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January 05, 2007

The Whatziss from yesterday.

A British Wombat recoilless rifle at the RAF Duxford museum. 23 September 2006 Photographer Max Smith

Not too many takers on this one. Which is interesting, given that there is boatloads of data out there on this particular beast.

That said - only two takers, but #2, Pat - got it mostly correct when he identified them as rounds for the M8C Spotting Rifle. His only error (obliquely) was continuing on and tying it to the 106mm recoilless rifle.

These were used for the M8C rifles used on the British Wombat recoilless rifle - a quibble, certainly, except the red paint in the flutes indicates their Brit origin.

This website (the Armorer wants one of these guns) has a nice set of pictures of a before and after restoration of a 106RR.

The spotting rifle is used by the gunner to acquire his target, without wasting main gun ammo, and with a lessened signature to give away his position. The M8C is a gas-operated semi-auto, which means the gunner just pings away with it until he sees a hit on his target at which point he fires his main gun. The use of a special cartridge with the M8C, vice a regular .50 cal round, is because you want the ballistic performance of the round to be roughly equal to the trajectory of the main gun - speed of flight isn't as important as trajectory matching is.

Tanks can use their coaxial machine guns for the same purpose. The Israelis even mounted M2 .50s on their M109A1 155mm howitzers for the same purpose - to make it easier to use the guns in direct fire mode.

Now for the fun part - doing some research for this post, I found this very nice picture of an M50 Ontos - the USMC reckless rifle carrier of the Vietnam era.

M50 Ontos

And I found this website with a lot of great pictures of the Ontos, certainly one of the odder weapon systems we've developed over the years. A lot of firepower on that little tracked chassis - but all served from outside the vehicle, on a vehicle, by the very nature of the weapon, that is going to attract a *lot* of attention.


Comments on The Whatziss from yesterday.
haji 0 matic briefed on January 5, 2007 08:44 AM

I just watched a CBS set of DVD's of archival reports from Viet Nam...starring Walter Cronkite (and seeing a young Dan Rather and a Charles Kerault) During the Tet offensive and battle of Hue they showed a curious contraption scuttling about the city shooting at things. I Googled and fount the Ontos. (Greek for THING). Firing a beehive round (flechettes) it could do a better job than artillery penetrating the jungle. However...the crew did have to get out of the armor to re-load the thing...
I have always thought the recoiless rifle was given a premature retirement...

wolfwalker briefed on January 5, 2007 09:08 AM

Oh, wow. That "Ontos" thing produced an instant flashback to the MechWarrior computer games. It looks like a BattleMech that was designed by somebody who just wanted maximum firepower, and didn't give a darn about speed, mobility, ammo supply, or anything else.

SangerM briefed on January 5, 2007 10:05 AM

Great weblink!! I spent two "seasons" at Pohakaloa. The first time ('75), our unit still had 106mm RRs. The seond time ('76), the 13 jeeps of the AT platoon had been traded for 25 jeeps of the TOW platoon. That was where I first saw one of those things fire. Also, BTW, the first time I ever got to see real WP fired downrange and live ordnance dropped from planes.

I got to fire a 106 one time. It was just unbelievably thrilling! That is one big noisy gun and you are leaning over it when you fire. Push-pull. (or vice versa, I can never remember...) KA-EFFIN-BOOM!!!!

And I always wanted to fire an ONTOS, but I never saw a real one. Also, the two bottom guns were supposedly ground mountable. The loader had to get out of the vehicle to load the guns from the rear. The 6 guns were attached to a swiveling TC turret; all he had to do was point the center mounted 50 at the target and the guns were aimed. Crappy little vehicle, immense defensive firepower, at least once...


J.M. Heinrichs briefed on January 5, 2007 12:21 PM

Generally, tankers don't use the coax for ranging as the GPMG is not a good MV match for a 105 or 120mm. The Centurion and Chieftain used 50cal Ranging Machine Guns (no trajectory matching) before the arrival of Fire Control computers. Firing a burst (3 rds) from the RMG gave the gunner a complete firing solution; he would then select the appropriate aim point for the main gun and fire. The major limitation was that the 50cal could reach out to 1800m but the 105mm Sabot was effective to 2500m, the 120mm to 3000m+.

Trajectory matching worked with the 106mm as the relative MVs were similar. As for the Israelies. they also mounted 50cals over the main gun to engage targets which could not be handled by the coax, but didn't rate a 105mm round.


MajMike briefed on January 5, 2007 12:39 PM


that whatziss just went from zero to bodacious in one post.

way cool.

Trias briefed on January 5, 2007 10:29 PM

The Ontos looks like it belongs with those Battlehammer games.

SangerM briefed on January 6, 2007 08:56 AM

Oops, center mounted .30, not 50.

I also got to drive an M60A1 (RISE, Passive, etc.) during a gunnery season in '79 (couple months of prep and do), we scored green at Graf, and I got fire it one time. Wasn't as much fun as the 106mm, but when I drove, I sometimes left the hatch open or cracked, and THAT was a kick in the butt when it fired. Well, except for 2 times:

1) The turret was turned to port and the .50 shells started falling into the driver compartment, one went down my shirt back. HOT! OW! That was a LOT of shells.

2) I used to drive with the hatch open, but not locked into place to my right. One time, while we were engaging night targets to starboard w/ the CoAx, the road canted sideways, with the slope downward to port. The well-lubed hatch slid downward and pinned my head between it and the hull. How I managed to get that thing pushed back uphill and locked into place AND didn't ruin the engagement or turn the tank, I'll never know. And Thank GOD and NATICK for CVCs. And in '79, I was wearing the 'new' one that had the shell over the padded headpiece, not the full helmet. Slight headache, strong memory of being really stupid.

John of Argghhh! briefed on January 6, 2007 09:04 AM

I used to drive with the hatch open, but not locked into place to my right.

In an odd cascade of associations, Sanger - the first thing that popped into my head when I read that sentence was "canted" - which, the story coming from you, is oddly appropriate.

SangerM briefed on January 6, 2007 07:15 PM

That got a good laugh... Thanks for noticin'

And yeah, I know.

Believe it or not, that has been mine since '2000, and it used to have a full structure. I'd started reworking it in Dec 05, after I got TGR done but that got put on hold until after I get done with school. The plan is to use it for different kinds of stuff than TGR, more...personally skewed... :-)

Justthisguy briefed on January 9, 2007 12:19 AM

Oh, BTW, guys and gals, if you poke around on that restoration site some, not only will you see some other cool pieces, but some cool French Postcards, as in, like the proverbial Platonic Ideal of the French Postcard. Very risque to us Merkins when issued, but tamer than some things in kids' books these days.

O Tempora, O Mores!

(Translation: Back when I was a kid, we didn't get to look at that kinda stuff. Dammit!)

Outpost37 briefed on January 9, 2007 08:38 PM


Well, now, I'm confused. One of my college room mates said he was assigned to be an ONTOS driver, but he was in the D.C. National Guard. Perhaps the Army was phasing them out, and, as usual, the Marines got the castoffs? Ditto, the Guard?

John of Argghhh! briefed on January 9, 2007 08:43 PM

The official Army position is here.

That said, we never did adopt the Roland missile system - but one National Guard ADA battalion did get it for a while.

Might be the same thing with the Ontos.

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