Yes I like modern guns, but I like old guns too. There's more purity in reloading for and shooting old guns. It's a different process for me. I did the loading old school and shut off the electric auto-dispenser when doing these. It makes for a more wholesome, intimate experience, and renews some techniques that I haven't used in a long time.
MKVII ball is 2440 FPS, according to the Sierra book. It can be done with 3031 if you push their listed max load up a little. Hornaday's book is a little more potent on loadings, but they don't list 3031 if I recall correctly, for that weight, anyway. Lyman and Sierra are about the same. All three mfg's used No4 Mk2 rifles for their load development. So there's no pressure data. (Not surprising).
I used Sierra data to start with, but plan on chronographing these loads to get the story from the rifle. I'll track the loads in a spreadsheet just like I do my precision bolt guns. I've heard Enfield bores are kind of like fingerprints, no two alike, so just like my precision bolt guns, I'll load to the gun, not the book.
For newer reloaders who would wonder why a person would exceed a listed maximum on an old gun; the listed data in the Sierra books are in blocks of 100FPS. A listed maximum means that "somewhere between this number and where the next number would be you will hit max pressure".
Other books list an explicit "MAX" - but again on this rifle there's no PRESSURE data listed, so you know they just observed, that on THEIR rifle, this is where they A) found pressure signs, or B) filled the case to capacity with powder and didn't push forward with drop tubes.
Basically it's a flag to
step it up slowly to and from that point and watch for pressure signs in the brass. On a big 30 cal case there's a couple grains of weight, between point A and point B. It may mean that listed max is on the nose, and you'll see pressure signs in your rifle at that mark. But generally I've found this is not true, you can go a little higher than listed, until you start to see pressure. In this case to hit the spec with 3031, you're "40% to the next step". No two rifles will be the same and the rifle won't answer if you ask it, even nicely, so the only way to find out, is to try, and observe.
EDIT:
Other tricks exist for "modulating pressure". On my 300 Win Mag, for instance, I can increase case capacity slightly as I know precisely where my lands are, and I can load the bullet out to them. Pressure will slightly decrease as you move the bullet forward in the casing, for any given volume of powder, and then sharply increase again once you start touching the lands of the rifling. Each bullet type (mfg/weight/style) has a different shape so each one has to be figured out on it's own.
Bore matters as well, especially on old guns which weren't machined off of highly precise tolerances. Was the reamer used on my rifle the precise same size as another guy's? Was it worn down? Has the bore's rifling been worn? Has the throat eroded? Is the bore truly centered in the barrel? Is the bore curved? (It happens that sometimes there's a slight curve in some older barrels)
All of these questions - and the answers to them, affect how your bullet goes down the barrel, and will also affect pressure.
Anyway enough of a lecture for one day.
