timshufflin
09-07-2012, 06:14 AM
I see threads like this from time to time http://forums.thecmp.org/showthread.php?t=84844
I encourage people to investigate most everything on their own but in this case, I encourage folks to listen to me a bit.
A couple of myths to dispel
I need to adjust my Schuster screw for every ammo I use
Well, yes and no. One thing that is a key indicator in either the standard Garand, tanker, or Mini-G is ejection pattern. If your brass is being tossed at 1:30 all the way down to 5:00, you have no worries. If you're tossing brass at the target, 1:00 to 11:00, you have very fast bolt/oprod speed. In fact, your oprod speed is so fast that it may be moving faster than the rounds in the rifle can be pushed up by the follower. People often think their rifle needs a new oprod spring when this happens, you do NOT, you need to slow down your rifle.
I'm tossing brass at 5:00, I need a new oprod spring
This is hogwash! If your Garand, any Garand, is running fine and throwing brass at 5:00, you are shooting the perfect balance of gas pressure where the bolt speed is just fast enough to cycle the rifle. This is the most Garand friendly cyclic speed you can have. Yes, you may have a worn or leaky gas system in this scenario but your oprod spring is actually FINE. In fact, your oprod spring is probably on the strong side if you are not venting gas.
What's the problem with the ported type gas screw?
Simply put, in shorter Garands, ported screws may not decrease the pressure enough for the rifle to operate properly. How do I know this? I did not run a test using any gauge, I actually shot the snot out of various Mini-G's and Tankers that had the ported screw. These shorter rifles have less oprod spring, they just don't have the room to stack the amount of oprod spring that a full size Garand does. Add to that a lighter oprod and you have a FASTER oprod speed. In case you're wondering, this has NOTHING to do with the bolt unlock timing, muzzle length does, but that's another subject.
So we have a ported gas screw, pushing a lighter oprod, with a shorter oprod spring, most of the time the oprod will be very very fast. So fast that with the ported screw, there is not enough gas pressure relief to slow it down. The result is a bolt cycling so fast that it either goes over the top of the next round before the follower can push it up or it trys to slice the next round in half because it has not fully popped up in the follower area. Of course the worst part of this is empty cases flying at noon putting excessive wear on your rifle.
I can actually make a Mini-G or Tanker Garand that runs perfectly fine with a gas piston of .522! I can do this because with the same size barrel gas port as a standard Garand, I can push a lighter oprod with a shorter spring much easier than a full size Garand can.
The bottom line, I do NOT recommend the ported type gas screws in the Mini-G or Tanker type Garands as a silver bullet cure all, they may not even allow the rifle to work. I don't care what any mathematical testing on one rifle might show, I don't care what any such test shows on even 5 rifles. My experience goes much deeper than this, I've run at least a dozen different Garand variations with multiple types of gas set ups. I've run Garands with different barrel lengths, different muzzle lengths, different gas port sizes, different gas piston sizes, different oprod spring set ups, different ammunitions, and different extractor types, the ported type gas screw can NOT overcome all these scenarios, a Schuster CAN.
I encourage people to investigate most everything on their own but in this case, I encourage folks to listen to me a bit.
A couple of myths to dispel
I need to adjust my Schuster screw for every ammo I use
Well, yes and no. One thing that is a key indicator in either the standard Garand, tanker, or Mini-G is ejection pattern. If your brass is being tossed at 1:30 all the way down to 5:00, you have no worries. If you're tossing brass at the target, 1:00 to 11:00, you have very fast bolt/oprod speed. In fact, your oprod speed is so fast that it may be moving faster than the rounds in the rifle can be pushed up by the follower. People often think their rifle needs a new oprod spring when this happens, you do NOT, you need to slow down your rifle.
I'm tossing brass at 5:00, I need a new oprod spring
This is hogwash! If your Garand, any Garand, is running fine and throwing brass at 5:00, you are shooting the perfect balance of gas pressure where the bolt speed is just fast enough to cycle the rifle. This is the most Garand friendly cyclic speed you can have. Yes, you may have a worn or leaky gas system in this scenario but your oprod spring is actually FINE. In fact, your oprod spring is probably on the strong side if you are not venting gas.
What's the problem with the ported type gas screw?
Simply put, in shorter Garands, ported screws may not decrease the pressure enough for the rifle to operate properly. How do I know this? I did not run a test using any gauge, I actually shot the snot out of various Mini-G's and Tankers that had the ported screw. These shorter rifles have less oprod spring, they just don't have the room to stack the amount of oprod spring that a full size Garand does. Add to that a lighter oprod and you have a FASTER oprod speed. In case you're wondering, this has NOTHING to do with the bolt unlock timing, muzzle length does, but that's another subject.
So we have a ported gas screw, pushing a lighter oprod, with a shorter oprod spring, most of the time the oprod will be very very fast. So fast that with the ported screw, there is not enough gas pressure relief to slow it down. The result is a bolt cycling so fast that it either goes over the top of the next round before the follower can push it up or it trys to slice the next round in half because it has not fully popped up in the follower area. Of course the worst part of this is empty cases flying at noon putting excessive wear on your rifle.
I can actually make a Mini-G or Tanker Garand that runs perfectly fine with a gas piston of .522! I can do this because with the same size barrel gas port as a standard Garand, I can push a lighter oprod with a shorter spring much easier than a full size Garand can.
The bottom line, I do NOT recommend the ported type gas screws in the Mini-G or Tanker type Garands as a silver bullet cure all, they may not even allow the rifle to work. I don't care what any mathematical testing on one rifle might show, I don't care what any such test shows on even 5 rifles. My experience goes much deeper than this, I've run at least a dozen different Garand variations with multiple types of gas set ups. I've run Garands with different barrel lengths, different muzzle lengths, different gas port sizes, different gas piston sizes, different oprod spring set ups, different ammunitions, and different extractor types, the ported type gas screw can NOT overcome all these scenarios, a Schuster CAN.