Handloading Winchester’s “THUMPER” – The .350 Legend

THE rules are the same as for any other cartridge that headspaces off the case mouth: with these, the depth to which the cartridge can enter the chamber is controlled by a recess in the chamber which contacts the mouth of the case, and the headspace measurement is the full length of the case itself. Such cartridges cannot be crimped into their bullets, since this would change the headspace. It is, therefore, vitally important not only for accuracy but trouble-free chambering that all of the Legend cases are the same length.

Also, when handloading for hunting, be sure to choose bullets with the proper construction for the size of game and the correct bullet diameter of 0.355-inch. The only exception I made was to try the Hornady 158gn HAP (Action Pistol Bullet which has a diameter of 0.356”) and it fed smoothly, but it’s important to pay close attention to achieving proper crimping. There’s a great deal to be learned about the efficiency of small-capacity straight-wall cases. SAAMI specifies a case length of 1.710”, compared to 1.760 for the parent .223 Rem., and case capacity brim-full averages about 36.5gn of water. Maximum Cartridge Overall Length (C.O.L) should be held to 2.260” – or the