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Rifles, Reloading, Optics, Equipment
AR15/10 Rifles
308 win AR platform reloading question
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<blockquote data-quote="Toddxusmc" data-source="post: 1771631" data-attributes="member: 108726"><p>As RSMITHSR stated service rifle data mainly really only applies to the M1a/M1 Garand type rifles but not exclusively. The reason being is that class of rifle was designed for a port pressure of 12K psi to run the action. Anything much higher and you start bending and breaking op rods. The slower the powder the longer the pressure curve, this leads to higher port pressures, heavier bullets typically need a slower burning powder to manage chamber pressure and maximize velocity. While not as big an issue on the AR platform, you can still overgas and damage the action. Therefore you may want to go to an adjustable gas block, with which you can shoot pretty much any loading you wish. You should be able to load a 190SMK to magazine length with no problem. In my M1a I run a BERGER 190 vld with Win 760. I have an adjustable gas plug and a Sadlak grooved piston. While I would never shoot this from an un modified M1a, with the adjustable gas plug I can without worry of damage, I open it up completely and adjust until the action just cycles reliably.</p><p>If you don't plan on running an adjustable block, you can call the mfg and see what their port specs are, they should also be able to give you a recommended bullet weight and load parameter(although you may void your warranty as no mfg recommends handloads). Another indication would be the caliber stamped on the barrel, if it's 7.62x51 you might want to stay with service rifle data; if it's stamped .308 you should be ok with any load for a .308. Also when loading keep in mind that brass thickness and internal capacity can differ between headstamp and mil vs commercial brass.</p></blockquote><p></p>
[QUOTE="Toddxusmc, post: 1771631, member: 108726"] As RSMITHSR stated service rifle data mainly really only applies to the M1a/M1 Garand type rifles but not exclusively. The reason being is that class of rifle was designed for a port pressure of 12K psi to run the action. Anything much higher and you start bending and breaking op rods. The slower the powder the longer the pressure curve, this leads to higher port pressures, heavier bullets typically need a slower burning powder to manage chamber pressure and maximize velocity. While not as big an issue on the AR platform, you can still overgas and damage the action. Therefore you may want to go to an adjustable gas block, with which you can shoot pretty much any loading you wish. You should be able to load a 190SMK to magazine length with no problem. In my M1a I run a BERGER 190 vld with Win 760. I have an adjustable gas plug and a Sadlak grooved piston. While I would never shoot this from an un modified M1a, with the adjustable gas plug I can without worry of damage, I open it up completely and adjust until the action just cycles reliably. If you don’t plan on running an adjustable block, you can call the mfg and see what their port specs are, they should also be able to give you a recommended bullet weight and load parameter(although you may void your warranty as no mfg recommends handloads). Another indication would be the caliber stamped on the barrel, if it’s 7.62x51 you might want to stay with service rifle data; if it’s stamped .308 you should be ok with any load for a .308. Also when loading keep in mind that brass thickness and internal capacity can differ between headstamp and mil vs commercial brass. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
AR15/10 Rifles
308 win AR platform reloading question
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