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125 grain load for M1 Garand
- Thread starter akinswi
- Start date
Marco Califo
New member
You can look up your load here. IMR4064 will do fine. Google the pressure range Garands are rated for (40k psi). Starting load will keep you in that range.
http://www.hodgdonreloading.com/data/rifle
http://www.hodgdonreloading.com/data/rifle
...pressure range Garands are rated for (40k psi).
Where the heck did you come up with that number? That's less than the 30/40 Krag. The pressure range for the M1 Garand is the same as any .30-06 (50k CUP/60k PSI), the only thing you've got to take into consideration is the port pressure. Too much and you'll bend your op rod.
Don
Not even then. The thing that affects the op-rod is the gas impulse (pressure times exposure to that pressure on the barrel side of the gas port). For several common Garand powders, like 4895 and 4064, that impulse actually gets smaller as you pass the medium load range and head toward maximum because bullet velocity is increasing faster than muzzle pressure in that range. A lot of folks thinking their mild loads are Garand-friendly are actually driving the op-rod as hard as that particular powder can do it. They just assume the op-rod will be given an easier time by their lower load, but the measurements say otherwise. Garand Gear engineer Chris C. had a great plot of gas cylinder pressure measurements done with IMR8208XBR powder, which is one for which that decline in gas impulse with increased charge weight past the middle range is large.
Just stick with powders for which listed maximum charges are under 53 grains with 150-grain bullets, and you will be fine.
Just stick with powders for which listed maximum charges are under 53 grains with 150-grain bullets, and you will be fine.
Yep. Those all fall into line.
For the 125-grain bullet that the OP is interested in, his 4064 at Hodgdon's listed starting load of 53 grains should be a good starting point. I calculate the gas port impulse at about 2/3 that for a 175-grain SMK over 48 grains of the same powder, so the op-rod should be happy with it. The CCI #34 Military-sensitivity spec primers may make it go a little faster, so I would use a chronograph just to be sure you don't exceed the maximum load velocity of 3334 fps listed by Hodgdon. A load of 56.5 grains has a fraction lower gas port impulse than the starting load, so the op-rod should be happy over the whole range.
For the 125-grain bullet that the OP is interested in, his 4064 at Hodgdon's listed starting load of 53 grains should be a good starting point. I calculate the gas port impulse at about 2/3 that for a 175-grain SMK over 48 grains of the same powder, so the op-rod should be happy with it. The CCI #34 Military-sensitivity spec primers may make it go a little faster, so I would use a chronograph just to be sure you don't exceed the maximum load velocity of 3334 fps listed by Hodgdon. A load of 56.5 grains has a fraction lower gas port impulse than the starting load, so the op-rod should be happy over the whole range.
I show you should get peak pressures of about 37,700, 2880 fps at 15 feet from the muzzle, and 39,900 psi and 2945 fps, both measured when the powder is back over the flash hole. The peak pressure and velocity will be lower when the powder is thrown forward, as the Garand tends to do. But test barrel ammunition is always manipulated to put the powder over the flash hole, so those are the numbers I can extrapolate from Hodgdon's data for their test barrel. The SAAMI spec pressure and velocity barrels used by Hodgdon in a universal receiver for testing are minimum chamber spec which will be tighter than your Garand has, in all likelihood, so your pressures and velocities are likely to be lower. It also applies to the lot of powder they developed the load with, and yours could be different in either direction. A chronograph would tell you with more certainty. If you find the powder burns dirty or incompletely (you find unburned grains in the bore) then low pressures are the cause.
If you follow Chris Long's optimum barrel time theory, that Hodgdon pressure barrel with 52.2 grains (about 45,300 psi and 3,080 fps) or with 55.3 grains (about 54,130 psi and 3266 fps at 15 feet from the muzzle) would be on Long's node positions ±2% of charge weight.
The light bullet lowers pressure significantly. If you prefer to run the loads slower you will find a faster powder like 3031 burns better and uses lower charge weights to save some money. I also like VV N135 for better case fill.
Good luck with the tests!
If you follow Chris Long's optimum barrel time theory, that Hodgdon pressure barrel with 52.2 grains (about 45,300 psi and 3,080 fps) or with 55.3 grains (about 54,130 psi and 3266 fps at 15 feet from the muzzle) would be on Long's node positions ±2% of charge weight.
The light bullet lowers pressure significantly. If you prefer to run the loads slower you will find a faster powder like 3031 burns better and uses lower charge weights to save some money. I also like VV N135 for better case fill.
Good luck with the tests!
I went all the way up to about 52 grains. I will check for any unburnt powder. Im interested too see how they group, sierra claims that their polymer tip match kings have better “bc” than the traditional SMKs. Our gun club has only range out to 200yds so I wanted to use A flat based bullet for better accuracy we have our annual military firearms match that i plan on winning but have to tweak the load for this M1. Your info is also useful