asking . . . The purpose of antitank rifle grenades is obvious, but there were other types of rifle grenades like fragmentation and smoke.

KL

It was designed to penetrate armour. About 2" apparently, so what it could "take out" depended upon where you hit the armoured vehicle.

A rifle grenade round could "take out" a King Tiger if it impacted any of the horizontal surfaces, all of which were under 2" thick.

The rifle grenade rounds were actually more useful in that regard than bazooka rounds as the bazooka rounds were generally delivered against the more vertical surfaces, which were more highly armoured. The rifle grenade rounds were like mortar rounds and were plunging fire, more likely to hit the lightly armoured horizontal surfaces.

The rifle grenade round was not designed with particular targets in mind.

Paul

Rifle grenades have rather poor chance of hitting a tank's roof with plunging fire unless the rifleman is firing downwards from a tree or a upstairs window. If he is there a bazooka would do just as well.

If he is firing from ground level where a bazooka can't hit a tank's roof, the rifleman would have to get both the range and elevation right to hit the tank's roof, and there is precious little chance of that unless the tank is stationary and the rifleman can correct his fire by firing several times.

Btw, I thought a bazooka can go through more than 2 inches. I believe they can take out a tiger 2 from the side, and that's at least 3.5-4 inches.

[quoteBtw, I thought a bazooka can go through more than 2 inches. I believe they can take out a tiger 2 from the side, and that's at least 3.5-4 inches.[/quote]

The 2.36-inch M6A1 HEAT rocket could penetrate 3 inches of RHA (OS 9-69, FEB 44). The M6A3 could penetrate 5.3 inches while the M9A1 rifle grenade could penetrate 4 inches (NAVORD Report 1248, 17 AUG 50).

KL