203 mm/53 Italian naval gun
- Thread starter Wargames
- Start date
Phoenix_jz
New Member
Hello,
Unfortunately, no data on the 'firing range' penetration values - the type of maximum penetration values usually used for comparing guns across different navies - seems to available for these guns (or indeed most Italian naval guns).
The surviving penetration data we do have is from fleet fighting instructions from September 1942, which do list penetrative values at first charge - but are somewhat conservative and probably not at maximum velocity. Think of them as more 'the shell will definitely penetrate at least this much armor at this thickness and angle at this range' rather than the explicit limit of penetration. They were calculated via a version of the DeMarre formula used by the Regia Marina in this period.
As an additional caveat - the penetration data gives one set of values for both the 203/50 and 203/53, but these should have been using different shells at this point in time - a 118 kg APCBC for the 203/50, and a 125.3 kg for the 203/53. Given the original source lists the characteristics of the 125.3 kg shell and not the 118 kg shell, and that as of September 1942 only one cruiser was left with the 203/50 (Trieste) versus two with the 203/53 (Gorizia & Bolzano), I assume this data reflects the heavier shell.
Two sets of penetration are listed for vertical (belt) penetration, depending on whether the armor is cemented plate or normal homogenous. Obviously, horizontal (deck) penetration has only one set of values, against homogenous armor. Since the original table is a bit messy, I have re-created the tables in Excel. Do note that I inverted the angles so that 0° = perpendicular, with horizontal obliquity increasing with the angle (angle of fall is, of course, already accounted for within the data).
I will also include the original data in this spoiler. Note that the original source reported the angles of obliquity where 90° was a hit perfectly perpendicular to the plate.
A note on reading this data - you will probably notice that the penetration tables for KC armor stop listing values lower than 100mm. That is because that is the effective minimum thickness of cemented plates in this era was 100mm (though if you go back to WWI/pre-WWI you get some plates down to 80mm), so there was no point listing penetration data for KC plates below 100mm.
Unfortunately, no data on the 'firing range' penetration values - the type of maximum penetration values usually used for comparing guns across different navies - seems to available for these guns (or indeed most Italian naval guns).
The surviving penetration data we do have is from fleet fighting instructions from September 1942, which do list penetrative values at first charge - but are somewhat conservative and probably not at maximum velocity. Think of them as more 'the shell will definitely penetrate at least this much armor at this thickness and angle at this range' rather than the explicit limit of penetration. They were calculated via a version of the DeMarre formula used by the Regia Marina in this period.
As an additional caveat - the penetration data gives one set of values for both the 203/50 and 203/53, but these should have been using different shells at this point in time - a 118 kg APCBC for the 203/50, and a 125.3 kg for the 203/53. Given the original source lists the characteristics of the 125.3 kg shell and not the 118 kg shell, and that as of September 1942 only one cruiser was left with the 203/50 (Trieste) versus two with the 203/53 (Gorizia & Bolzano), I assume this data reflects the heavier shell.
Two sets of penetration are listed for vertical (belt) penetration, depending on whether the armor is cemented plate or normal homogenous. Obviously, horizontal (deck) penetration has only one set of values, against homogenous armor. Since the original table is a bit messy, I have re-created the tables in Excel. Do note that I inverted the angles so that 0° = perpendicular, with horizontal obliquity increasing with the angle (angle of fall is, of course, already accounted for within the data).
I will also include the original data in this spoiler. Note that the original source reported the angles of obliquity where 90° was a hit perfectly perpendicular to the plate.
A note on reading this data - you will probably notice that the penetration tables for KC armor stop listing values lower than 100mm. That is because that is the effective minimum thickness of cemented plates in this era was 100mm (though if you go back to WWI/pre-WWI you get some plates down to 80mm), so there was no point listing penetration data for KC plates below 100mm.