Ackley Improved version of Lapua Mag. Shoulder improved to 40°, shoulder dia increased to .570 and neck/ shoulder junction shifted back
.005. Use 338 Lapua Mag Ackley GO gage to set minimum headspace. (Standard GO gage used as Ackley NO GO).
Freebore suitable for magazine feed. For single shot, competition rifles, freebore can be extended to suit the bullet. Use a freebore length
of .190 for Berger 300 gr OTM bullets seated ~.025 forward of neck/shoulder junction and jumping ~.025, based on currently published
bullet dimensions from Berger (bs .515) Will also work well with Sierra 300 gr Mk. Sierra will be seated slightly deeper, to the
neck/shoulder junction. and additional .025-040 freebore can be added for the Sierra if desired. COAL for either bullet will be about 3.90-
3.95.
For solid bullets like the CEB Lazers/MTACs or the Warner Flatlines, .175-.225 fb length is appropriate.

Uses 338 Lapua Ackley GO Gauge and standard 338 Lapua GO Gauge as NO GO