Talk:Ordnance QF 20-pounder

Performance

I've read a couple of times that the performance of the 20-pdr is "about twice that of the 17-pdr", without much by way of explanation of what's meant by that. Twice the penetration at 500 yards? The same penetration at twice the distance? If anyone could expand on that claim (or debunk it) please do so! Chris 22:12, 23 July 2006 (UTC)

I found a similar comparison in Osprey's book on the Centurion (p. 10), in which it states "a 20-pounder APDS round had twice the penetration capability as the fabled 88mm AP round of World War II". If one assumes the 305mm quote for APDS penetration is accurate, this comparison is roughly correct as the 88mm KwK 36 L/56 on the Tiger I could penetrate 127mm of armor at 100 meters with a 30º obliquity, which would approximate to 150mm of armor penetrated at a 0º obliquity. This difference in performance is mostly due to the difference in muzzle velocities, as the 20-pounder APDS round moved over 600 meters per second faster than the Tiger's AP round. W. B. Wilson (talk) 07:47, 26 July 2008 (UTC)

The above comment was edited by an anonymous user. I restored the original text of the comment. Below is the redaction by the anonymous user. Bukvoed (talk) 17:26, 25 August 2008 (UTC)

I found a similar comparison in Osprey's book on the Centurion (p. 10), in which it states "a 20-pounder APDS round had bit better penetration capability as the fabled 88mm AP round of World War II". If one assumes the 205mm quote for APDS penetration is accurate, this comparison is roughly correct as the 88mm KwK 36 L/56 on the Tiger I could penetrate 138mm of armor at 100 meters with a 30º obliquity, which would approximate to 170mm of armor penetrated at a 0º obliquity. This difference in performance is mostly due to the difference in muzzle velocities, as the 20-pounder APDS round moved over 200 meters per second faster than the Tiger's AP round. —Preceding unsigned comment added by 78.92.129.175 (talk • contribs)

Either way, it's a quote from the section talking about increases in performance through the introduction of APDS rounds. It doesn't differentiate between the advantage from muzzle velocity and the advantage from the difference in the projectile. Lkchild (talk) 23:03, 3 July 2016 (UTC)

"In a number of respects, the 20 pounder's design followed that of the German 8.8 cm KwK 43, such as a length of 66.7 calibres and the ability to fire conventional APCBC projectiles."

What kind of sentence even is this? I can't establish a logical correlation between the first and second part of the sentece, and surely not with the end of it. The KwK had a barrel length of 71 calibres, not 66.7, so what are we on about? The APCBC thing? That was the standard projectile of the era! Every gun in that era was optimised to fire APCBC, so following the logic in that sentence we could say that, I don't know, the 20 pounder's design follows the design of the D-25 closely or that of the M1A1, because both of those can fire APCBC. Seriously guys? — Preceding unsigned comment added by 91.82.242.222 (talk) 21:33, 13 July 2015 (UTC)

I just found that it's a direct quote from Technology of Tanks by Ogorkiewicz (page 70). Thats normally a well respected reference, but it sounds like it may be in error. To be fair, it's from a passage discussing ammunition, so details of the gun may have slipped through review. Lkchild (talk) 22:26, 3 July 2016 (UTC)

Comparison Chart

The article states that the 20 pdr fired both APCBC and APDS, but the comparison chart is comparing the subcaliber APDS round in the 20 pdr with full caliber rounds in all the other guns...wouldn't it make more sense to use figures for the APCBC projectile? JDS2005 (talk) 05:20, 17 April 2009 (UTC)

Yes it would, but I haven't been able to find any decent sources. —Preceding unsigned comment added by 77.102.120.98 (talk) 18:43, 6 April 2011 (UTC)

APDS substantially replaced the other types of AP tank gun rounds (with the exception of HESH, which is also useful against concrete emplacements) in the British Army as it's performance was so much better than APC, APBC, APCBC, APCR, So it may be difficult to find figures for these rounds, even if they were designed and made for the 20pdr. In the case of the other guns, APDS rounds were not developed for these, as APDS was a late-war invention by the Brits. — Preceding unsigned comment added by 86.112.68.219 (talk) 19:08, 16 June 2011 (UTC)

The advent of APDS fired from guns such as the 20 pdr and 105mm L7 are what made the Heavy tank obsolete as a tank type post WW II, as the performance of gun and ammunition is so great that it became impracticable to build a successful tank with armour thick enough to protect it.

I have seen this before...

I guess we have the same question here as with L7 article:

"During the Hungarian Revolution of 1956, a Soviet T-54A medium tank was driven onto the grounds of the British embassy in Budapest by the Hungarians. After a brief examination of this tank's armor and 100 mm gun, British officials decided that the 20 pounder was apparently INCAPABLE OF DEFEATING ITS FRONTAL ARMOR."

So why is this still a part of the page if it's a proven lie? We know it was capable of doing alright, it just wasn't providing _complete superiority_ over soviet tank at real battle distances. And that one is mostly affected not by armor of T-54/55, but by its CANNON. Weapon development is usually aiming for superiority with the opponent, not just "catching up". Should those lines be deleted? 37.214.74.83 (talk) 23:14, 5 October 2020 (UTC)

20pdr APDS muzzle velocity

The article does not give anywhere a link to the source for the 1465m/s figure. The reference[5] in that paragraph does not contain this data. So, I ask again, what is the source? Because I have a primary document that shows a much lower figure of 1370m/s. Peasant wiki (talk) 17:51, 12 August 2023 (UTC)

Technology of tanks by Richard M Ogorkiewicz (1991), volume 1, pages 70 and 78 say that the muzzle velocity of APDS from the 83.8mm gun was 1465 m/s.-- Toddy1 (talk) 18:28, 12 August 2023 (UTC)

Armour in Profile (Number 23), Centurion 5, by Michael Norman (1967) page 12 reports the following muzzle velocities (conversion to metric not given in the source):

• Armour Piercing Discarding Sabot (APDS) 4,700 ft/s (1,432.6 m/s)
• High Explosive (HE) 1,975 ft/s (602.0 m/s)
• Canister 3,000 ft/s (914.4 m/s)
• Smoke 825 ft/s (251.5 m/s)

Note that Armour in Profile (Number 23) does not specify which mark of ammunition is meant.-- Toddy1 (talk) 18:41, 12 August 2023 (UTC)

The version of this article of 11:49, 27 July 2008 did not have this table, but it did have the 1465m/s figure, and cited Technology of tanks by Richard M Ogorkiewicz] (1991) page 70 as the source for it. The penetrations figure was cited to British Anti-Tank Gunnery Data.

GraemeLeggett added a table based on Armour in Profile (Number 23), Centurion 5, by Michael Norman (1967) page 12 at 19:17, 4 December 2012.

The current table was added by FORMATOSE at 11:08, 12 November 2022. @FORMATOSE: where did you get the information for this table?. The citation is merely vestigial - left over from an edit that otherwise removed the old table.-- Toddy1 (talk) 20:33, 12 August 2023 (UTC)