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Old 07-15-2006, 10:16 AM   #1
Join Date: Mar 2005
Posts: 49
Adjustable gas screws

Has anyone used one and what difference does it make on accuracy? I have heard that if you can adjust it so that the oprod does not start moving until after the bullet exits the barrel, you will see quite an improvement in group size.
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Old 07-15-2006, 11:06 AM   #2
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Location: ohio
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Yes, yes, and, yes.
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Old 07-15-2006, 01:31 PM   #3
Join Date: Oct 2004
Posts: 195
I used a Schusters plug for deer season shooting some commercial PMC soft points. Just some 150 grain stuff. My M1 really likes that ammo! Maybe tightened up my groups with the M2 Greek a small bit , but not anything spectacular. Seems to have softened the recoil of the M2 a little also. HTH
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Old 07-15-2006, 05:49 PM   #4
Join Date: Jul 2004
Posts: 371
I put a Schuster on my .308 Garand to fine tune the feed system a bit and the groups have gone down about an inch. I was shooting 4-5 inch groups at 100 yds and now am shooting 3-4 inch groups. I may try some 168 gr rounds some time in the future so it will be handy then.
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Old 07-23-2006, 06:31 PM   #5
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Join Date: May 2004
Location: outside Atlanta
Posts: 642
I tried the Schuster plug in my "Tanker" 308 project without obtaining the effect I was looking for. The brass from m80 ball was ejecting AK47 style 10 to 12 foot to the right front. My handloads with a moderate load were 6 foot to the right rear. I felt there was too much gas getting to the op-rod, probably from a slightly too large vent hole in the barrel. The Shuster plug had no effect on damping the brass ejection, even when adjusted fully out. I then tried a McCann adjustable plug and voila. It has 5 insert plugs ,each with a different size vent hole. The next to the largest hole provided the effect I wanted. Barely ejecting my moderate handloads , and ejecting m80 ball about 6 feet to the right rear. The 3rd largest vent plug kicks out brass only slightly father , and reliably ejects the clip , with moderate handloads. The pleasant suprise to me was that the groups of my moderate 168 SMK load and the groups from my lot of Port. M80 ball ( I think its really probably M59) are only about 2 inches in elevation from each other at 200 yards and same windage.. Back to the range next week with chronograph , but yesterdays testing was very encouraging. This rifle continues to amaze me. I'm seriously considering trying to talk Old Hook, into building me one more , in 30'06.
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Old 07-24-2006, 03:49 AM   #6
Join Date: Aug 2004
Posts: 444
I have used the McCann, but not the Schuster. I would think they are similar, a least bleeding off the gas.
Haven't noticed any difference in accuracy. I would definitely want one on my M1, especially if I were shooting the Greek ammo or commercial ammo.
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Old 07-24-2006, 05:51 PM   #7
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Join Date: May 2004
Location: outside Atlanta
Posts: 642
To make it a bit plainer. The Schuster plug changes the harmonics of the Barrel/op rod by increasing/decreasing the volume of the gas cylinder. It did not appear to effect the pressure enough to notice a change in ejection pattern,. The McCann plug vents gas out the end of the plug through holes drilled in an insert , inside the plug. It did cause a very noticible change in ejection pattern, and changed the groupings on paper. For the better. Will try to get chrono readings this weekend if weather permits.
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