| green beanie | 15 Jun 2013 6:54 p.m. PST |
Did the 6 prd ATG or as the US produce models were called, 57 mm ATG have better luck destroying German tanks than say the 75 mm 1897 ATG that was mounted on the M 3 GMC? Which was the better ATG? |
| Hornswoggler | 15 Jun 2013 9:20 p.m. PST |
On pure performance, the 57mm AT gun had better penetration than the 75mm M1897 with both capped and uncapped rounds. The pros and cons of tactical doctrine, mobility and the effectiveness of the halftrack mount are other questions… |
| Andy ONeill | 16 Jun 2013 2:44 a.m. PST |
The 75 had way better HE, the 6pdr significantly better AP.
I've read some Churchill crews preferred the 6pdr. |
| Trockledockle | 16 Jun 2013 2:56 a.m. PST |
The penetration figures were: 6pdr 74mm @ 1000 yds at 30 degrees
75mm 60mm @ 1000 yds at 30 degrees. The 6pdr was a better A/T gun and that is not too surprising as it was designed as one while the 75mm was a WW1 field gun. The 6pdr was also significantly improved in 1944 by the development of APDS which increased the penetration to 117mm. The 75mm had a great advantage in that it could fire a good HE shell so overall, it was a better tank gun. |
| Martin Rapier | 17 Jun 2013 6:41 a.m. PST |
"I've read some Churchill crews preferred the 6pdr." In Churchill troops it was quite common to retain one 6pdr tank per troop and the other two 75m guns. Of course externally the guns were identical, as the British 75mm was just a rebored and rechambered 6pdr. |
| Neroon | 17 Jun 2013 10:44 a.m. PST |
Of course externally the guns were identical, as the British 75mm was just a rebored and rechambered 6pdr.
Are you sure about that? I was under the impression that the 75mm required an entirely new breech, and that it wasn't the finished barrels that were rebored but rather the cylindrical billets that the barrel was manufactured from that were bored to 75mm. Willing to be educated on this point. cheers |
| Thomas Thomas | 17 Jun 2013 11:42 a.m. PST |
The penetration figures were: 6pdr 74mm @ 1000 yds at 30 degrees
75mm 60mm @ 1000 yds at 30 degrees. The 6pdr was a better A/T gun and that is not too surprising as it was designed as one while the 75mm was a WW1 field gun. The 6pdr was also significantly improved in 1944 by the development of APDS which increased the penetration to 117mm. The 75mm had a great advantage in that it could fire a good HE shell so overall, it was a better tank gun.
Are these figures for the earlier 75mm (based on the French WWI 75mm) or the latter 75L38 in most M4s.
TomT |
| Neroon | 17 Jun 2013 1:39 p.m. PST |
Tim The problem with wiki is that while it provides a good starting point, one really needs other sources for verification and to weed out all the fanboi edits. I find that a lot of the wiki stuff references other wiki stuff (often by the same person) ie circular reasoning. The reason I questioned Martin's statement is that when you look at the 6 pdr barrel there doesn't appear to be sufficient wall thickness to allow them to be bored out to 75mm without bursting the barrel upon firing. (excluding of course the very earliest examples which had extremely thick -and heavy- barrels) Same problem with the breech. Not enough metal to rechamber to the 75mm case without risking a rupture. Still hoping for some accurate info one way or the other. cheers |
| Trockledockle | 18 Jun 2013 12:10 p.m. PST |
Thomas, There are lots of numbers floating about the internet and factors such as angle of impact, test method and ammunition type all have an effect. One set of figures I've found are (1000 yds/30 degrees): 75mm M2 APCBC 55 mm
75mm M3 APCBC 60 mm
6pdr L50 APCBC 74 mm so it looks like it was the longer M3 gun I quoted. The source is the "guns vs armor" site but I get a malware warning if I try to open it. |
| Martin Rapier | 18 Jun 2013 1:06 p.m. PST |
David Fletcher is a little vague, he just says that Vickers developed the 75mm based on the 6pdr so it would fit the existing turret mounting. Chamber for us ammo and rebore the Barrel. 'The Universal Tank' there is more about the various wrangling in the war office, but I can't be bothered to reproduce it here. For the minutiae of how to build tank guns, it would need more detailed books than I possess. |
| Neroon | 18 Jun 2013 3:07 p.m. PST |
Fair enough Martin. I was sure that I had read that somewhere over the last 40 years or so. These days I can't always be certain whether my memory is playing tricks or not. cheers |
| Martin Rapier | 19 Jun 2013 1:53 a.m. PST |
They might have done the barrel too, but I can't find anything definitive. It has picqued my interest and I can tell I'm going to spend a lot of time looking at photos of Churchills to see if there is an obvious difference (apart from the variations I muzzle brakes). I did turn up this photo of the plate next to the QF 75mm at Bovington: link |
