Two bullets for ID

[epmg]

Two bullets I dug up on the Sussex coast, the one on the right is obviously damaged. Both have a mystery black filling in the core, but I suspect both are WWII. Any ID help appreciated. Thanks. Left: 11mm diameter, 15mm long Right: 7mm diameter, 30mm long.

[MilitaryMetalMagnut]

On the left is a .45 ACP, which would be American made. The rifling marks are a right hand twist so would very likely have been fired from a Thompson SMG. The other is a .303 Mk VII ‘ball’ (bog standard round of ammunition). Five grooves left hand twist is from a Lee Enfield rifle.
Both will be WW2 vintage, and the black core is just oxidised lead.

Best regards,

Simon

[epmg]

Thanks Simon, interesting that the rifling twist marks on fired bullets can be be so indicative. Is there a reason why some weapons have left twist and others right?

[ManOnTheMoon]

Thanks Simon, interesting that the rifling twist marks on fired bullets can be be so indicative. Is there a reason why some weapons have left twist and others right?

Simon will, of course, have an authoritative answer to your question, but my instinctive guess is that it is likely similar to why some countries drive on the right, or left, side of a road - it was just a choice made at that time. I don't think it affects the quality of the weapon or how it performs, when measured against another of similar capability.

To be clear, I am not an expert on the subject of rifling, but I have had opportunity to handle and fire several varieties of small arms, both short and long barrel, manufactured in both Western and Eastern bloc countries. This was the result of spending two+ decades in the military, and if Simon, or anyone else here, knows of a technical reason for left-hand or right-hand rifling, I would be interested to hear it.

[MilitaryMetalMagnut]

Thanks ManontheMoon for the 'prod'!

I don’t believe there is any real difference in benefit between left or right rifling spin. From my experience of .22LR target shooting, it’s good to keep in mind which way your rifling turns, especially when shooting outdoors. For example, my .22LR target rifle has a right hand twist, so if I’m shooting outside and there’s a steady amount of wind blowing straight at me, then I can expect the shots to be slightly high and right on the target. Although, this only really affects subsonic bullets like my .22LR, but with things like .303’s they’re traveling much faster than the speed of sound at 2450fps so a head on wind won’t really make any difference, certainly not at short ranges. A .22LR rifle with a left hand twist and a bit of head wind would be slightly high and left on the target. The wind and spin of the bullet creates a Venturi effect which lifts it very slightly. It’s only very slight and when you’re trying to shoot hole on hole accuracy, but it’s one of those things that add up!

Best regards,

Simon

[ManOnTheMoon]

Thanks, Simon, that is interesting information.