Question regarding the Firefly

[Imad]

Hello

I am reading a book in which the author makes a negative comment about the accuracy of the 17 pounder on the Firefly version of the M4 Sherman. The gun was undoubtedly powerful but apparently the accuracy was questionable in long range firing. Does anyone have any input on this? Thanks in advance.

[C.GILLONO]

Hi
I read the APDS shot was initially not accurate (interfernce between the separating sabot elements and the muzzle brake), but nothing on the normal AT shell
HTH

[Die Blechtrommel]

In series: Stupid questions

I read the APDS shot was initially not accurate (interfernce between the separating sabot elements and the muzzle brake), but nothing on the normal AT shell

What APDS stands for? Armor Piercing... and sabot elements?
Greets
Johnny B. Simple

[C.GILLONO]

Armour Piercing Discarding Sabot

[C.GILLONO]

This type of shot was multipart: a smaller shot (not the full size diameter of the bore) of harder metal and lighter elements to reach the full bore diameter - the elements peeled off after the muzzle brake and the lighter shot gained velocity to have higher penetration against the target's armour

[Die Blechtrommel]

Thanks!

I just recently found out the reason, why Firefly had no hull MG.
The reason is simple: 17 pounders took so much more room that the radio-operator with the gun and chair was removed to make extra room for the shells. Radios were reinstalled into the "Rommelkiste" that is the steel box at the back of the turret and were operated by the tank commander.
With best
Juha

[Die Blechtrommel]

a smaller shot (not the full size diameter of the bore) of harder metal

Could that be tungsten-metal (don't remember the other name of it)? The Germans fell short of it.
With best
Juha

[ducatim901]

Wolfrahm.
JK.

[PaulJ]

Don't have any stats to offer on Firefly accuracy per se, but in a related angle -- I do know that they had issues with smoke and dust raised by the concussion of firing obscuring observation of the target after firing. This made it difficult to impossible to adjust fire, which [indirectly] has the effect of reducing the accuracy of fire overall. The Brit/CW armies used to get around this by having another tank in the troop observe and report the fire.

Cheers,

[redcoat]

Don't have any stats to offer on Firefly accuracy per se,

The 17 pdr was very accurate with rounds other than the early APDS shot

but in a related angle -- I do know that they had issues with smoke and dust raised by the concussion of firing obscuring observation of the target after firing. This made it difficult to impossible to adjust fire, which [indirectly] has the effect of reducing the accuracy of fire overall.

This was a problem faced by all late-war high velocity guns, the German 75mm/L70, and the 88mm/L70 all suffered from the same problem

[Die Blechtrommel]

Interesting, but true. The smoke and dust problem continued well after WW II.
How is it now? Russian laser blinds the gunner for a few seconds (T-72, at least).

But back to the Firefly.
Was it true it had two Cadillac aeroplane-engines, (modified, of course)?
BTW, thanks for the answers!

Greets
Juha

[von Salza]

Hi,

No doubt the 17pdr was a powerful weapon and could cope with anything the Germans had to offer in Normandy (Panther or Tiger) when used with the APDS round, however these were not available in June 1944 and only in the latter stages of the campaign (late July) did they see use in sufficient quantities. It was advised that even if the APDS round was available that they should really only be used against very heavily armoured targets, as although it was superior in armour penetration capability, it did less damage compared to the standard AP round.

The 17 pdr was accurate at all standard battle ranges but there was a question mark about the accuracy at ranges over 1000yds. There are many reasons for this, but it was generally thought that the combination of poor optical equipment in the Sherman not suited to long range firing, excessive muzzle flash/dust, cramped turret and inexperience of the crews were all contributing factors. It was assumed that in theory the 17pdr was more than capable of long range firing and if a hit could be secured at these ranges it could defeat any German armour then in use (with APDS round). However it was noted that the APDS was generally less accurate than the standard AP round at ranges over 1000 metres. The main draw back of the gun was the lack of a useful HE round.

There was indeed some concern early on about possible damage to the gun when firing APDS, shortening it's barrel life and possible damage to the muzzle brake.

Could that be tungsten-metal (don't remember the other name of it)? The Germans fell short of it.

Yes the APDS round (British Invention, I thank you) had a narrow Tungsten core surrounded by light duralumin collars of the bore diameter. These were designed with weak spots that would break in the gun after firing and were then discarded through centrifugal force after leaving the muzzle.


Hope this helps

Regards

David

[Die Blechtrommel]

Thanks, David!
Enyone knows 'bout the engines?
Juha

[von Salza]

Hi,

The 'Firefly' was the British name used to refer to 17pdr armed M4 Sherman medium tanks and as such the engines used in each of the 'Fireflies' would therefore depend on which version of the M4 that was rearmed.

The British & CW armies rearmed the following versions of the M4 with 17pdrs;

M4A1 became the Sherman IIC
M4A3 became the Sherman IVC
M4A4 became the Sherman VC

The engines used in each variant would therefore have been;

M4A1 - Continental R-975 (based on the Whirlwind aero engine) generating 353HP
M4A3 - Ford GAA V8 Gasoline engine (developed from a design for an aero engine) generating 500HP
M4A4 - Chrysler WC Multibank engine (made from 5 commercial car engines on a common drive shaft) generating 370HP

The M4A3 was the main M4 variant chosen for use by the US army and most were retained for American use. The M4A4 (Sherman VC) was the variant that saw the most 17pdr conversions.

Interestingly enough you mentioned that the Firefly conversions all had the Bow MG deleted, but it has to be noted that this was not the case with the 76mm M1A1 & M1A2 gun armed US versions of the M4 who all retained the Bow MG. Also the 76mm armed M4 versions carried 71 rounds of main gun ammunition but the 17pdr could only muster 42.

Hope this helps

Regards

David

[Die Blechtrommel]

Thanks von Salza for a thorough answer!
Juha