M27 105mm Recoilless Rifle in obat12

[Basileus Ioannis]

Hi team -

Thanks again for all the work you do, I appreciate it. I haven't seen this topic in a search, so again please disregard if it has been discussed.

I just want to shine a spotlight on the M27 105mm recoilless rifle in obat12 (unit 261). It was adopted for regular infantry battalion heavy weapons companies with T/O&E 7-15 change 1 dated 30 September 1952; but the 187th Airborne Regimental Combat Team, dissatisfied with the bulk of the T8 90mm antitank gun, jumped without the T8s (replaced in the regimental support company with a third 4.2-inch mortar platoon), and replaced the 75mm recoilless rifles in the battalion heavy weapons companies with 105mm rifles, on their second combat drop at Munsan-ni on 22 March 1951. This is the earliest reference to the 105s I could find.

The M27 105mm recoilless rifle was mounted on a jeep, like the M40 series 106mm that replaced it; both could be demounted, the M27 105mm having a two-wheeled mount and the M40 106mm having a tripod with a single wheel on the front leg. The few references I've found on the 105mm in action show that it was fired from the mounted position, with a dedicated four-man crew on the jeep.

Regarding its replacement, the 106mm M40 was standardized in October 1954, and authorized with T/O&E 7-15R of February 1955. Knowing how long things take to field, especially during the lean Eisenhower years, it is conceivable that the last of the 105mm M27s didn't get replaced in active duty infantry battalions until the ROCID (aka Pentomic) TOE of 1957-58. The February 1955 T/O&E concurrently replaced the 75mm M20 recoilless rifles, making the recoilless rifle platoon 106mm-pure, but I don't know if it was a four-gun or six-gun platoon (leaning toward four-gun with reduction in manpower...a lot of that going on during Ike's administration). If you have a copy of this T/O&E, I would greatly appreciate if you would share it, thanks

John

[Pfor]

Interesting information.

Until now, I had assumed that the M40 was authorized by TOE 7-18 Change 5 on 14 October 1954 rather than by 7-18R, since the R-series seemed to change precious little in most cases.

In any event, in 7-18R the M40 platoon was authorized 6 106-RR on jeeps in 3 sections of two.

As to the M27:
a) the original authorized description was 'Rifle 105-mm on mount M75', and everything I found said that the M75 mount was permanently affixed to the jeep due to its heavy weight;

b) the earliest reference I came across was TC-31 4 September 1952, which described itself as an interim document pending release of official training docs and FM.

[DRG]

OK, so now it's a "105mm RR Jeep" 3/51 - 2/55

[Basileus Ioannis]

Originally Posted by Pfor

Interesting information.

Until now, I had assumed that the M40 was authorized by TOE 7-18 Change 5 on 14 October 1954 rather than by 7-18R, since the R-series seemed to change precious little in most cases.

In any event, in 7-18R the M40 platoon was authorized 6 106-RR on jeeps in 3 sections of two.

(snip)

Thanks for the enlightening info; my copy of 7-15 only shows up through change 4 dated 25 June 1954, I didn't realize there was a change 5. Since T/O&E 7-15 from September 1954 was the ATFA test, the very next T/O&E I saw was the February 1955 Revision. Thus apparently change 5 was issued as soon as the M40 106mm was standardized...still, fielding would probably have taken quite some time, as we weren't in a shooting war at the time. Assume field testing in CONUS using change 5 T/O&E for at least a few months before the first shipments sent overseas, perhaps December 1954 at the earliest, more likely summer 1955, but they would be available for deployment should either the Korean or European theater became hot. As far as Korea, R.P.Hunnicutt mentions in his book PATTON that terms of the armistice limited fielding of new equipment, hence their retention of M46 Pattons after they were declared obsolete in February 1957; this may indicate that 1CD and 7ID in Korea didn't receive the M40 106mm for some time, perhaps even after the Pentomic reorganization. Would you have any info on that? Thanks,

John

[Basileus Ioannis]

Originally Posted by DRG

OK, so now it's a "105mm RR Jeep" 3/51 - 2/55

Thanks Don, but please stand by on the end date, still trying to establish how long it took active duty units to wash out the avalanche makers.

John

[Pfor]

Sorry, but I don't have much to contribute in the world of actual unit MTOEs and equipment service dates, preferring to stick to army-wide authorization and School documents (academia if you like).

In ROCID (T-series), the 106s were supposed to be pushed down to the companies (2 per) and the renamed Assault Platoon had 2 sections of 2 units each of either 90-mm tanks or 90-mm SPATs (Scorpions) while waiting for the DART ATGM - which never did arrive.

[DRG]

Originally Posted by Basileus Ioannis

Thanks Don, but please stand by on the end date, still trying to establish how long it took active duty units to wash out the avalanche makers.

John

I'll just make the end date 12/55 for now. A little longer or less doesn't make any differnce to the formations that used them but we've all missed the 75mm M20 RR Jeep for years and that allows the Mobile RR formations to got back to 1946 so that's in the OOB now.


Don

[Basileus Ioannis]

Originally Posted by DRG

I'll just make the end date 12/55 for now. A little longer or less doesn't make any differnce to the formations that used them but we've all missed the 75mm M20 RR Jeep for years and that allows the Mobile RR formations to got back to 1946 so that's in the OOB now.


Don

Roger Don, thanks. Re: the M20 75mm on a jeep, is that from the June 1945 T/O&E? The 1948 T/O&E shows two M20 75mm on tripods carried on one 3/4-ton Weapons Carrier truck per section, two sections per platoon, and only one jeep in platoon HQ with a .50cal AAMG. In T/O&E 7-15 change 1 dated 30 September 1952, they deleted one M20 75mm from each section, and added two M27 105mm jeeps to each section (2x75mm, 4x105mm platoon total). I had often wondered what happened to the 75mm RR jeep since I saw the ROCO 1/87th scale model of one as a kid; recently I found a web page discussing the French army use of 75mm RR jeeps. Thanks again,

John

[Pfor]

Re 105mm RR Platoon, attached is from Training Circular 31, dated 4 September, 1952.

Re 75mm Jeep RR, this is not in TOE 7-18 dated 1 June 1945. My best guess is that it was either Airborne only, or an unofficial mod.

[Basileus Ioannis]

Thanks Pfor, this info is exactly what was missing in my research (need to make a trip to Carlisle some day...). So my assumptions (based partly on US Army Forces in the Korean War 1950-53 by Donald W Boose, Jr.) were incorrect, they didn't mix calibers in sections nor did they leave only the two sections, but eliminated one 75mm section and added two 105mm sections, which would later mesh neatly with their conversion to three identical 106mm sections with the Change 5 you enlightened me to.

Re: the section HQ with 3/4 tons, do you know how long they kept these? I wonder, because the subsequent G-series TOE seem to indicate only a section leader with no vehicles (after the ENTACs were replaced by 106mm until fielding TOW), and I couldn't imagine him staying behind on foot with subsequent loss of C&C capability, nor could I imagine him hitching a ride on an already encumbered squad vehicle...and yet, when the TOW was fielded later, they end up in sections of two firing vehicles and one C&C vehicle (in mech units at least).

btw Outside of paying Carlisle a visit, would you know a good source for H-series TOEs? That's always been a gap in my research that I've had difficulty filling...thanks again for the info

John