Gas plugs and Garands

[Chevy Boy]

Hello all.

I've got an M1 Garand that the previous owner had rechambered in .308. I'd like to run commercial hunting loads (180 gr and up) through it, but I've heard tell you can't run ammo that hot through an M1 without busting the op rod.

It's been suggested I get a new gas plug.

Somebody else says if it's a .308 I don't need one. 

Don't know enough about shooting commercial loads through Garands to make a decision, any of y'all M1 owners out there want to weigh in on this it'd be much appreciated.

[High Noon]

Would imagine a 308 would have similar pressures to 30-06 and the risk would be the same.  However I am just guessing/assuming and haven't looked into it.  My Garands always have 30-06 made for M1s run through them - just to be safe. 

Have you tried researching or posting on the CMP forums?  I'm sure you can find an answer there.

[Bacarnal]

Chevy, For the most part, it's not that the ammo is "hot", it's that the heavier weight bullets are loaded with a slower powder.  This means that the peak pressure, instead of being around the middle of the barrel, it ends up being at around the gas port.  This causes battering of the op rod then everything down the action.  If you can find .308 loaded with a faster powder or specifically loaded for semi auto rifles (Remington used to do that because of their 700 series), you should be fine.  Either that or have handloads made. 
Another thing I've experienced with .308/7.62x51mm barrels is that the gas port usually needs to be larger.  Off hand from memory,  the gas port for the .30-06 barrel is .085-.095".  For my .308 barrels, the port needs to be .110-.120". 
Hope this helps.  Cheers, Bruce.