Nakihunter,

Yes, this is nitro-for-black loading. I am substituting IMR4198 with appropriate wads, for the original black powder charge. The object is to duplicate the exterior ballistics of the original load, thus achieving proper regulation, with the use of smokeless (nitro) powder.

Done properly, it is documented that the nitro-for-black loading results in substantially less internal pressure. Graeme Wright does not report pressure tests for the .577 2 3/4" BPE. However, his pressure tests on the .577 3" BPE demonstrated that he could duplicate the ballistics of the original nitro-for-black factory load (pressure of 10 tons) at only 7.8 tons pressure using Varget and 8.9 tons using H4198.

Curl