90 & 105 mm recoilless rounds

I came across these images of recoilless rounds and wonder if anybody has more or better info on them.

90 mm HE-FRAG XM591, adapted 81mm mortar shell. Recoilless rifle M67.

105 mm HEAT M341. Recoilless rifle M27 & M27A1.

SInce I’m new to the board, I’ve been going through the old posts. To answer your question EOD, I’ve never seen any of the 90mm with an 81mm adapted to them, but I have see plenty of the HEAT version. The fuzing on the 81mm looks to be the M524 series, which tended to dud often with the 81mm mortar and create a down range hazard, because even as a dud, it was touchy with a free floating det slider. Something you didn’t want to accidentally step on or jar.

The 105mm M341 was used, but the only time I ever saw one was on a Range Sweep at MCB Quantico in '84 or '85. Took alot of digging in some of the older pubs to find it. If I remember right, the fuzing was the M509 series Point Initiating, Base Detonating (PIBD) Lucky Crystal (Piezo Electric), and if not, something very close to it. I’m almost positive that it didn’t have the M530 series PIBD (pretty much the same as the M509 with a graze sensitive (impact inertia) feature). I’ll look in my pubs some more, but to date, I haven’t found it yet.

Seeing these RCL rounds takes me back to 1972, when I was the attached Medic to a UXB team clearing Artillery Ranges of unexploded shells ( “Blinds”).

Most of our “Blinds” were the 106RCL Finned Rounds, with Piezo Fused initiators.

The Usual cause of the “blind” was a “glancing shot” whereby the shell hit target at an acute angle, ricochetted up into the air, and then fell back to earth without detonating…the other cause was a “belly landing” shot, where the shell just ran out of energy and slid to earth, without hitting anything solid to detonate it. ( especially after a tropical downpour.)

As the "condtioin " of the Piezo crystals were unknown, and even a slight jar or shake could send current down the capacitors and ignite the detonator,
we always treated these “Blinds” with extra care.
Once the item was ID’ed as a 106, we gingerly paced a fuzed block of C4 next to it, as close up as possible, covered the block with a couple of semi-filled sandbags or just loose dirt, and once all team members except the Shot-firer were well clear, a pre- measured length of Safety Fuse was ignited; the Shot-firer then Walked briskly back to the protected Position ( Trench, Hollow in ground, large Logs, etc some 50 metres or More away from the Blind, along a track pre-cleared and Timed by the Shottie himself, and everybody else ( further away) hunkered down awaiting the explosion.

Once the Explosion went off, we moved forward to ensure that the Blind had actually “gone off”, and to check the area for any other “blinds”.

Procedure for “Blinds” during Training Fire was for them to be “noted” on a Grid map, and then when the training was finished, the Range manager would go and “mark” them with a Flag; then a UXB team would either “clear” the Blinds after training, or in the case of Blinds Found between Range days/weeks, Before New use of the Range was undertaken.

During these " Blind clearing" sessions, I attended the destruction of 105mm Art. Projectiles, 106 RCL, 76mmQF, 3,5 inch RL, 2 inch and 3 inch Mortar bombs, numerous Energa rifle grenades, and the Occasional ENTAC wire guided AT Missiles ( the wire from these was a real pain, (figuratively and literally) as it littered Range areas, tripped you up, and in a rusted state, easily cut your hands deeply.)
One large area of UXBs was the target area of a 2 inch Mortar excercise, into Ground softened by days of Rain. Most of the Bombs did not explode ( 1944-45 manufacture) as they buried themselves into the solft ground ( clay) which by the time we got there, had hardened. All that usually showed was the tail fins…so we blew up tail fins all day ( most were live,some were just the fins…we must have blown over a hundredweight of C4 that day.

Doc AV
AV Ballistics.

That’s exactly what I did, but from the engineer side. Placing the charges could sometimes be a bit tricky, but the end-result was always fun. I did mostly rifle grenades, mortar rounds, and mines. By the time I got into the IDF all the 106 RCLS were gone.

I found it, kinda. There was a 90mm HEAT developed for the tank gun that looked and operated like the 105mm RR, just scaled down. Inside of the 90mm case were rails for the fins to sit in so when the round was fired, the fins wouldn’t bang off the insides of the casing. The fuzing was the M509 for it, the 105mm HEAT RR, the 90mm HEAT RR and the 106mm HEAT RR (plus some other heat rounds).

The publication I got it from was the TM 9-1300-203, Ammunition for Anti-Aircraft, Tank, Anti-Tank, and Field Artillery Weapons dated August 1960.

I tripped across this old post, EOD did you ever get an proper answer on this? Yes, the US put an 81mm body inside of a 90mm RR. I’ve only seen one reference on it, and the items are kind of scarce. I’ve only got one, I’ll see if I can dig out any pictures.

Best picture I’ve got at work. I was thinking XM571, you stated 591. I’m going by memory, but are you sure? Item is roughly center, beside the 106mm.

yesterday the 2010 images did not open, I assumed they were among the lost historic data that plagues the early posts. Today, however I can see them (?) and things are much more clear. XM591 seem clear, my memory is slowly slipping. I’ve included more of the cropped image since you also (a decade ago) asked about the 105mm HEAT. I’ve got about 1.75 of them, a complete one on the bottom right, and the warhead section on the shelf above, including a set of range recovered fins.