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Armour Piercing Discarding Sabot

by Julian Shales - WW2 Site Helper

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Archive List > Weaponry and Equipment

Contributed by 
Julian Shales - WW2 Site Helper
People in story: 
Tank and Anti-Tank Gun Crews
Location of story: 
Normandy and North West Europe
Background to story: 
Army
Article ID: 
A2187506
Contributed on: 
09 January 2004

A new radically different ammunition was given to the crews of Churchill tanks, Sherman Fireflies and Infantry and Royal Artillery Anti-tank units.

Unlike any previous anti-tank ammuntion this type comprised of 1) the Sabot, a light metal "holder" with of same diameter as the gun calibre, and 2) the much smaller diameter tungsten Armour Piercing round held within the Sabot. On being fired the air resistance on the Sabot detached it from the Armour Piercing round which then travelled on to the target.

Strangely, only two calibres of APDS were ever issued, 57mm for the 6 Pounder and 76.2mm for the 17 Pounder. However, the most numerous main gun in most British, Canadian or Polish tanks was 75mm, and the crews of these lacked any reliable way of knocking out the German Panther (except for the side and rear if close and lucky) or the Tiger Mk 1 and Tiger Mk2 because their armour was of significantly better quality and design. APDS was not isssued to American units which were in a worse situation because their new 76mm gun had a very dissappointing performance compared to the 17 Pounder.

APDS was introduced in June 1944 for 6 Pounder 57mm guns and had a significantly higher penetration performance over any previous types of AP ammunition, in fact its performance was about twice as good/deep (140mm compared to 84mm at 500 yards) although it lost accuracy over long ranges (1000 yards plus) because of slight variations in the way that each Sabot detached from the Armour Piercing round about 100 yards after leaving the muzzle of the gun barrel.

The earliest account for 17 Pounder (76.2mm) APDS that I have found seems to be in October 1944 and possibly not for the Firefly but only for Royal Artillery Anti-Tank Regiments.

I also understand that just before Normandy Churchill tanks with 6 Pounder Guns were converted to the new British 75mm Ordnance Quick Firing gun and thus were unable to make use of APDS's potentially firefight winning properties. However, some Churchill units may have retained or converted back some of their tanks to 6 Pounders to specifically use this ammunition.

The infantry were luckier in that they kept their 6 Pounder Anti-tank guns and by mid June 1944 I understand that they may have recieved some APDS rounds to use.

Today's tank crews make use of an updated version of this round, APDSFS, the FS stands for Fin Stabilised.

Can any veterans recall their use of APDS?

Julian Shales

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Message 1 - APDS

Posted on: 18 May 2005 by Weaponcharles

I am Charles Markuss, a British 'guns and armour' nut and wargamer / researcher involved in the Advance Squad Leader board wargames produced in the USA.

The first field trials with 17 pdr APDS took place in Normandy in August 1944 when US and British army personnel watched a demonstration against captured German Panthers.

The early batches were regarded as sub-standard, and the performance was very erratic - the round was very inaccurate compared to 'standard' APCBC, and much less accurate than the APCR round used in the US 76mm gun. The US did at one stage consider fitting APCR projectiles into the 17pdr shell cases they envisaged being available when Sherman Fireflies were to be (eventually) issued to US army units because the APCR round was more accurate than APDS. Only one US unit, in Italy, ever got (12) Fireflies and too late to use in action.

APDS is hazardous to friendly personnel in front of the gun muzzle because the sabot pieces and base-plate can travel to about 250 yards (sabot pieces) and 600 yards (baseplate) with about 6 degrees of dispersion, in the case of the 17 pdr, according to documents that I examined in Bovington last month. For the post-war 84mm 20 pdr the distance was far greater - out to about 1500 yards.

17 pdr APDS first became available in small quantities in September 1944 and always remained far less accurate than APCBC; troops were urged to conserve supplies and a vehicle might have between 5 and 10 rounds available in ideal circumstances - this from verterans' recollections. Anti-tank units would have had priority in supplies over tanks, but scrounging and barter probably took place. The US 76mm APCR was also first used in September 1944 but was far less effective at penetration.

It is clear from the RAC half-yearly progress reports kept at the Bovington Tank Museum that crews often 'wasted' APDS against targets that APCBC could have destroyed. The performance against the Panther's front plate was still marginal, even with APDS, because of the sloped plate's deflective qualities. Also bear in mind that most Allied AP rounds were inert, whereas 'standard' German and Soviet rounds had small explosive bursting charges to detonate after penetration and set the target vehicle's own ammunition alight (fuel fires rarely caused vehicles to burn in comparison)

6pdr APDS was available from June 1944 and the US forces also received it for their 57mm anti-tank gun, firing slightly over 11,000 rounds by VE Day whereas US forced in Italy fired only a few hundred rounds (probably due to the lessened trhreat of enemy armour in that theatre). I do not have the exact figures to hand but can give you them if you wish.

