And, of course, there is always the adjustable gas nut as an option. These are made by McCann and Schuster.
Here's a link to McCann Industries -
http://www.mccannindustries.com/scope/parts.html
The idea is, you start with the nut adjusted wide open (Schuster) or with the largest orifice installed (McCann), then adjust smaller until the rifle's action cycles reliably. This is usually done with a single round, and a check to see if the action locked open correctly. If it will do this, and nothing else is wrong, it will probably feed properly from the clip.
You have to do this every time you change loads, but it will permit using other than military spec ammo in the Garand. (Within reason...)
I'm using 46 gr of Varget with 150gr FMJ bullets. Some have told me this is just fine without messing with an adjustable gas nut, but it isn't H4895 so I'm not taking any chances.
The important thing to realize, IMO, is that it isn't as simple as bullet weight. It's a pressure curve you have to worry about, so powder burn rate is also part of the problem. The adjustable gas nut is a mechanical solution that permits safe operation without actually knowing what the pressure curve is.