As far as I know, the projectile for the L48 had to have reduced explosive charge (the problem was that spent cartridges would not eject), which reduced the velocity down to L43 levels.
Was this a problem only for PzIV mounted guns, or was it a problem for STUG mounts, too?
75L48 KWK
75L48 KWK
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Christian Ankerstjerne
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Re: 75L48 KWK
The 7,5 cm Stu K 40 and 7,5 cm Kw K 40 used the same ammunition. Both had a somewhat reduced charge when compared to the 7,5 cm Pak 40, but not by much. From D 435-1 (main charge only):
- 7,5 cm Sprgr. Patr. 34 Pak 40: 780 g
- 7,5 cm Sprgr. Patr. 34 Kw. K. 40: 755 g
- 7,5 cm Pzgr. Patr. 39 Pak. 40: 2 750 g
- 7,5 cm Pzgr. Patr. 39 Kw. K. 40: 2 430 g
- 7,5 cm Pzgr. Patr. 40 Pak. 40: 2 700 g
- 7,5 cm Pzgr. Patr. 40 Kw. K. 40: 2 180 g
- 7,5 cm Gr. Patr. 38 Hl/B Pak. 40: 490 g
- 7,5 cm Gr. Patr. 38 Hl/B Kw. K. 40: 430 g
Re: 75L48 KWK
I have German records that state the muzzle velocity of the 75mm KwK 40 L/48 at 790 m/s (perhaps they were measured before the reduction), the reduced charge would have lowered the muzzle velocity into the 770-780m/s range based on Allied measurements.
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Yoozername
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Re: 75L48 KWK
The 7,5 cm Pzgr. Patr. 39 (KWK 40 and StuK 40) was initially 2.43 Kg. It was actually increased, according to a October 1944 document, to 2.5 Kg. There was a 'Fur Tropen' reduced charge but it was, as it name implies, meant for North Afrika, etc. I believe it was 2.16 Kg.
The 7,5 cm Pazgr. Patr. 39 (PAK 40) was 2.75 Kg initially, and I have not seen any documentation stating it was reduced. In December 1942, it was still 2.75 Kg in German documents.
The L48 was introduced into the StuG III quite awhile before the Panzer IV, which kept the L43 weapon longer. If there is any real issue (I think this is all BS as far as 'reduced velocity'), it would be a StuG III issue during 1942 when the StuG was first armed with the L48.
The initial L48 barrels were the same increasing 'twist rate (progressive twist) as the L43 and L46, and from what I have read, the velocities were very high using the standard ammunition. I believe these were the 'Messen' trials in 1942. The barrels for the L48 were then redesigned for a constant twist rate.
The issue of failure to automatically eject is the cited issue. In some cases, even manually ejection was an issue, and the option to go outside and use a ramrod to push the cartridge back out. This was an issue with certain 50mm weapons also, if I can recall, that fired the high velocity tungsten ammunition.
An interesting thing with the KWK/StuK 40 and PAK 40, is the great difference in powder charge between the Patr 40 rounds (tungsten). The 4.1 Kg projectile is shot with 2.18 Kg in the L43/48 weapons, and 2.7 Kg in the PAK 40 weapon. Velocities for these are often stated in the 930 M/s or 990 m/s range. I personally believe that the PAK 40 using the Patr 40 tungsten rounds may have been extremely rare to almost non-existant later in the war. They had the velocity to deal with nearly all 1942-1943 Soviet tanks and could still be a threat in 1944 to most.
I believe that there never was a reduced charge for the StuK weapon, but the first 400 twist rate barrel weapons may have had issues when firing the standard ammunition. They may have used 'Fur Tropen' ammunition as an expedient.
As far as velocities go, I lean towards the L43 weapon, firing the later 2.5 Kg standard round being 750 m/s. The L48 weapons, with constant twist barrels, being 770 m/s. The PAK 40 does not ever seem to change and is 790 m/s.
The 7,5 cm Pazgr. Patr. 39 (PAK 40) was 2.75 Kg initially, and I have not seen any documentation stating it was reduced. In December 1942, it was still 2.75 Kg in German documents.
The L48 was introduced into the StuG III quite awhile before the Panzer IV, which kept the L43 weapon longer. If there is any real issue (I think this is all BS as far as 'reduced velocity'), it would be a StuG III issue during 1942 when the StuG was first armed with the L48.
The initial L48 barrels were the same increasing 'twist rate (progressive twist) as the L43 and L46, and from what I have read, the velocities were very high using the standard ammunition. I believe these were the 'Messen' trials in 1942. The barrels for the L48 were then redesigned for a constant twist rate.
The issue of failure to automatically eject is the cited issue. In some cases, even manually ejection was an issue, and the option to go outside and use a ramrod to push the cartridge back out. This was an issue with certain 50mm weapons also, if I can recall, that fired the high velocity tungsten ammunition.
