Evolution Of The US 120MM TPCSDS-T Projectile


#1

I have been thinking about writing a short IAA Journal article on the evolutionary development stages of the US 120MM M865 TPCSDS-T (Target Practice Cone Stabilized Discarding Sabot Tracer) projectile and figured I would start a forum thread first to possibly gain more information and insight. I am hoping to learn more information on the US/German relationship on its development as well as anything else IAA members may be able to contribute.

When the US Military switched from the 105MM M1 Abrams Tank to the 120MM M1A1 Abrams Tank they had to hustle to create quality 120MM ammunition with CCC “Combustible Consumable” cases. At the time, 120MM CCC tank ammunition was at its infancy and the military fast tracked the development of the M866 TPFSDS-T (Target Practice Fin Stabilized Discarding Sabot Tracer) and the XM827 tactical APFSDS-T (Armor Piercing Fin Stabilized Discarding Sabot Tracer) rounds. Both the M866 and XM827 were developed solely as interim rounds while development of the M865 TPCSDS-T was being done.

My Thinking On The Order Of Development (Left To Right - Oldest to Newest)

Not Sure Of Date
GERMAN DM38 TPCSDS-T

  • Fits OVER CCC Case
  • Ported Cone Stabilizer

Circa 1982

  • M866 TPFSDS-T Projectile Next To The XM827 APFSDS-T
  • “Note The Unusual Shoulder Shape Of The Sub-Projectile Darts”
  • Both Projectiles Fit OVER The CCC Case
  • Both Projectiles Incorporate The Same “Long” Sabot" Design As The German DM38 TPCSDS-T

M866 Projectile

Cira - 1987
US M865 TPCSDS-T

  • Long Sabot
  • Ported Cone Stabilizer
  • Fits OVER CCC Case

Cira - 1989
US M865 TPCSDS-T

  • Snaps “INTO” the CCC Case
  • Fluted Cone Stabilizer

To my knowledge, this projectile design was experimental and never adapted. It has the longest, wasp waist, sabot of any M865 that I have seen. This fits in the development timeline between the issued “long” sabot and the next adapted M865 with a short compressed sabot.

Cira - 1999
US M865 TPCSDS-T

  • Short Sabot
  • Dark Blue Sabot
  • Snaps "INTO The CCC Case
  • Fluted Cone Stabilizer

Cira - 2002
US M865 TPCSDS-T

  • Short Sabot
  • Light Blue Sabot
  • Snaps “INTO” The CCC Case
  • Fluted Cone Stabilizer

To my knowledge, this is the final and currently developed variant of the M865 TPCSDS-T round? I was told by a retired tank ammunition tester that the color of the sabot petals and its change from the 1999 dark blue was an important design feature. He told me that the earlier dark blue somehow caused barrel wear issues. I am going to try contacting him for a more detailed explanation.

Side By Side Comparison Between Cone Stabilizers (Ported & Fluted)

Example Showing How The Older M865’s Fit “OVER” The CCC Cases.


#2

I know very little about this (seems to be a common theme for me) so I did a quick search on DTIC (Defense Technical Information Center) and came up with a few items that may provide some info (assuming you haven’t already seen these):

120-mm Target Practice Cone Stabilized Discarding Sabot with Tracer (TPCSDS-T) M865 (E3) Rework Report (Pop-Rivet Design): dtic.mil/dtic/tr/fulltext/u2/a411174.pdf

Firing US 120mm Tank Ammunition in the Leopard 2 Main Battle Tank: dtic.mil/ndia/2008gun_missile/6526Huls.pdf

PAP8386 (propellant) for Tank Training Rounds: dtic.mil/ndia/2007im_em/BBri … NG2007.pdf

120 mm M865 TPCSDS-T by ATK: atk.com/products-services/m8 … -120-mm-2/

I look forward to your article in the IAA Journal and I hope others with knowledge on this subject will chime in and help out with this important endeavor!

You’re off to a great start by the looks of the photos you’ve posted here.

Brian


#3

Jason, I don’t collect this stuff, but that doesn’t mean it isn’t interesting, PLEASE do get an article together for Chris to print. This stuff is amazing.


#4

Brian, thank you for the additional M865 links. Some I was familiar with but some were new to me, especially the pop rivet case adaptation and the way they did pendulum test to study there ruggedness. Over the years, 120MM CCC case design has changed a lot, primarily concerning M865 variants. I think for my Journal piece, I am going to focus mainly on the projectile changes and to a minor extent on the US/German collaboration. I think Germany designed the first M865 designated DM38 in Germany and shared initial design parameters with the US, but not 100% sure of the entire story. I heard that it may have been a German idea but funded by the US? I would love to learn the true relationship. In any case, the M865 TPCSDS-T round has changed drastically from its first initial design.

Pete, thanks for the kind words of encouragement! I am going to work on it. I am getting ready to tear my house down to build a new one and am going crazy moving stuff into a rented warehouse. I will be living in a tiny camper during construction so I can be here with all the animals. I am going to work on gathering some more info to hopefully start writing soon. May be a short piece with lots of pics. :-)

If anyone has info on the US/German connection to this round, I’d be super interested.

Jason


#5

Keep in mind that the U.S. Army originally was happy with the 105 mm for the M1 and the 120 mm was considered overkill. The notion that the U.S. financed the development of the DM38 or that the M865 preceded the DM38 seems unbelievable to me. Frankly, to German ears it sounds like the Americans really designed the MG42 and the Germans later copied it.

The maximum range of the 120 mm war round is about 120 km (although the required elevation is above what the Leopard 2 can reach). Germany had every reason to develop a much shorter range training round. The idea of the DM38 is that at very high speeds air can flow through the holes in the cone, allowing a similar trajectory to the war round. Below a certain supersonic velocity, a choking effect practically closes the holes to the air flow, significantly increasing air drag. (I am not convinced that this is a concept of real practical value. But this is how its working was described.)


#6

As you say, the projectile is a Rheinmetall development. For reference check US Pat. 4,362,107 (Dec 1982).


#7

At 10 degrees elevation, the original DM13 APFSDS had a range of a little over 28 km while the DM38 range was 6.5 km.


#8

Definitely, a Rheinmetall development! That being said, there is a US/Rheinmetall relationship concerning the M865, especially in its early stages of development and it has advanced over the years considerably from the DM38 variant style.

With modern tank armor and the distances that current tanks engage their targets, the 105’s do not compare to 120’s. In addition, the Rheinmetall smooth bore M256 120MM gun system used on the Leopard and M1A1 is so much better for firing APFSDS ammunition then the rifled 105MM M68 gun utilized on the M1 Abrams. Because APFSDS ammunition is fin stabilized it does not require the rifled barrels so all the APFSDS projectiles need to be fitted with slip ring driving bands.

J
PS:Thanks for e-mailing me the great links Brian!

Alex, how do I find that patent?I never looked up patents before.


#9

I assume you mean bdgreen. He listed the links in his post.


#10

Woops! Your right!! THANKS Brian, BDGREEN!!!

J


#11

Alex,

I got the patent! Just googled the number you gave me and it came up.THANK YOU! I printed it out to read tonight. Looks to contain some great early info that I was hoping for.

Jason