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After Dunkirk due to the scarcity of AT guns it was decided to produce the 2pdr as not to loose time to retool for the 6 pdr.

 

How long did it in reality take to retool from the 2 pdr to the 6 pdr ?

 

Did the fact that all tanks in production or in the pipeline were designed for the 2 pdr also play a role ?

 

Is there a scenario feasible where for the first emergency the 2pdr was built as quickly as possible, and when enough (sufficient but not in overwhelming numbers) were available to swith to the 6 pdr as fast as possble ?

 

Thanks,

 

Inhapi

 

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Small unit production is easy. Large unit factory production with machines set up to perform multiple boring operations on plates and other tasks simultaneously are very complex. I suspect that a 6 month lag time where the factory is doing nothing but retooling is a big issue.

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I can't help but wonder if rather than re-tool for the 6 pounder, they could have set up additional factories with the tooling to make them whilst continuing to build the 2 pounder in the existing factories. Remember, this was at a time when we were building or converting lots of additional factories to make all sorts of war materiel. The fact that it wasn't done leads me to believe it was somehow impractical - I suspect lack of skilled workers may well have been the bottleneck.

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The fact that it wasn't done leads me to believe it was somehow impractical

 

 

My thought too. Usually things are done for reasosn that were good or were considered good at the time. Though my suspicion is that converting a civillian plant to produce a not that small high velocity gun wasn't something you could do with many plants. Probably the top of the line ones but they were probably busy with other and more important stuff.

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This site gives these figures for the 6 pdr (i think)

 

Canadian production began in October 1941, with barrels being made in Longueil, Quebec and carriages in Regina, Saskatchewan. More than 8,000 guns were produced in Canada during the war, along with almost 7 million rounds of ammunition. This gun was made in Canada.

 

 

http://en.rcamuseum.com/artillery-collection/test-4

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Actually the 2pdr might have been the 3rd most powerful AT at the time, behind the French 47/60(?) and that ridiculous Russian 57mm.

In theory, in practice 2pdr could not penetrate 50mm StuG IIIe front armor, while US 37mm could at short range.

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Thank you for sharing this! It is a long read, I have not had the time to go through all of it yet, but a very interesting one. Shows very well just how difficult the supply situation was for everybody, Allies and Germans, in the early years of WWII. They constantly had to make really tough decisions on what to go with, small batches of new and improved equipment or bigger numbers of older and perhaps somewhat outdated stuff. Sometimes, not surprisingly, they got it wrong.

 

I would argue that the Germans had their share of "failures" as well. The PzIV with the KwK40 gun was a very good tank in early 1942, it would have been an awesome tank in early 1941 but for reasons I don't know much about it took them that extra year to get it right. A year they could not really afford to lose.

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Actually the 2pdr might have been the 3rd most powerful AT at the time, behind the French 47/60(?) and that ridiculous Russian 57mm.

In theory, in practice 2pdr could not penetrate 50mm StuG IIIe front armor, while US 37mm could at short range.

 

Would you say the following is accurate in gun vs armor in WW2? http://www.wwiiequipment.com/pencalc/

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Apparently there was a shortage of lathes that could produce the 6pdr barrel, which is one reason they went with the shorter barrel version.

 

The UK went to a longer barrel when US lathes were supplied that could take longer blanks.

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And in the end most troops would probably say that an AT gun that is ineffective against the latest tanks is still better than no AT gun. Against older Panzers and Halftracks it still works.

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Actually the 2pdr might have been the 3rd most powerful AT at the time, behind the French 47/60(?) and that ridiculous Russian 57mm.

In theory, in practice 2pdr could not penetrate 50mm StuG IIIe front armor, while US 37mm could at short range.

 

 

Huh? APCR or the lack of it I pressume?

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Setting up a new facotry means that you have to have all new sets of machinery to run the factory. Some things would need re-configuration. Some re-tooling means new jigs and possibly new machinery. A Whole new factory means you need everything, you can't reuse anything.

Expert machinist making new tooling are machinists who aren't making the guns too.

What's somewhat amazing to me is that there are machines from WWII that are still in operation today.

Edited by rmgill
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The thing is, despite that, we did set up new factories making weapons, including large calibre ones, and quite a few of them. This was partly to vastly increase capacity and partly because a single factory in a known location making someth8ng critical to the war effort was obviously a very bad idea, particularly early in the war.

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Setting up a new facotry means that you have to have all new sets of machinery to run the factory. Some things would need re-configuration. Some re-tooling means new jigs and possibly new machinery. A Whole new factory means you need everything, you can't reuse anything.

 

Expert machinist making new tooling are machinists who aren't making the guns too.

 

What's somewhat amazing to me is that there are machines from WWII that are still in operation today.

 

One of the reasons for the choice of 57mm for the AT gun was because there was tooling available going back to Victorian times for the making of naval guns with that bore.

 

The Hotchkiss 6pdr of 1885 had a barrel just three inches shorter than the Ordinance QF 6-pounder 7cwt. Also the coastal twin 6pdr was in production from 1933. Factories were available and producing 6pdr guns, just not 6pdr AT guns.

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One of the reasons for the choice of 57mm for the AT gun was because there was tooling available going back to Victorian times for the making of naval guns with that bore.

 

The Hotchkiss 6pdr of 1885 had a barrel just three inches shorter than the Ordinance QF 6-pounder 7cwt. Also the coastal twin 6pdr was in production from 1933. Factories were available and producing 6pdr guns, just not 6pdr AT guns.

Not so sure. The 1885 gun was 57mm but the performance was way interior to the 1900-ish 47mm gun.

