US 105mm M900 APFSDS-T SLUG - Testing Case Question

I recently added this beautiful, 100% INERT, US 105mm, M900 APFSDS-T Testing Slug, to my collection. I normally don’t target (Pun Intended) inert SLUG projectiles, but the, M900 is the only US Type Classified and adopted for US Service,105mm APFSDS-T round not represented in my collection. Missing that one so I was thrilled to add this testing round.

It came with an unfired, unprimed, Steel M150B1 case. The tactical, M900 uses M148A1B1 steel case and a modified (shortened) ELEC M120 primer. My question is, during the R&D stages where I am guessing this SLUG would be used, would they use a tactical M148A1B1 case or could they substitute other cases with the same pattern, for the M68 Gun? I have noticed that most, US, APDS and TPDS 105mm projectiles are crimped to M1501B1cases and most APFSDS rounds utilize the M148A1B1 cases. The only difference I can notice is that the M150B1 case is about 1/4" taller.

I would like to eventually section a window out of an empty case, but want to make sure that it is an accurate match.

Thanks big time for any help :-)


Jason

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who knows why I have accumulated a 105mm & a 120mm

PS… I’m clueless" other than they are somewhat special purpose (and make great door stops !!!)

likely destined for South Florida one day

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WOW!

Both of those are pretty epic! I am pretty sure the 105mm FP SLUG is for a US made APFSDS projectile for, Canada. Looks almost identical to our adopted M735 just with slightly shorter sabot assembly. The other one, is historic with its connection to the M829, the US’s first adopted 120mm APFSDS with a DU core. First used in Iraq, fired from our new M1A1 upgraded tanks.

Also, concerning these testing slugs, I recently read that they were for testing pressures to see if the cases could handle things. I always assumed they were part of the R&D connected to the tactical projectiles design in some way. Pretty cool.

My only other tank slug used to live in, WI, a sweet 105mm :-) Totally awesome.

Jason
PS: Thank you for this photo! Saving it!
PSS: Totally Special Purpose Door Stoppers :-)

Jason, usually these projectiles are not related to the projectile development as such. Means they usually represent a physical “dummy” for inner ballistics and barrel wear.

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Thanks so much, Alex! This makes a lot of sense. I sent a e-mail to a friend who used to work at one of the big US tank ammunition manufactures and he wrote back saying, “The slugs are used for case testing and any tests that normally only require pressures or action times as data points.” So clearly not a part of the projectiles RD.

Always amazed at all of the science and testing that goes into ammunition of all bore sizes.

Jason

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Jason and Pepper, great pictures, thanks for sharing!

Slug loads are also about $1,000-1,400 cheaper than regular APFSDS-T loads. For example, in 1978 the estimated cost of an XM829 was $2,250, while the slug variant costed “only” $1,125.

Regards,

Fede

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There are two types of slugs. Cannon proof and super slugs. Cannon proofs are used to test new gun tubes to confirm the production process. Super slugs are used to proof the gun mount. They provide the equivalent of the highest pressure producing round in the inventory tempertured to 120deg F. Super slugs mainly test the trunnion forces, breech forces, and recoil travel specs. After proofing there is a complete tear down and visual, measure spec and magnetic particle inspection of critical parts.

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What tyoe of slugs do I have pictured? An ignorant guess would be a “big one” (? super). And a “little guy”

Again. I’m clueless

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Out of interest, here is a 105mm one I believe for the M774?

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BRILLIANT variable, Fede! I never considered price point. I am sure that is a big factor and makes lots of sense!

Jason

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More amazing information! Thank you! I had no idea!

Now I may have to really start hunting down, Tank Ammunition testing Slugs for the collection :-) Always amazed by the amount of science and testing and degree of brainiacs that goes into the creation of a new type classified round, weather 9mm or 120mm + . Brilliant Minds!

Jason

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I’m also guessing, SUPER :-) Not 100%

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That’s the same 105 I have. I was also told, M774 :-)

J

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Hi Pepper,

If the 120mm has a flat forward end it is a cannon proof slug . Have no idea how one of those got away. If I remember correctly we received the slugs and built the rounds. The m900 I don’t think is a proof slug. I was not involved in the development of the m900 but if that is what I think it is I am rather sure it was classified and may still be. There is only two Army testing grounds that it could have come from or it came from the round developer. It may be a briefing dummy , ie. the weight and length are not correct or it could be an unfired projectile which was lifted from a Proving Ground or the developer.

Take care

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Thanks, Rookie for the additional, amazing, information. So much to learn about these specimens.

I highly doubt that the M900 APFSDS is still classified. I have every stat on it and it is freely published online, in JANES and even in corporate flyer handouts. It was barely, if ever used by the US as it came out when we upgraded our MBT’s from the 105mm M1 Abrams to the 120mm M1A1 Abrams.

I think it may have been briefly continued to be manufactured for foreign sales, but I am 99.9% sure it is no longer? As far as the M900 SLUG goes, I have seen at least 4 others in other collections and come up for sale in the past. One was from a junk yard of all places a few years ago.

Jason

Hi Jason. I believe that M900 is a charge establishment slug used during R&D phase not a proofing slug. Take care

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EXCELENT! Thanks again, So Much!

I have learned of two new terms from you;

  1. BRIEFING DUMMY
  2. CHARGE ESTABLISHMENT SLUG

Really super grateful for all of your help and insight into this. Can’t beat it!

Jason

The USMC used the M1/105 for a number of years before buying the M1A1/120.

Very true!

Pretty sure the, MARINES, were the last to touch the, M900. I am not sure how many, M900’s where ever fired in anger though? Very low production rate was authorized in 1989, but never received full standardization approval, according to, JANE’S.

I was always under the, “Assumption,” that most of, Saddam’s tanks were taken out by the 120mm M829 and M829A1 Silver Bullet, APFSDS-T rounds?

Jason

The M900, was also highly pressured compared to it predecessors the, M735, M774 and M833. Due to this, only certain M1 Abrams fitted with a modified M68 Gun could fire the round safely. I do have a fired M900 case that has a detailed stenciling on the side stating that it can only be fired from, M68 Tank Guns with a serial # higher then ################.

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No doubt the 120 did its share, but my impression at the time was that many more were taken out by the GAU-8.

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