Weapon Accuracy

[rexford]

John Salt's Snippets present the results from two WO reports which show the inferiority of APDS to APCBC ammo in terms of accuracy, and also indicate how much variation in weapon accuracy could be experienced.

WO 291/762 deals with 6 pdr firing tests using APCBC (2725 fps muzzle velocity) and APDS ammo (3950 fps muzzle velocity), where the target is a 5' long by 2' high object which represents the Panther turret.

The overall hit percentages were (ranges in yards, 5 tanks used in tests):

Best 3 Tanks Firing APDS

74% at 500

50% at 800

37% at 1000

20% at 1500

Best 3 Tanks Firing APCBC

89% at 500

84% at 800

81% at 1000

62% at 1500

Worst 2 Tanks firing APCBC

52% at 500

57% at 800

34% at 1000

12% at 1500

Judging from the report stats the tanks initially did not have the range down precisely and started out using an estimate.

As might be expected the best shooters with APCBC oudperformed the best APDS trials by a wide margin.

What is somewhat unexpected is the large difference between the APCBC firing trials for the best 3 and the worst 2. To obtain the listed hit probabilities at all ranges, the 6 pdr guns would have to be superior to the German 50 L60 APC and 88 L56 APCBC in terms of random scatter with a fixed aim (where those two German rounds had extremely small dispersion with fixed aim).

WO 291/1263 presents 17 pdr firing trials with APDS and APCBC where the APDS round is clearly inferior to APCBC:

400 yards

91% for APCBC, 57% for APDS

600 yards

73% for APCBC, 34% for APDS

800 yards

57% for APCBC, 22% for APDS

1000 yards

45% for APCBC, 15% for APDS

1500 yards

25% for APCBC, 7% for APDS

In terms of random scatter with fixed aim, the APDS rounds appear to have about twice the dispersion of the APCBC ammo. If some of the APDS rounds performed as designed with small scatter, the average dispersion of the "bad" APDS might be considerably more than twice the APCBC average.

The WO report notes that a flank observer could not detect the APDS tracer in 73% of the cases, and in no case was the APDS trace seen from inside the tank. A buttoned-up Firefly would appear to have a difficult time picking up the trace on missed shots with APDS, further decreasing the accuracy of the rounds.

[Michael Emrys]

It would appear that despite its enhanced penetration, APDS at the end of the day may not have really been all that useful, especially at ranges beyond 500 meters. Food for thought.

Michael

[rexford]

Originally posted by Michael Emrys:

It would appear that despite its enhanced penetration, APDS at the end of the day may not have really been all that useful, especially at ranges beyond 500 meters. Food for thought.

Michael

The APDS round not only was poor accuracy wise, but the same problem that caused the poor accuracy (uneven shedding of sabot petals) greatly lowered the penetration due to yaw (projectile angle at impact is different from overall flight path or trajectory).