Longbranch No4 Mark I* 6 groove barrell

[Peter Laidler]

We established during student projects that the amount of grooves didn't matter at all. 2, 5 or 6...., it was pretty well academic. What DID count was that the bullet was and remained stable in flight

\i forgot to add that it was critical that it remained spinning in flight too - but that is part of the stability issue