IMO 57mm was just what you did if you were thinking in terms of shell weight.

 

1pdr is 37mm, 2pdr is 40mm, 3pdr is 47mm and so on.

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I am not comparing guns in that way, just remarking that the equipment and tools to make the guns had been available for decades. Of course the British could have chosen a less radical step up from 40mm 2pdr to a 47mm 3pdr AT gun but as there was less manufacturing capacity in Britain for that calibre, the 57mm 6pdr was more able to be manufactured. It should also be remembered that once 6dpr production got started guns were being produced at 1,500 guns a month by May 1942. The 17pdr followed in manufacture and issue the next year.

Edited by DougRichards
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Huh? APCR or the lack of it I pressume?

Capped ammo may be a more likely culprit. For example, Knight in A15 Cruiser Mk.VI Crusader Tank: A Technical History reprints a firing trials chart from mid-1942 where the British found that the front hull of the Pz.Kpfw.III Ausf.H was immune to the 2 pounder when the tank was fitted with the 3 cm applique armor, while the 37 mm gun could punch through at 200-300 yards. The 6 pounder's AP round also suffered, only penetrating at 500-600 yards. The 5 cm frontal armor of the Ausf.L was proof against the 2 pounder from 200 yards, while the 37 mm could get through at 500-600 yards and the 6 pounder 800-900 yards. Col William Blagden, DDAFV, had been asking for 2 pdr ammo with ballistic and piercing caps since March 1942, when it was seen that these features on 37 mm ammo were beneficial. By 24 May Maj-Gen Richard McCreery, the senior officer with responsibility for AFVs at GHQ in Cairo, submitted a note to the CinC stating:

 

 

We urgently require:

 

2-pdr.

 

(a) Higher Velocity

(b ) Piercing Caps

(c ) Ballistic Caps

 

6-pdr.

 

(a) Piercing Caps

(b ) Higher Velocity

(c ) Ballistic Caps

(d) Explosive charge (AP HE)

(e) Nose fuze H.E.

 

All these are believed to be in hand. They have been repeatedly asked for.

 

McCreery reiterated these desires in a 4 June memo to the CGS, Lieut-Gen Thomas Corbett: "We shall have 750 2-pdr Crusaders (after allowing for battle casualties) in M.E. by September, and many will be in use in Armd. Divs. throughout next winter. It is very important therefore to obtain high velocity 2-pdr amn. with both Armor Piercing Caps and Ballistic Caps, so that these 2-pdr. Crusaders can get better penetration against the German tanks at the longer ranges."

 

The StuG's frontal armor was 5 cm until September 1942, so it would correlate with the firing test results for the base armor for the Pz.Kpfw.III Ausf.L.

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Huh? APCR or the lack of it I pressume?

Capped ammo may be a more likely culprit. For example, Knight in A15 Cruiser Mk.VI Crusader Tank: A Technical History reprints a firing trials chart from mid-1942 where the British found that the front hull of the Pz.Kpfw.III Ausf.H was immune to the 2 pounder when the tank was fitted with the 3 cm applique armor, while the 37 mm gun could punch through at 200-300 yards. The 6 pounder's AP round also suffered, only penetrating at 500-600 yards. The 5 cm frontal armor of the Ausf.L was proof against the 2 pounder from 200 yards, while the 37 mm could get through at 500-600 yards and the 6 pounder 800-900 yards. Col William Blagden, DDAFV, had been asking for 2 pdr ammo with ballistic and piercing caps since March 1942, when it was seen that these features on 37 mm ammo were beneficial. By 24 May Maj-Gen Richard McCreery, the senior officer with responsibility for AFVs at GHQ in Cairo, submitted a note to the CinC stating:

 

 

We urgently require:

 

2-pdr.

 

(a) Higher Velocity

(b ) Piercing Caps

(c ) Ballistic Caps

 

6-pdr.

 

(a) Piercing Caps

(b ) Higher Velocity

(c ) Ballistic Caps

(d) Explosive charge (AP HE)

(e) Nose fuze H.E.

 

All these are believed to be in hand. They have been repeatedly asked for.

 

McCreery reiterated these desires in a 4 June memo to the CGS, Lieut-Gen Thomas Corbett: "We shall have 750 2-pdr Crusaders (after allowing for battle casualties) in M.E. by September, and many will be in use in Armd. Divs. throughout next winter. It is very important therefore to obtain high velocity 2-pdr amn. with both Armor Piercing Caps and Ballistic Caps, so that these 2-pdr. Crusaders can get better penetration against the German tanks at the longer ranges."

 

The StuG's frontal armor was 5 cm until September 1942, so it would correlate with the firing test results for the base armor for the Pz.Kpfw.III Ausf.L.

 

 

Ammunition available for the 2pdr included (my source does not indicate dates)

 

Shot AP Mk10T - solid with tracer

 

Shot APCBC Mk 9BT, which has, as implied, ballistic and penetrative caps.

 

Shell AP Mk1 which had a tiny filing of lyddite and base fuse 281, the fuse tended to come away on impact, not firing the filing and even when it worked did not do more damage than solid shot.

 

Shell HE Mk 2T, yes, an HE shell for the 2pdr.

 

500 2pdrs were left behind in France in 1940.

Edited by DougRichards
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"Col William Blagden, DDAFV, had been asking for 2 pdr ammo with ballistic and piercing caps since March 1942, ..."

 

Wow, their ammo didn't even have the soft metal cap(APC)? They were using straight AP. I wouldn't have expected that in 1940, much less 42. I thought APC was the minimum standard around the world at that time.

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