.30-06 M72 Match analog load using Varget and Sierra #2275

[hkp7fan]

I spent today at the range with a chronograph testing handloads for my M1 Garand. I finally have a handload that duplicates military M72 Match ammunition:

Caliber: .30-06
Case: FA-61 Match
Bullet: Sierra 175 gr. HPBT #2275
Powder: 48.5 gr. Hodgdon Varget
Primer: Winchester Large Rifle
Cartridge Overall Length: 3.330"

This load chronographed at 2697 fps average velocity with an SD of 14.03. Since the target velocity was 2700 fps, I'd call it "spot on". It also happened to produce the smallest group and the highest score of the eight loads I tested (including some 1968-vintage M72).

I've been meaning to develop this load for a long time, as I am almost out of surplus M72. I would have loved to have simply found the load someplace, but I searched high and low and nobody had one listed for this bullet. Everybody seems to want to use 4895 or 4064 for their M1 Garand loads. But I love Varget, so this was a worthwhile exercise. Now people can find my load and use it if they choose.

Fair warning: There is a lot of conflicting data out there. Depending on which loading manual you read, this load may exceed the maximum recommended. But I found enough information to make me comfortable with it. Plus I'm using a McCann adjustable gas cylinder lock screw, so any extra gas just vents.

It was a beautiful day, and an awesome way to spend the last day of 2013.

Happy New Year!

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[hkp7fan]

Regarding velocity measurements:

I recently had a conversation with an engineer/ballistician who was involved in designing the new Navy sniper ammunition, which uses the 175 gr. Sierra HPBT bullet. (As an aside, the new MK 316 Mod O (7.62 Special Ball, Long Range) velocity is 2580 fps at 78 feet from the muzzle (22" bbl, same as an M1A), and they've achieved .75 MOA accuracy with it).

He told me something that I never knew before.

For obscure historical reasons involving the type of chronograph equipment used decades and decades ago, muzzle velocities used in military ammunition specifications are measured at 78 ft. from the muzzle. SAAMI specs, on the other hand, use velocities as measured 15 ft. from muzzle. I talked to a Sierra technician, and he confirmed that their ballistics software is based on measurements taken 15 ft. from the muzzle.

So you have to do the math for the particular bullet (taking into account the weight and ballistic coefficient) to translate between the two.

This solved the mystery for me about why the velocity printed on the box for M72 Match ammunition is 2640 fps. That is measured 78 ft. from the muzzle, so it would be higher if measured at 15 ft. using the SAAMI protocol.

He gave me a rough rule of thumb they use to predict velocity loss. I can't find my notes from that conversation right now so I don't want to try to repeat it, but I did the math at the time and came up with something close to 2700 fps as the muzzle velocity I would try for on the range with my chronograph at 15 ft. This turned out to be the most accurate load at 100 yards, the range I was shooting at over the chronograph. I can't speak to how it will perform at longer distances, as I haven't tried it yet. But I feel confident that this is close to the M72 Match round. In any case, it will work for me.

I did clock my 1968 vintage M72 Match ammo at 2620 fps yesterday. Since it was designed to be going 2640 fps at 78 ft. from the muzzle, it is clear that it has lost some power over the 40 years since it was manufactured. So unless you are just trying to duplicate the exact performance of the old ammunition you have been using, I think it's more desirable to work from the military specification. See TM 43-0001-27 - Army Ammunition Data Sheets, c15, 29 Mar 2013 for complete specifications.

FWIW, the Sierra ballistics software says that you could have a muzzle velocity as low as 2350 fps and still be supersonic at 1000 yards. I had the additional objective of finding a load in which I could substitute the Sierra #2160 180 gr. GameKing to use for hunting, and wanted to find the maximum safe velocity to ensure good terminal bullet performance.

In the end I think it boils down to what's most accurate in your own rifle for your own purposes.

Happy shooting!

[WarPig1976]

An old timer at my club uses this exact load, don't know seating depth, and achieved sub MOA with a bone stock 03A3 at 100yds. One day when he and I where the only ones there shooting for score I signed his target as a witness, he shot a 100. I don't use it because those bullets are expensive and we shot for bragging rights not money or a trophy. You won't get any argument out of me over this load....

[hkp7fan]

The TM says that the C.O.L. should be 3.340". I determined mine in part by measuring the ammunition from two different batches of M72 (FA-61 and LC-67). Both were consistently 3.330". I also looked at a large amount of load data for the Sierra #2275 and this length was often listed as the recommended C.O.L. That's why I chose to go with it rather than the number in the TM.