Basically a 105mm choked shotgun. I would NOT want to be on the receiving end. Beehive fires forward and the time fuze (Killer Junior), sends blast in all directions. HOWEVER, neither of these were in use in WW2, to my knowledge, and only date from Vietnam.
The Beehive rounds had to be fired in direct fire mode, and were meant as self-defense measure for arty units set up in the field. In order to have any effect, the barrel had to be lowered to almost horizontal level, where then the shell would release 6000-8000 flechettes (iirc), when the time fuze would go off. That means that the flechettes flew in a relatively straight line (say at head or upper-torso level), so that crawling/prone enemies could not be hit.
In turn, the Killer Junior method was only used in conjunction with regular time-fuzed HE rounds and was only used in
direct-fire mode, as well:
The arty crews fired time-fuzed HE rounds using only slightly curved trajectories and they chose particular time delays on the fuzes so that the rounds would detonate at around 9-15 meters above the ground, at distances between
200 meters and
1,000 meters from the gun position. Obviously, this was a method for defense, as well. The advantage here was that the explosion (and shrapnels) would travel in all directions, so they could hit prone enemy troops or enemies behind (hard) cover. The Killer Junior and Senior methods were both timed
air-burst shots.
The
Germans extensively used
air bursts in
WW2 after they had developed the method on the Eastern Front against RU troops hiding in woods and wooded marshes, as
indirect-fire method. By 1944, the Germans had mastered the method, which (usually) involved regular indirect fire with curved trajectories, where then the units computed the travel time of the shell, wind speed/direction etc. and applied the corresponding fuze settings, so that the rounds would go off above the ground. The Germans also used the method extensively on the Western front, particularly during the Hürtgen Forest Battles (in a defensive manner) and punctually during the Ardennes offensive (eg. around Bastogne, iirc, in an offensive manner). The method made foxholes less effective and the air bursts also created a myriad of splinters in wooded areas, which led to a lot of casualties on the Allied side.
So, indirect-fire air bursts were extensively used by the Germans in WW2 (as offensive AND defensive measure - where the defensive type was mostly used on rather fixed fronts, afaik), but close-proximity direct-fire air bursts for self-defense became popular in US units deployed in Vietnam. Since the Germans also used air bursts against RU troops in trenches in indirect- and direct-fire missions, I wouldn't say that US units invented the air-burst technique (at all).
You could say that they were the ones that started (or had) to use it (at close range) extensively during defenses, when threatened to be overrun by Vietcong or NVA.
Since the Germans loved & mastered their HE time fuzes/air bursts, I could imagine that some arty units used
direct-fire air bursts for defense locally/punctually, too, but I don't know any particular reports (they may be out there, though) describing a Killer Junior defense. Many barrels on German arty pieces had depression limits, eg. 600 meters on some 10.5 cm arty pieces, for instance, so a Killer Junior would have had to be started way out, say at 1,000 or 1,500 meters, but that's a distance where arty units could still try to escape, where they would just trust their impact fuzes or where they could call in neighbor. arty units or even mortars.
I was unable to find any specific info on a German 10.5cm APERs round that might have been used. Hopefully someone else can answer that part.
German 10.5-cm Flak 38 and Flak 39 guns used HE + AP (tank) grenades, the HE shells were equipped with time-fuzes which could be set by the Kommandogerät (command device, an analogue computer that also considered windspeeds/influence of winds determined by the weather platoon), those values were then - along with the pre-aim data - electrically transmitted to the individual gun positions. The fuzes were then set by a device on the gun which had received the time fuze settings. The gun-laying data (elevation/angle) went right to the gun-laying device of the gun (supported by E-engines), which then aimed automatically. The guns also had loading and ramming devices, so the loaders just had to put the rounds on the loading tray. The HE shells would often pierce through a bomber (due to the missing impact fuze) & then explode above/behind the Bomber, with the bomber (often) still being operational. With the introduction of additional impact fuzes, AA units managed to triple their kill rates, but those dual-fuzes from Junghans could not be delivered before very early 1945. Only HE + AP were used/available, afaik.
