Quote Originally Posted by Bindi2 View Post
The bit you are missing is the difference in barrel harmonics between the two charges.
Thanks for the suggestion. But if that's so, the authors at Higher Niner of the various nations' pams, the 1950 Armourers' Precis, Reynolds, et al similarly also didn't notice the difference in barrel harmonics between the two charges in any version of the rifle.

None noticed sufficiently to even making mention of a significant difference in barrel harmonics between Cordite and NC loads, resulting in conflicting different zeroing data being required as in the Canadian Shoot To Live, based on whichever type of propellant was loaded.

As NC apparently was first introduced at the end of WW 1, and Cordite loaded ammunition was still in the supply system through WWII and then Korea, there is no certainty that a Commonwealth nation whose troops were in battle could be exclusively supplied with either Cordite or NC based ball ammunition to match whatever the troops' rifles were zeroed with prior to being sent into battle.

And a 2.5+/- MOA difference in zeroing is well over the difference of a single change in front sight blade height. So I would presume that Higher Niner, the ones developing and updating the pams throughout the service life of the rifle would have taken such a significant difference into account - even if only a simple notation somewhere within at least one of those publications, whatever version of the Lee Enfield it was attached to.

To fuel my academic curiosity about the two very different zeroing specifications, I have a range document from inside the Canadian Rangers with this related to zeroing their No.4 rifles:
LE Sites are calibrated to 174gr Spitzer Point Flat Base Mk7 Ammunition. Rangers are issued 175gr Spitzer Point Boat Tail Mk8Z Ammunition... Desired Point of Impact: 8.5" above the point of aim.
If Mk8z ammunition manufactured by IVI (or whoever in Canadaicon) in the 1980's for the Rangers is in fact correct, at the suggested velocities for Mk8z ball ammunition, you would expect an even flatter ballistic parabola, and an even LOWER height above point of aim at 100 yards to obtain POA=POI at 300 yards.
[there's some confounding factors in these instructions in that the paper instructs zeroing at 100 meters, not yards, for a zero at 300 meters, not yards. And of course, with their issue sights calibrated for yards, I haven't bothered yet to see if a ballistic calculator says that a +8.5" POI works when sighting using metric instead of yards. I think a calculation of those ballistics, even with 300 meters being longer than 300 yards, you will still be lower than +8.5" at 100 meters to be zeroed with the 300 yard aperture at 300 meters.]
A shooting/rifle obsessed friend just retired as the RSM of his unit, and promptly joined the Canadian Ranger patrol nearest him. The Lee Enfield has been gone for a couple of years now, but I'm going to ask Gary if he can prowl what they have in the way of pams to see if they have anything there that relates to thus point of curiosity.

I also know Russ Meades as an acquaintance from way back in the day when he arrived here from the UK and enlisted in the Canadian military. Russ was pretty keen on shooting back in the day, and he ended his career decades later as the officer in charge of the Canadian Rangers; perhaps he can shed any light on it.

And finally, my brother retired from 30 years working at BATUS as a civilian whose working days were spent working beside Britishicon REMEs on the Challenger tanks and everything else mechanical that moved. He told me yesterday that one of the REMEs who stayed here is a Lee Enfield obsessed rifle nut, a good friend of his who I helped secure the recovery of a Land Rover (but why????), found multiple NATO documents on their military version of the DWAN that he printed out, which might relate to zeroing specifications. So perhaps there is something there as well...

Again, at this point it's purely an academic curiosity now that all the worthwhile Mk VII seems to have disappeared forever. But I do find a 2.5 MOA difference at 100 yards while zeroing these rifles to be interesting, with the Canadian disagreement with the other Commonwealth pams relating to zeroing this rifle.

Thanks again for the suggestions!