Re: 338 (250 grain) Lapua Scenar dimensions
The length of the entire bullet is 39.50mm. The boat tail is 6.25mm. The shank is 14mm on several of my bullets so I would guess they told you too long of a shank length. The nose is very long and sleek. Incidentally, the boat tail on this Scenar is longer than the boat tail on the 300 grain MK from Sierra and a hell of a lot more consistent in length and weight than ANY Sierra I've ever measured!
By your intentions of making this bullet run through a magazine, I gather you intend to hunt with it?
If so, you might want to check out the thread I started on "338 thunder project" and also on "Scenar bullet failure...no really it was bad".
This might change your mind about hunting with this bullet unless it is open season on tanks!
If it's not far, it's boring.