This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.
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having re-read an old post , i thought it would be fun to exactly scale down a tank round to small arms size....keeping the proportions identical
to qualitfy as small arms, i limited the muzzle energy to 6000ft lbs.....a bit higher than 338
SIZE OF DART
to match the 5700fps of a tank round, the tungsten dart would have to be 85 grain. This means that it's diameter would be 2mm (some of the tungsten SPEW darts were 1.5mm/37grain, so increasing to 2mm means about 85grain)
Dart length would be 60mm, compared to 40mm for the SPEW/ACR darts
tank rounds have a sabot which is nearly as heavy as the projectile....this is a huge amount of parasitic mass. Thus our sabot would be about 75grains. This presumably means that we'd need about 10, 000ft lbs, instead of 6,000....unless i'm wrong
SABOT / BORE DIAMETER
with the dart being 2mm, you'd need a 10mm bore to stay proportionate to a tank round. This is much wider than the normal .22 bore used by the SPEW/ACR flechette guns
this is unlikely to be as efficient as a wider 3mm-4mm dart. The tank-proportioned 2mm dart is just ridiculously thin, i suspect it would just shatter, unlike a wider 4mm dart
i don't know the length of an abrams or challenger barrel, perhaps someone can scale it down to get a rough barrel length for the rifle
it's clear that this approach of perfectly scaling down would not be efficient. The bore is insanely wide, the sabot is too heavy , increasig parasitic mass, and the dart is impractically thin
this tells us that if you wanted reasonable APFSDS efficiency, you'd want something roughly twice as powerful, with a wider 4mm dart
We've had a similar debate on this forum eons ago.
Briefly, fluid dynamics is far more complex than 'let's just scale things up and down'. Scaling tank pills down to small arms pills doesn't really work very well, as the SPIW program proved.
Additionally, you can have 'too much of a good thing'; darts at such high speeds as you're proposing will probably bend / break upon impact, which would drastically reduce the AP capabilities.
Last but not least, penetration dynamics of a human body are vastly different from the dynamics of metals, ceramics... so even if the penetration is reasonable (a very big if), the effects will probably be too light to really matter.