The most effdective western Allied AP round was the 90mm APCR round, but this was not available until March 1945.

 

Message 2 - APDS

Posted on: 17 July 2005 by jdbukis

the apds round after being sorted out so to speak was, acording to official documents i have seen referenced in, to be able to penetrate the glacias up to 700 yards with a single hit, probably by 50% of firings maybe not. it was first issued from what i have found in august 44 for 17pdrs and june 6th for 6 pounders. however i have been led to believe from another source the british had a apcr shell of there own issued from october 1943, if my memory serves me it was cancelled in september 44. apcbc from the 17pdr was capable but not dependable on to penetrate the glacias of the panther although, it was said to have been a much safer shot against the nose plate or the turret. apcr figures i have is 109mm at 500 yards witha 30 degree angle of impact for 6 pdr and 155mm for the 17pdr at the same. in tests of the us m1 57mm nose plate was penetrated at close range and so was turret with apcbc at 300 yards 2 degree angle of attack. just some random info i know. of course how figures relate to there real life performence is another issue

 

Message 3 - APDS

Posted on: 17 July 2005 by jdbukis

also i was read in one source. i will try to find it that the hvap for the us 90mm was experimental/ at the best incredibly rare.

 

Message 4 - APDS

Posted on: 14 October 2005 by Weaponcharles

US 90 mm APCR, according to copies of US army documents in my possession, was issued in March 1945 and was very rare. Some (secondary) sources state that it was available from about January 1945, and this is the date that was - erroneously - used in the Advance Squad Leader wargame. If the issue of 76mm APCR was anything to go by, crews were lucky to get two rounds each and tank crews especially were lower priority that tank destroyer crews and so had to 'scrounge' or barter to get any.

The 90 mm APCR rounds at the time had a 'T' prefix to indicate that they were non-standardised (whereupon an 'M' prefix was allocated) but the only real 'experimental APCR round in 90 mm calibre was that fired by the solitary 'Super-Pershing' fitter with the experimental T15E1 (?) gun, which used two-piece ammuntion and apparently only ever fired its gun once to destroy a German tank late in the war.

 

Message 5 - APDS

Posted on: 14 October 2005 by Weaponcharles

The only British gun to use an APCR round was the 6 pounder, which had it for a short time before APDS was perfected. There are some vague references to a 'new' type of AP shot in some rgimental reports cited in secondary sources, but only David Fletcher's Mr Churchill's Tank, Schiffer, Atglen PA 2001 (?) actually refers to it, as HVAP. It was issues to some Churchill units at least in Tunisia, and North Irish Horse for one had it. It was found to be "ballistically unstable".

The 109mm penetration for the 17 pdr at 500 yards is for uncapped AP shot from the sources I have; to the best of my knowledge APCR was never produced for this gun, though you never know. Panther's glacis was hard to penetrate for any round, due to the acute slope and the trials at Isigny in August 1944 showed that even APDS was marginal in performance. The best type of shot against sloped armour is a projectile with a bluntish nose, APCR and APDS, while having the velocity to often penetrate, tend to bounce off easier than blunt shot would. Blunt shot, of course, often cannot reach the velocity needed to penetrate. Hitting with APDS was the problem, as the round was terribly inaccurate (the 6pdr APDS tended to hit about 2 feet higher than the aiming point, for example) and figures showing this poor accuracy for 17 pdr APDS can be found in Mark Hayward's Sherman Firefly, Barbarossa Books, Tiptree, Essex c. 2001. Your issue dates are spot on, and the nose plate was more vulnerable to attack as the slope towards the projectile assisted penetration and the armour was thinner - 60-65 mm compared to 80-85 mm (batches varied) on the glacis. If you ever get to the Polish army museum in Warsaw, there is a Panther nose plate on exhibition outside with various 85mm rounds stuck in it, but from memory few penetrations. The panther turret was not that hard to pierce - 100-110 mm mostly near-vertical armour, the mantlet 100 mm curved but likely to deflect rounds up if the hit was above dead-centre, or down through the hull roof if hitting below the centre-line.

 

Message 6 - APDS

Posted on: 18 October 2005 by Weaponcharles

Correction! Not North Irish Horse (I did some checking!) but 51st RTR, who certainly had it at the 'Steamroiller Farm' action in Tunisia. According to David Fletcher's book, page 109, this unit had 20 rounds of 6 pdr HE (not very effective compared to 75mm HE in Grants, Lees and Shermans) and 4 rounds of 6pdr APCR per Churchill tank by about 13th April 1943.

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