I found an interesting description of Lightning powder in Narramore's book "Principles and Practice of Loading Ammunition". Quote, in part:
"The tolerance [for pressure] is rather narrow for a double-base powder and is intended for regular jacketed bullet loads in medium cartridges of the .30-30 class.
...It's balance point is somewhere around 30,000psi, and it should not be used in charges developing over 40,000psi. It can be used with gas-checked bullets in the larger cartridges, in fact, it is the best gas-check bullet powder there is for 500 yard loads in the .30-06. Lightning is not a satisfactory powder for most small cartridges nor is it particularly good with plain-base bullets. The powder is still being made for the ammunition industry but is not being put out in canisters at the present [1954]."
He lists some loads for .25's as follows:
.25-35, 117 gr. bullet, 17.7gr.
.250-3000, 100gr. bullet, 23.5gr.
.257 Roberts, 87gr., 31.2gr. 100gr., 29.4gr.
Several other loads are listed for cast lead bullets. If interested, PM me.
No velocities listed for any of his charge recommendations.
Seating depths and OALs are listed however. If interested, PM me.
Sharpe, as you probably know, describes two different Lightning powders in his treatise, Lightning #1 and Lightning #2, with detailed physical descriptions. Which do you have? Some of his data:
.250-3000, 87gr., 29.9gr.=3000fps, 44,000(?- no unit of measure)
.25 Krag- nothing
.25/06 Niedner- nothing
.25 G&H and Niedner-Roberts- nothing
.257 Roberts, 87gr., 21.0gr.= 2165fps
29.0gr.= 2820fps, 36,000(?)
33.2gr.= 3160fps, 50,000(?)!
100gr.,19.0gr.= 1950fps
26.0gr.= 2445fps, 31,400(?)
31.3gr.= 2830fps, 50,000(?)!
Again all loads with jacketed bullets. I can look up cast loads if needed.
He notes that all of the above loads for Lightning were recommended by the Hercules powder company.
I always got the impression that Narramore operated on the conservative side of things. Sharpe, not so much.
Hope this helps.
Gary
Last edited by Gary D.; 05/15/11 09:17 AM.
