The Port pressure adjustment ~1 inch from end of Barrel
CAN NOT AFFECT MUCH, DUE TO THE SHORT DWELL TIME OF PRESSURE.
The bullet is out of the bore Microseconds later... Gas bleed time is the amount of time available to bleed thru port before bullet clears muzzle ( a simple bleed non/cutoff port system).. Inertia/weight of Op rod and bolt are not simple items to change.
There will be some adjustment with a gas bleed...... but the rifle is not designed for other than service cartridges, and if you have a single wrong load sneak in, (or wrong bleed orfice in) Bent op rod or worse....
There is no need to shoot heavy bullets or slow powders in the Garand...
Barrel twist is not optimized for heavy bullets anyway.
If you carry a Garand Hunting, must be in good shape...
I know at 17 or so the thing got heavy... It did lighten up when I saw a deer....
Another reason for not using a Port bleed is... How do you know how fast a powder is in commercial ammo? They might change powder due to cost/availability. As long as Velocity is as stated, they are happy.. Garand might not be...
Best thing is to just reload with 3031 or so, and some decent 165-172 soft point spitzers.
The Mini 14 has a more modern mid barrel gas port, and an adjustment there allows something to actually happen.
Just like aftermarket recoil buffers for many guns (not all)....they cause more problems than they supposedly solve... A lot of guns have come in my shop and left with the add on buffer removed.. The customers did not realize that the malfunctions started exactly the same time they put the buffer in.. The ad said it was good, so it must not be that....
I get a kick out of the add on CHEAP plastic recoil buffers sold for Cetmes and HK rifles, which have a fully engineered, perfectly functioning multicomponent spring buffer system already built in.... Thier sales spiel says you will damage your rifle if you don't have a buffer....
I have a lot of experience with Short Barreled NFA AR15 M16 FAL HK... Shortening distance from gas port to muzzle (Even with FULLY adjustable Gas bleed systems) causes functioning problems. Opening up Port diameter to increase pressure comes at the cost of increased operating rod velocity, and the added wear and tear on extractor and other parts.
The Garand comes with the short distance standard...Changing the port timing/distance from muzzle is the best way to increase flexibility with ammunition. But the Garand is what it is.
I stand by Pimping. It is a 60+ year old design, tried and true, with some flaws, in no need of Modernization..
The Army spent $$$$$ trying to upgrade parts of it (Back when they actually knew how to design something...)
There are numerous simply made, screw on gizmos I could make and sell, but MY NAME will never be associated with a Snake Oil Product....