Factory Sectioned 120MM's - M865 TPCSDS-T & M831 HEAT-T


#1

I want to share some photos of two new, 100% inert, factory sectioned 120MM tank rounds for the M1A1 Abrams Tank that came to me via Pepper who I am very grateful. They even have simulated powder. They are absolutely beautiful and really show in great detail the complicated nature of these two rounds design and fabrication. I am pretty excited if I must say :-)

This is one of the very first type classified versions of the M865 TPCSDS-T (Target Practice Cone Stabilized Discarding Sabot Tracer) rounds. It has had many adaptations over the years, primarily to its sabot petals, stabilization cones and the method the projectile assembly is attached to its combustible case.

This is the “Long Sabot” version with ported cone stabilizer.

This is the M831 HEAT

I love the way they designed the CCC case to attach to the projectile


#2

Very, very nice rounds. I understand you are excited about these sectioned cartridges.

Any thoughts about how they filled the CCC cases?
Do they still have headstamps like these?(I only :( have the pictures. )



#3

Western
Purely from a mechanical point of view, it looks (to me) like they borrowed the British Cordite loading method of forming the “neck” & shoulders after inserting the powder and “dart” section, than folded over the mouth before adding the threaded “lock ring” to the front of the dart.
The “warhead” could than be threaded onto the front of the dart as needed.

Jason
Beautiful pieces, thanks for sharing.


#4

Thanks Tailgunner. That makes sence to me.


#5

Yes, those are the correct headstamps for fielded M865 and M831 rounds. The “Models” that I have are unstamped/stenciled as are the other 120MM display models in my collection. I have a few different aft caps from fired 120MM rounds with CCC cases that are all stenciled to match their type classification like the ones you show. While I have never seen the entire manufacturing process for these types of 120MM rounds, the few photos that I have seen of the assembly process shows the case in two parts. The case shoulder is a separate part which is first attached to the projectile, then the shoulder and projectile are fitted to the rest of the case. Still, the more I look at these rounds, the assembly still puzzles me. I would LOVE to see a video of the entire process one day.

Jason


#6

Jason
No join line between the body and the shoulder (at least on the M831).
It’s possible that the case body/mouth is formed, the dart and powder inserted before forming the base folds and attaching the “case head” (same basic load than form process), but that may lead to some “detachment on firing” issues (unlike a combustible case, which is consumed in firing)


#7

This is the general assembly concept of most of the 120MM APFSDS rounds that I have seen and some of the early HEAT rounds with a CCC case. I just looked super close at the M831 and you are totally correct, Tailgunner, that there is no join line between the body and shoulder and the CCC case looks to be one piece.

Jason

This is the M829 APFSDS assembly poster. An interesting fact that I just learned from a new friend that I made who used to work testing tank ammunition is that early on in development some cases had the shoulder fit “Inside” the case body. Today all CCC cases have the shoulder assembly fit “Over” the main body of the CCC case. He told me that in one case in Germany, a Leopard tank crew loaded a slightly imperfect case in the main gun and the join-line lip caught on the edge of the gun while being inserted. The crew was shooting round after round and somehow the CCC case ruptured from the join-line and a hot ember or surface ignited the round outside the chamber causing the fatalities (RIP). The hole accident was blamed on the shoulder assembly snag and ever since the shoulder assembly is now glued to the rest of the case on the outside. HOPE THAT MADE SENSE???


#8

Jason, the documents I had seen are not good enough to judge to 100% by the drawings but to what I have seen the shoulder section is going over the case body (means it will be hard to catch a loose lip and rip the case open) in all German 120mm models satrting with the DM13 and still being the same in the latest DM63.


#9

True! Apparently, it was an accident when testing a early model, maybe before it was type classified and put into full production? Every CCC case that I have seen have the shoulder “over” the case to prevent snags when loading. It is amazing how many variables are taken into consideration when engineering ammunition.

Jason


#10

APFSDS

Not sure how early your M865 is. The originals didnot contain propellant containment bags. I did the first ammunition robustness test of the 120, CCC rounds in an early M1E1 tank. Busted a number of rounds, thus the containment bag. I havent built any in a number of years but if I remember correctly the propellant is loaded into the M865 thru the primer hole with the round inverted and shaken. The primer was then inserted. It used to be inserted by hand. The factory may still do it that way. After an accident inserting a primer into a 105 tank round we were required to design and build an air powered remotely operated insertion tool. The M830/831 rounds had the projectile assembled to the case cap. The stick propellant was assembled around the projectile boom and the whole thing slide into the case. The primer was all ready installed in the case. The case cap to case joint is called the skive joint and has opposite tappers. The case cap and case are glued together at that joint.

Rookie


#11

Wow! Very nice meeting you, Rookie and even nicer to learn from your first hand experience. Thank you very much for that explanation. I did not realize that the powder was filled threw the primer hole. That answers a lot of my questions because for the life of I could not understand how every nook and cranny was filled with powder on the APFSDS rounds. I have been starring at the M831 sectioned round for hours and it looks like the stick propellent is in 4 individual bags shaped perfectly so they fit between the boom and fin assembly fins. I would have loved to watch the factory produce these from begining to end. I thank you for all that you did to insure our Tankers had the best and safest ammunition.

Jason


#12

Thank you and I am sure we will be conversing.

Emory


#13

Thanks a lot Rookie! This is the best information we can get and sure a lot more then I expected. A good answer to my question.