The M1917 is a rifle with a good, long barrel and a good, long sight radius.
The best results I achieved were using Sierra 168 gn MatchKing bullets, set 0.5mm off the lands. The cases were neck-sized only, leaving a very small un-re sized section (about 0.5 mm) of neck that serves to center the resized neck in the chamber.
The powder was Vihtavuori N140. I have no test results for other powders.
Attachment 99306
Each load was fired with 8 shots. Iron sights, off a sandbag. 9 groups of 8 shots = 72 shots. A very long session, with breaks for "eyeball" recuperation.
Since a one can always make a bad shot, I established two curves of group sizes - one including all shots, and one where the worst shot from each group was eliminated.
One important thing I learnt from these tests: people write at length about finding the
best load. But it is easier to find the WORST loads and then pick a value in between two obviously bad loads!
You can see from the graphs that 50 gn is a very good load. It is, however, also a shoulder punisher. Indeed, the Vihtavuori reloading manual gives 50.1 gn as the "accuracy load", but I am not keen on overstraining either the rifle or myself. 48 gn is much more comfortable, and you are unlikely to be able to detect any difference unless you are shooting long strings using a scope.
I calculated that the optimum value would be around 47.8 gn. Now you can reload as carefully as you like, but a good load should have a bit of tolerance. So I simply take the load as 48 gn with an allowable tolerance on the powder scales of +0.0 / -0.1 gn.
That is the weigher indication, of course. If you were to check the loads on a chemical balance, the variation would be somewhat larger, but as you can see from the graphs, a spread of 0.2 gn is not going to make any difference.
This reloading recipe allows my M1917 to achieve 1 MOA with a scope fitted. With iron sights, the accuracy is "shooter eyesight limited".
Good shooting with your "American Enfields"
Patrick