An interesting thing with the KWK/StuK 40 and PAK 40, is the great difference in powder charge between the Patr 40 rounds (tungsten). The 4.1 Kg projectile is shot with 2.18 Kg in the L43/48 weapons, and 2.7 Kg in the PAK 40 weapon. Velocities for these are often stated in the 930 M/s or 990 m/s range. I personally believe that the PAK 40 using the Patr 40 tungsten rounds may have been extremely rare to almost non-existant later in the war. They had the velocity to deal with nearly all 1942-1943 Soviet tanks and could still be a threat in 1944 to most.
I believe that there never was a reduced charge for the StuK weapon, but the first 400 twist rate barrel weapons may have had issues when firing the standard ammunition. They may have used 'Fur Tropen' ammunition as an expedient.
As far as velocities go, I lean towards the L43 weapon, firing the later 2.5 Kg standard round being 750 m/s. The L48 weapons, with constant twist barrels, being 770 m/s. The PAK 40 does not ever seem to change and is 790 m/s.
Re: 75L48 KWK
Ty, for the information.
I trying to think where I have the Allied numbers for 770m/s....I don't recall if there were penetration figures...... I suppose it should be somewhere in between the L/43 and the Pak 40.
I trying to think where I have the Allied numbers for 770m/s....I don't recall if there were penetration figures...... I suppose it should be somewhere in between the L/43 and the Pak 40.
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Yoozername
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Re: 75L48 KWK
If you look at Merkblatt 28/1 (April 1, 1944), it again confirms that PAK 40 pzgr 39 had 2.73 Kg of propellant. I think the whole "reduced to 750 M/s velocity" myth has taken on a life thanks to the internet. There are actually at least three documents during the war that show the PAK 40 had the same or very nearly the same weight of propellant. It seems that even author like Carruthers has parroted this.
The PAK 40 also seems to have been a minimal user of Pzgr 40. Numbers indicate scarcity much below KWK 40 weapons and even captured/converted Soviet weapons. Its scarcity may have been on the same level as the Panther Pzgr 40/42!
The PAK 40 'may' have converted to a uniform twist barrel. Its original twist rate was an increasing twist and quite aggressive (like the KWK L43).
The KWK 40 weapons, which includes the L43 and L48, and the PAK 39 (Hetzer and Jgdpanzer IV L48), all shared the same ammunition. Early versions were 2.43 Kg and later versions were 2.54 Kg of propellant. Again, there is no reduction. In fact, there is an increase.
So I still believe...As far as velocities go, I lean towards the L43 weapon, firing the later 2.54 Kg standard propellant round being 750 m/s. The L48 weapons, with constant twist barrels, being 770 m/s. The PAK 40 does not ever seem to change and is 790 m/s.
If anyone has any information regarding this, I would sure like to hear it.
The PAK 40 also seems to have been a minimal user of Pzgr 40. Numbers indicate scarcity much below KWK 40 weapons and even captured/converted Soviet weapons. Its scarcity may have been on the same level as the Panther Pzgr 40/42!
The PAK 40 'may' have converted to a uniform twist barrel. Its original twist rate was an increasing twist and quite aggressive (like the KWK L43).
The KWK 40 weapons, which includes the L43 and L48, and the PAK 39 (Hetzer and Jgdpanzer IV L48), all shared the same ammunition. Early versions were 2.43 Kg and later versions were 2.54 Kg of propellant. Again, there is no reduction. In fact, there is an increase.
So I still believe...As far as velocities go, I lean towards the L43 weapon, firing the later 2.54 Kg standard propellant round being 750 m/s. The L48 weapons, with constant twist barrels, being 770 m/s. The PAK 40 does not ever seem to change and is 790 m/s.
If anyone has any information regarding this, I would sure like to hear it.
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Yoozername
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Re: 75L48 KWK
The Germans also had multiple propellant types, but for the 7,5 cm weapons, they used the same type during the war for Pzgr 39. Mostly, the HE and HEAT and Smoke and even AP40 had alternative fillings. These must have, of course, given them the same velocities in most cases (ex: AP40).Christian Ankerstjerne wrote:The 7,5 cm Stu K 40 and 7,5 cm Kw K 40 used the same ammunition. Both had a somewhat reduced charge when compared to the 7,5 cm Pak 40, but not by much. From D 435-1 (main charge only):
- 7,5 cm Sprgr. Patr. 34 Pak 40: 780 g
- 7,5 cm Sprgr. Patr. 34 Kw. K. 40: 755 g
- 7,5 cm Pzgr. Patr. 39 Pak. 40: 2 750 g
- 7,5 cm Pzgr. Patr. 39 Kw. K. 40: 2 430 g (increased to 2.54 Kg)
- 7,5 cm Pzgr. Patr. 40 Pak. 40: 2 700 g (rare and varied by propellant and weight)
- 7,5 cm Pzgr. Patr. 40 Kw. K. 40: 2 180 g
- 7,5 cm Gr. Patr. 38 Hl/B Pak. 40: 490 g
- 7,5 cm Gr. Patr. 38 Hl/B Kw. K. 40: 430 g
Most weapons had Hl/C by April '44 BTW, since documentation usually lagged fielding, I would think as soon as December 43.
I question the actual velocities as far as HE.