Safe Ammo

[Interlake]

That appears to lay it all out. So with my uncut op rod and Shuster plug, I should be safe to use any non-high power loads. Thank you for everyones input.

[Wineman]

According to Hatcher's Notebook the M2 was designed to replicate the M1906 round for all the reasons that Sunray described. The .30 M1 was the result of WW1 experience where the range of the M1903 and machine guns was not as far as advertised. The heavier bullets in the French Balle D and British MK VII carried further and were better for defilade fire. Testing at the end of the war with Swiss bullets from GP-11 showed that a heavier bullet was needed to get more range. To keep pressure the same, the velocity was reduced to 2,640 fps with the 172 grain bullet (all velocities were measured at 78' from the muzzle). The M2 was 2,800 fps, 100 fps faster than the M1906's 2,700 fps from the beginning. AP was 2,775 fps so pretty close to M2.

There is an interesting article on M1 Garand Ammunition and the Ported Gas Plug While not a ballistics lab, is shows a nice picture of how the port pressure is affected by different ammo types. The only op rod damage I have personal experience with is the tab at the rear wearing and the rod coming off the track when fired. Not sure why this happened, it was a CMP gun and only fired M2 ammo.

I stick with ammo that either says M1 Garand safe or make my own with powders in the burn range of IMR 4895 (my favorite is IMR 4064 but it meters like logs) and 150-175 grain bullets.

Dave

[Sunray]

"...safe to use any non-high power loads..." Pretty much. No Hornady Superformance ammunition that used to called "Light Magnum" despite Hornady saying it's OK in semi-autos. Otherwise any 150 to 180 grain ammo will do.
"...my favorite is IMR4064..." Yep. It's far more accurate than either 4895.
"...the port pressure..." I think that's an internet invention too. When JC loaded to 125,000 PSI, there was no mention of port pressure. He was debunking critics, who were mostly advocates of the Johnson, who were saying the M1 wasn't strong enough.
Matching ballistics was likely more about logistics than anything else. There was no such thing as .30 M2 until 1940 anyway.
I don't think the Schuster plug is anything but marketing myself. Been shooting my Rifle without one for nearly 50 years now with no fuss.

[browningautorifle]

I don't think the Schuster plug is anything but marketing myself.

There's yet another statement that shows no actual knowledge of the M1 operation and certainly no knowledge of the Shuster or other venting gas cylinder lock screws. That statement is wrong.

[jond41403]

That appears to lay it all out. So with my uncut op rod and Shuster plug, I should be safe to use any non-high power loads. Thank you for everyones input.

Yes, that will work just fine but I would take BAR's advice and just get another op-rod to shoot with if you could afford to do so because of the uncut rods are prone to crack and are less common and are usually put on corrected rifles that predate the revision to cut them.jmo

[bml]

There's yet another statement that shows no actual knowledge of the M1 operation and certainly no knowledge of the Shuster or other venting gas cylinder lock screws. That statement is wrong.

Most people are not going to use 180+ gr bullets and slow powders so the various types of pressure reducing gas plugs are pretty useless for the average M1 owner. Before these gas plugs existed people were shooting whatever ammo they had. A M1 is a pretty durable rifle and when properly maintained would take a steady diet of heavy bullets and loads to damage it. Most 150 gr off the shelf ammo puts less energy into the op rod than the heaviest M2 ammo.

[browningautorifle]

Before these gas plugs existed people were shooting whatever ammo they had

Before the internet exploded with stories of M1s supposedly destroying op rods with sporting ammo we shot whatever came to hand. I know that to be fact. I never even heard of a part breaking. When the vented gas plugs came out I tried one and it eased up the ejection of cases and softened up the action without stoppages. That was forty years ago for me, parts are older now and have had more time to fatigue.

The OP asked about using a Shuster and a steady diet of the hottest ammo still won't do damage. Your brass will be closer after as well.