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17 pdr gun sight

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hi fella's

just thought i'd post some pics of a 17 pdr gun sight it's a no.41 mk2s,there's something that i was hoping someone could clear up for me.Why does it just have a cross hair and no range markings ,i have the sight for a firefly which has the range markings upto 3600 yds and it's the same gun, seems strange to me but if anyone could enlighten me i'd be grateful.







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found on another site re-laying of the 17 pounder using the a/t sight


Until the beginning of 1942 British anti-tank gunnery used a 'false range', they aimed low and added a few hundred yards depending on the actual range. From the beginning of 1942 they adopted zeroing of anti-tank guns, usually using a tank sized target at 500 yard with the aim point being centre of mass. This meant the actual range could be set on the range drum, part of the drill for coming into action was to prepare a range card for recognisable objects in the zone of fire. They also issued simple tables for lead depending on range and speed and whether the target was a 'direct crosser' (45 - 90 degree approach angle) or 'diagonal crosser' (15 - 45 degrees). This was related the lead graticules ('lead units') in the anti-tank telescopes. Of course the time of flight of the shot from high velocity anti-tank guns at normal battle ranges was under 1 second, and a tank moving at about 15 mph covered about 7 yards in this time. A 'direct crosser' at 15 mph required a lead of 1 and a 'diagonal crosser' a half, the smallest lead order was a quarter.


Figure 2 - Anti-tank Sight Aiming - Graticule Method

The angles subtended by the graticules both vertically and horizontally were all part of the layer's knowledge







In early 1943 'central laying' was approved as an alternative to graticule laying. This meant that the layer set the lead on the lead drum and aligned his centre graticules with the target. In either case the layer tracked slightly ahead of any crossing target and then let the target move onto his graticule aimpoint when the gun was loaded and he as ready to fire.

Anti-tank engagements were conducted by the No 1 giving initial orders to identify the target relative to the centre of arc, describing it, ordering the range and lead, and ordering fire. He then ordered corrections using 'Add' or 'Drop' for range (these were cumulative) and a new lead (not cumulative). These corrections were judged by observing the tracer to see where the shot went relative to its target. By 1943 ranges and corrections were always ordered to the nearest 200 yards unless the target was hull down in which case 100 yards was used.

The following table, based on firing table probable errors, shows the inherent direct fire accuracy of anti-tank guns when their MPI was on the target centre (ie no human errors). In operations worn guns and other mis-alignments could reduce the chance by up to half at shorter ranges and to a quarter at longer ranges. In the first years of the war training material was issued detailing the most vulnerable areas of enemy tanks. This may have had some use for very short range engagements with infantry anti-tank weapons. It was unrealistic at longer ranges and the 1942 doctrine of 'centre of mass' ended it as far as anti-tank artillery was concerned. Trials also established that a 2 or 6-pdr at the end of its barrel wear life would hit only 18 inches low at 1000 yards.

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hi steve

each tank has a specific sight or more accurately not the tank but the turret main gun and mg combination.so the firefly shown has graticules for the 17pdr plus .30 mg so can only be sherman but i also have a sight for a 2pdr with besa so could be used on several tanks ,incidentally all the sights are the same size and shape pretty much.

it,s interesting that you mentioned a spg as i have the sight for an early 6pdr a/t gun which can also be used on the 25pdr so maybe your right it could possibly be used on the sexton i would assume, but as you know i'm no expert.



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Hi all,

Yes, the first assumption is correct. The 17pdr sight for the firefly was a specialized reticule as the tank telescope version required both coax MG and main cannon ranging scales. As the tank version of the gun was mobile and ranging and had to keep a constant "eye" on both stationary and mobile targets, that were constantly changing in distance due to both the movement of both target and tank a highly adjustable sight range was needed. In the Firefly, as you probably already know, the horizontal line moves vertically against the fixed scale as does the vertical line moves horizontally for deflection. As I have read, tank gunners of the period were not very fond of the left and right deflection behaviour of the graticule and normally left it fixed.

But the telescope graticule that eddy posted above is a No. 43 x 3 L Mk. I for the Mark IV and VII gun and .30 mg. and the corssair does not move, it is fixed. The difference here being that the markings of height below the central mark provides for the height destinations and the distance markings laid on the target as called for and the gunner would read across the numerical scale to verify. This one went to Sherman C tanks.


The main point is that the tank gunner needed to keep his eyes on the threats and could adjust the range while on the move without having to take his eyes from the telescope to look away to the range drum and back. The A/T version, already having the range drum mechanism, normally was only needed at the moment(s) of final direct fire, as the estimated distance had already been calculated and input to the carriage.


Not only that, but the No. 43 x3 ML Mk 3 for the Mark II/30 cal MG (Challenger tank) and Mark IV and VII/30 cal MG (Sherman) were more complex and delicate instruments that had revolving rings that controlled the moving graticules and needed special care. Also the differing contractors made different installation brackets for the interior of the turrets and were not always interchangeable. Also the No. 43's and 57s (as also the other Mk gun telescopes for tanks) had a light path that required a definitive length for the prisms and mirroring configuration and so the accuracy of image reflection required a specific length of the telescope itself for the necessary glass partitions, which if you were to try to install it in an A/T carriage the length would make it impractical.




Sorry to be convoluted, but everyone above is right, a different telescope for each application.:angel: You have to look at what the capabilities of range are for the particular gun first, then the optic was designed. You wouldn't get a telescope that was ranged for 3600 meters if the gun itself could only send a round downfield 1200 m ;).

Edited by mlespaul
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