This past summer I bought my first Garandicon and had the same concerns. I had been reading on various forums and heard about "Adjustable Gas Plugs" aka adjustable gas cylinder lock screws. There are two both available from Brownells, Shuster(sp.) and McCann(sp.).

I ended up with the Shuster. The shuster uses an allen headed plug and locking screw that can be adjusted easily if you use different loads. The McCann uses a set of perforated disks that that are changed to find the right amount of gas to operate the action, I think this would be good if one type of ammo was used.

I have been reloading for a couple of years and hunt. I started out with factory loads to get a base line with the Shuster plug. There is no one setting and so you just screw the plug in until the action works.

I use 180 gr Bronze Tip and Core-locked Remington factory ammo, no problems.
For reloding I'm settling on some flavor of 180 gr. bullet and H4895 or IMR4064.