Military zeroing of the No. 4 - inconsistent data?

[Rick]

Bindi's correct with the burn rates between Cordite and modern powders they will never correlate. However on the BC's here is a difference the 2440FPS of the MkVII round is the accepted standard there has been a lot of conjecure but most agree that the MkVII projies BC is around the .467 with the 174SMK at 2200FPS BC being .499 a slight difference to be sure but it reflects on the sight settings.

Relevant to the original question, this morning over coffee I cranked various BC's through the JBM ballistics functions online. The short story is the Canadian military sighting criteria laid out in the pam Shoot To Live cannot result in a 300 yard zero when specifying 8.5" (+/- 1") MPI above POA at 100 yards. Jakester already did the same thing and pointed that out earlier today.

His question to me was along the lines of "One of these two sighting criteria that you found and provided cannot be correct". And when I looked at it after his response, I concluded that he was right that both could not be correct.

Bindi is also correct and I have stated many times get the load where you want it whether its 2440FPS or lower is your choice and do the range time to get the DOPE for your rifle as we have really beaten the skin off this horse time and again you can put into quick load what ever you please to try and figure out a decent load.

I have no idea at this point what his ultimate end game is for this. My suggestion to him when I passed on the info was that the easiest course for him would be to replace the existing Mk2 sight with a Mk1, giving him some click adjustments for elevation across the course. How that rifle came into his possession with a Mk2 sight on it must have a story behind it.

However I do feel this is not the last we will hear from this as it seems top resurface allot what needs to be done is for those wanting answers is to go to the search engine and go throuh the copious threads around this topic.

The question in the original post was why Canadian and British zeroing criteria differed so dramatically despite using the same rifle, the same backsight, and the same ammunition i.e. two inches + difference in MPI at 100 yards, both supposedly resulting in a 300 yard zero.

I can understand some zeroing in on the impossibility of what he said he was attempting to achieve with reloads; what really caught my interest was he was right to tell me the two different zeroing criteria could not both be right. It may be a purely academic question, but it was one I wanted to dig into.

At this point, having done some number crunching at JBM similar to what Jakester did, the Canadian criteria laid out in Shoot To Live simply does not work, no matter what BC you assign to MkVII ammunition.

Given the acknowledgement in the book to British and US SME's as well as Canadians i.e. Lt. Col. Stephen Johnson who had 20 years of success as one of Canada's best shooters and five times on the Bisley team, you would think that at some point SAIs (or musketry instructors at that time) would have pointed out that the zeroing criteria in the official pam simply was not correct. Shoot To Live, although I haven't thoroughly read it from cover to cover, is otherwise a pretty good pam, and its' roots certainly show up in the later editions of Shoot To Live. B-GL-382-001/PT-001, in 2004, was I think, the final version of Shoot To Live before being replaced by B-GL-382-001/PT-001 Canadian Forces Operational Shooting Program in 2007. Afghanistan apparently made the military decide some changes were required...

That aside, what his ultimate objective is, I cannot even guess. One thing he and that Lee Enfield will never lack is range time, however.

Use my load data at your own peril as I have no control how you may reload your rounds not saying youre not safe reloaders just its a sue your ar*se off world and I am not going to be held responsible for a load that is safe in my rifles but may not be in another shooters rifles. Cheers

Thanks for that; I'll pass it on if he asks for reloading data.

I doubt very much that he will be doing any reloads that get to book maximums for any powder or bullet manufacturer; having watched him reload for about two decades now, he's never shown any particular interest in trying to wring the last few fps out of any load. And that in itself might make his attempt even more difficult.

There's a few Canadian Rangers that are/were DCRA competitors and I think also shot at CAFSAC kicking around on other forums if they aren't members here as well. My curiosity about the error in Shoot To Live is now well piqued; I think I should try and track a few of them down and ask them more about the zeroing criteria they used in their patrols and in particular in preparation for CAFSAC, although Ranger issue ammunition (at least recently at the end of the No 4 service time) wasn't Mk VII or an exact equivalent.

Thanks again, CINDERS