Interesting bullet holes - Explain this?

[1066]

Not mine - I've just seen this in another place. I'm sure we've all seen the odd tumbled bullet over the years but this is the first time if noticed this. Firstly they are all dead flat sideways as they hit the target and all pointing in the 19.00 position. What sort of gyroscopic action could possibly cause that. Anyone noticed anything like that before?
Apparently it's a .223, 80gn bullet with a 1/14 barrel so no surprise they are all over the show.

[meles meles]

" Ouch "

[hitchphil]

That's more like a map of the disposition of ships at Midway - the 4 scrubbed out are obs the carriers !

[snayperskaya]

My guess would be he wrong twist rate for the bullet weight/bullet length and the bullet tumbling as a result of instability from not spinning fast enough ,I would have thought a 1:7 or 1:8 twist rate would suit a 80gr bullet better.......

[Laurie]

Yes, I've seen that before, same set of players too. The Sg value will have been so low here that the bullets flew more or less nose-first as far as the target and as soon as the tip hit it the whole projectile is tipped sideways and goes through the paper that way. I'd assume the symmetry in their alignment is a result of the right-hand spin throwing each one onto the paper the same way. Remember, nearly all bullets are base-heavy, so they'll turn quickly once the movement starts.

Often marginally stabilised bullets will produce round holes at short range, but near-perfect silhouettes like those in the pic at long ranges.

When the rate of spin / bullet stability is more marginal, (as in shooting the 90gn SMK in an 8-twist 223, too long a bullet but not by a vast amount), you get an oval / elongated hole at short-range caused by the bullet tipping as a result of the upset caused by tip contact but here passing through the target still more or less tip-first and just starting to tip sideways as it does so. I can't remember now if the holes were randomly or uniformly aligned.

[BamBam]

55gr will only just stabilise in a 1-14.

[dromia]

I've seen that when someone I know shot 303 rounds through a 8x56R Steyr Mannlicher.

[1066]

That's more like a map of the disposition of ships at Midway - the 4 scrubbed out are obs the carriers !

[1066]

Yes, I've seen that before, same set of players too. The Sg value will have been so low here that the bullets flew more or less nose-first as far as the target and as soon as the tip hit it the whole projectile is tipped sideways and goes through the paper that way. I'd assume the symmetry in their alignment is a result of the right-hand spin throwing each one onto the paper the same way. Remember, nearly all bullets are base-heavy, so they'll turn quickly once the movement starts.

Often marginally stabilised bullets will produce round holes at short range, but near-perfect silhouettes like those in the pic at long ranges.

When the rate of spin / bullet stability is more marginal, (as in shooting the 90gn SMK in an 8-twist 223, too long a bullet but not by a vast amount), you get an oval / elongated hole at short-range caused by the bullet tipping as a result of the upset caused by tip contact but here passing through the target still more or less tip-first and just starting to tip sideways as it does so. I can't remember now if the holes were randomly or uniformly aligned.

Ahh - that makes sense Laurie, and would explain the alignment - Never given it a thought before, I guess I thought that any I've seen like that, making the perfect silhouette, turned at some point to fly through the air sideways. I would guess there would need to be several stars aligned for it to happen, right range, velocity and stability (lack of). - Never too old to learn. :)

[1066]

55gr will only just stabilise in a 1-14.

Love the caption on the photo. :)