British 17pdr and 32pdr A/T guns

The 32-pdr was based on the 3.7" AA gun, was the 17-pdr based on an existing gun or was a clean sheet used?

 

Clean sheet AFAIK. There certainly wasn't any other British gun which used the same ammo (or anything like it).

Tony Williams: Military gun and ammunition website and discussion
forum

 

Just while the 17pdr is being raised; it has been mentioned several times that the 17pdr didn't have a very good HE round was there a particular reason for this?

 

Yes, it was primarily designed for the Anti-tank role, not infantry support-role.

kbo

 

Yes but why does this result in a less effective HE round?

 

Because they wanted a gun wich could fire very effective AP rounds, not HE rounds. The 17pdr's HE round wasnt all that bad either, I would even dare to say that it was atleast as effective as the normal German 75mm HE round.

KBO

 

The problem was that they at first designed the HE round to be fired at the same muzzle velocity as the AP, in order to keep the trajectory the same. The trouble was that the high pressures to reach the velocity required a strong, thick-walled shell which limited the HE capacity. Later on, they downloaded the HE shell to a lower velocity and were able to use a higher-capacity shell.

The US Army suffered a similar problem, in that the HE shells for their high-velocity 76mm tank gun were less effective than those for the lower-velocity 75mm.

Tony Williams: Military gun and ammunition website and discussion
forum

 

So basically you could choose between a HE round that was a bit limp wristed when it got there, or you could have one with less propellant that was more difficult to shoot straight with.

 

But does that mean that by the end of the war the Firefly as well as the late Sherman were firing much improved HE rounds, so that this is another temporary flaw that got stuck in collective memory?

 

I'd guess they also wanted that HE shell to weight nearly as much as AP, otherwise it would have much worse sectional density and therefore different trajectory despite similar muzzle velocity.

Which brings me to an other question: Apparently german Minengeschoss -shells used in aircraftguns were strong enough to stand high pressures. Were this kind of shells used only in aircraftguns or did some larger calibre guns use them too? Surely larger calibre shells had their burster chamber made more efficiently than just drilling a hole to shell and filling it with explosives?

 

Might depend on the nature of the burster. Some explosives were more resistant to shocks than others.

 

Given that for the AA role, DP secondary guns or RN and USN ships would require a high velocity (I assume) ,did the DP guns on RN and USN suffer this problem as well?

 

I don't know because I don't have enough information on HE filling pecentages for the big naval guns. However, the rule holds generally true that the higer the velocity you want to launch a shell, the lower the percentage HE is likely to be (other things being equal).

Tony Williams: Military gun and ammunition website and discussion
forum

 

Wasn't the 17 pr derived/ developed from the Vickers(?) High-velocity 75mm? Which didn't get anywhere AFAIK, and was, I believe was a follow-on design from the 10/12 pr (I've seen both designations) 75(?)mm.

 

re hv 75mm

No the 17 pounder was manufactured prior to the hv 75mm.
it was infact the shortend "77mm" which was effectivly a shorter 17 pounder, that resulted after the hv 75mm project.