New Garand owner here. Been doing some reading up on the rifles, but just want to clarify which ammo should I buy the adjustable gas plugs for? If I buy Prvi 150gr stuff am I okay or is this ammo still too hot? Any help would be needed, as I'd like to buy some ammo and shoot it this week.

I've used the ppu garand load without problem. Now I just load my own.

You don't need that adjustable gimmick..

Grease your rifle properly..make sure your oprod spring is in spec and shoot away.

CMP says 180gr or less is fine..and recent tests show even 220s are fine.

The garand is more robust than the internet let's on.

Good to know. Definitely had a slight worry about what to buy as I didn't want to damage something. But looking forward to putting rounds down range with it.

I would not shoot that in my rifle.  

Read this:  

https://www.garandgear.com/m1-garand-ammunition  

I prefer a cautious route with my rifles.  
The other poster is grossly simplifying and exaggerating what can be safely shot in an M1.

And it's not the internet that realized the short comings of the M1 Garand, Mr Garand himself did.

The way I see it, the M1 was overgassed to allow for reliable function in all climates, under adverse conditions, with ammo of varying quality and when a part broke Uncle Sam had bins upon bins of spare parts to make em like new.

None of these apply when I am punching holes in paper or soda cans. To me the Schuster makes a ton of sense. Even with M2 ball and other light loads. Less wear and tear on parts, light recoil impulse and a nice neat pile of brass to pick up.

I agree that the internet has created a cult of people overly concerned about the supposed delicate nature of these old war horses but given how expensive M1s have become, I see zero reason to stress test them unless you are using the rifle for some sort of serious purpose like hunting or self defense. YMMV

Nothing wrong with PPU 150grn..already been tested and found to be rather mild.

You can argue with opinions...or facts....

I prefer facts..

Privi 150 is good to go, IMO.  Never a problem in Garand or '03A3.

Hking

Just make sure you’re buy the PPU that is loaded for M1 Garand.  Works really well.  Much better quality than the Greek HXP floating around for inflated prices that so many people go nuts for.

Like said the Garand is no fragile flower.

Get a new oprod spring either NOS gi or new from Orion7. Properly lube it using high melt temp grease you only need enough to make it look wet if you can see color of grease you are using too much.

+2 don't trust the CMP on making sure you get a serviceable oprod spring . I have recvd too many with broken or totally shot springs.

With PPU's 'Garand-safe' .30-06 ammo, no adjustable gas plug is needed. Nor is one needed to shoot the over-priced, over-hyped, almost legendary HXP surplus '06. For such ammo, the USGI gas plug is fine.

Adj. plugs, like the one Schuster Mfg. makes, are good for if you're trying to tune a specific handload to your rifle, or if you're going to hunt with your M1 (many guys do) and intend to shoot one of the hotter '06 'hunting' loads topped with the heavy 180gn, 200gn, or 220gn .30-cal bullets.

Schuster's adj. plug will allow you to tune the ammo's specific bullet-weight and energy level to your rifle, so that it will cycle the action reliably but without risk of damage to the op rod or bolt, ... if that's a concern. Some folks believe it is; others don't.

Those who want to play it safe install an adj.plug for hunting season, and then swap it back out for the GI plug when they return to shooting the PPU stuff (or similar '06 ball ammo) in service rifle matches.

I've personally found that no adj. plug is needed for a Garand chambered in  .308/7.62, as the energy level of that ammo is inherently 'Garand-safe.' (I own three M1s in that chambering).

Long term the only way to feed an M1 with any frequency is to reload there are tons of Garand safe loading data out there, and you can reload 3 to 4 rounds for the price of a single factory round