I had got this in an email from Ed Harris several years ago...he used to write articles for "The American Rifleman".
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"SERVICE RIFLE" loads approximate the performance, and accuracy of military "ball" or "match" ammunition for target shooting over the National Match Course. It is important that the powder
charge, bullet type, and ballistic parameters not vary significantly from arsenal ammunition, in order to ensure they function as intended in semi-automatic, quasi-military arms.
The ballistics of Ball M2 service ammunition, (2740 +/- 30 f.p.s.) with a 150-gr. spitzer, flatbased bullet are approximated in GI cases with a charge of 47.5 grs. of current Hodgdon or IMR 4895, or 50 grs. of IMR-4064 or Olin's W-W748. Accurate Arms 2015BR and 2495BR are also suitable using the charges recommended by them. In commercial brass these powder charges intended for
GI cases may be increased 1 grain. These are fine match loads for offhand and 200 rapid in the M1 using the 150-gr. Sierra MatchKing or the new 155-gr. "Palma" bullets.
Prior to the introduction of the 168-gr. Sierra MatchKing, the 125-gr. spitzer was favored for 200-yd. offhand and sitting rapid-fire stages of the National Match Course. These are highly accurate, and ideal for the reduced scale courses for use by junior shooters, to reduce costs and minimize recoil. The charges for 150-gr. bullets, listed above, function the M1 rifle and are accurate. They also make dandy woodchuck loads.
WITH 168-SIERRA OR PULLED GI MATCH BULLETS a charge of 46 grs. of 4895; or 48 grs. of 4064 or 748 approximates .30-'06 M72 match ammunition (2640 +/- 30 f.p.s). With 168-gr. match bullets, these charges may be increased 1 grain, but if the 180-gr. Sierra MatchKing is used (a GREAT 600-yd. bullet for the M1) they should be REDUCED the same amount. I do not recommend slower powders or heavier bullets for the M1, because heavier charges of slower
powders operate the mechanism with more force than service ammunition, and may damage the operating rod or other parts.
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