German 10.5 cm field howitzers could fire 48 different (models of) rounds, which belonged to more than 10 different classes:
- HE rounds with either impact fuzes or time-fuzes (but dual-fuzes were pretty common here, afaik) with the HE amount ranging from 1.4 kg to 2.3 kg),
- HE-incendiary combo rounds,
- smoke rounds,
- rounds with chemical warfare agents (some called "Buntrauch" rounds = "colored smoke", to camouflage chemical grenade and rocket stocks),
- marker rounds,
- The Panzergranate version for the FH, which was either a regular AP(BC) or an APCBC-HE-T (with tracer) round (if the description in a le.FH 18 manual/pamphlet actually refers to the available 10.5-cm Pz.Gr. as Pz.Gr. 39, then it would be a variant of the latter round, means a variant of the tank round "Panzergranate 39", but I do not know if the comparitively low velocity of the gun actually provided enough punch to fire the PzGr 39 APCBC-HE-T rounds with a suffic. accuracy),
- Pzgr 39 T S, with very small amounts of explosives (20 g); TS = "Treibspiegel", the term usually describes a method where additional powder - which sits between the propellant and the under-calibre bullet - seals the gap between the barrel and the bullet in ancient guns, so the TS round might have been a Sabot round, actually,
- HE TS rounds (10 cm Sprgr 42 T S with 900 g of explosives),
- dummy rounds for training or parades (no HE, no propellant),
- rounds for training (with propellant, but only a small amount of HE, either with 66 g, 150 g or 400 g of explosives),
- hollow-charge rounds, used against tanks, EDIT: these were regular rounds, not over-calibre rounds,
- illumination rounds,
- BL rounds ("blind" rounds, no explosives but filled with tar),
- "Anschieß"-rounds (used to test guns on testing/factory grounds or when either the barrel or the sights/optics had been replaced at ordnance or in the field).
- "White-red" rounds filled with 0.5 kg propaganda leaflets (lol) .
Afaik, there were no flechette rounds or any similar development attempts.
The Germans worked on handheld-AA solutions, which used multi-barrel solutions called "Luftfaust" (= air fist) with 3 barrels and the "Fliegerfaust" with 6 barrels (= aviator fist) which could fire 2-cm and 3-cm rocket-propelled "Minengeschosse" (= "mine" projectiles) at attacking combat aircraft, from a soldier's shoulder, propably similar to the handling of a modern javelin/stinger.
The 2-cm projectiles of the Luftfaust reached a velocity of 380 meters/second and the weapon had no recoil.
Since the Luftfaust's spread was too big, the number of barrels on the successor the Luftfaust-B was upped to 9: Those 9 grenades were fired in 2 salvos with a spacing of 0.2 second and they created a hit box of 60 meters at a distance of 500 meters.
10,000 Luftfausts with 4 Million rounds were ordered in March 1945, but only 80 pieces were listed as field trial weapons in April, so it can be assumed that a full serial production never started or that the first serial batches never reached the remaining combat units.
After reading your description of the flechette ammo used in Vietnam, I start to think that those Luftfausts could have been used as "flechette weapons" against infantry.
The Germans also worked on hand-held AA-rocket launchers, where some of them were supposed to launch 97-mm rockets that would then release 7 innovative smaller rockets (with 30-mm rounds attached to their tips) after the launch, where then their offset nozzles would create a kind of shotgun shot. The offset actually was arranged in a way that these 7 rockets would go in circles within a 100-meter radius, if they didn't hit anything, which eventually created a cloud of flying rockets within a box of 400 meters. The impact fuzes were highly sensitive, so even brushing a plane would have set off such 30-mm round.
The initial 97-mm round was supposed to be fired from a pipe similar to the Panzerschreck. The development started in January 1945, but the developers were still busy with small-scale studies examining the needed flight paths for the small rockets and with developing the actual mini-rockets at the end of the war, so there wasn't even a prototype.
It seems like they never came up with the idea to use such weapons against infantry.
A large version of the Luftfaust called "Föhn" contained 35 rails that fired 37-mm HE rockets (range: 1,200 meters). Later versions fired 55-mm rockets (48 rails) and 73-mm rockets (28). By November 1944, around 15,000 rounds had been fired during combat field tests, but only 1 plane was actually downed. In December, the Germans managed to shoot down 2 Allied planes, but they had to fire 5,000 rounds for those 2 kills. That means they fired 70 salvos just to score 2 hits.