Range Report What is the purpose of the tail on Lapua's Lock Base bullets?

[dbooksta]

I just pulled a factory Lapua .338LM 250gr Lock Base and had never seen a bullet with this ... sprue? ... in the base before. What is the purpose of this design?

My best guess is that it's like an open-tip in reverse – i.e., the jacket is drawn from the tip to the tail. So it saves the trouble of pointing an open-tip? Or does it have some other purpose or advantage over OTM profiles?

 

[TA338]

Lapua wantewd to make a more accurate and more pressure tolerant target FMJ-bullet than D46. D46 rebated tail does not tolerate well 300 Win Mag pressures and accuracy suffers with max loads. LoackBase has a tapered base which tolerates much higher pressures without worsening accuracy. If you do not need FMJ bullets then Scenars are probably more accurate. LockBase bullets were first developed for 338 Lapua Magnum FMJ military load. Then thry developed 150 and 170 LB bullets for 308. 170 LB bullet is or at least was once used by Brits and Australia in their AI sniper rifles.

 

[dbooksta]

Ah ha: So the LB was likely created to provide better accuracy (under broader loads) than the D46 while still satisfying conservative legal interpretations of the Hague Conventions.

Before considering that I was also wondering if the closed tip might offer the benefit of a consistent point vs. the "unpointed" Scenar/OTM styles?