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Thread: M1 with adjustable gas plug

  1. #1
    Boolit Master
    woodbutcher's Avatar
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    M1 with adjustable gas plug

    I know that 4831 is not recommended for the M1 due to possibly damaging the op rod.
    However,would it be possible to use 4831 in conjunction with the adjustable gas plug to prevent op rod damage?Have been curious about this for awhile.
    Thanks for any responses and the time to do so.
    Good luck.Have fun.Be safe.
    Leo
    People never lie so much as after a hunt,during a war,or before an election.
    Otto von Bismarck

  2. #2
    Boolit Master
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    The danger of op rod damage has to do with the force of the gas pressure being too high (hitting the op rod with too much pressure). If you open the gas plug wide open the pressure will go out through the valve without hitting the op rod-- and there will be no problem. Of course, the M1 will not cycle either. FWIW I always operate my M1 this way, and simply pull back the bolt after each shot, then let it close on its own using the spring. This way I can better control where the hot brass if going (a good thing on a crowded range).
    Hick: Iron sights!

  3. #3
    Boolit Master Jack Stanley's Avatar
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    It would seem if you control how much gas hits the piston you could control how the rod is moved .

    Jack
    Buy it cheap and stack it deep , you may need it !

    Black Rifles Matter

  4. #4
    Boolit Master
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    Gentlemen.Thank you for your time to read and reply.Back when I was reloading,I had a load with H4831 that was a real tack driver.58grns,150 gr Sierra spitzer,1964 LC match brass,cci lrp.Oal was 64 LC match round.A friend that shot on the NG rifle team wanted some to shoot in a match,and I warned him that that load could kill his op rod.He said no problem as he had about 10 or 15 spares.Well he won the match.
    The groups that I was getting at 100 yds was 3/8th in for 3 shots and less than 3/4th in for a group of 20 rounds off of a sandbag.My rifle was a Sears Mod 53 with a Weaver K4 with duplex cross hairs.He saw me shoot the groups,and that was why he wanted some for the match.
    Good luck.Have fun.Be safe.
    Leo
    People never lie so much as after a hunt,during a war,or before an election.
    Otto von Bismarck

  5. #5
    Boolit Grand Master

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    I made ported plugs for my M1As. they did several things for me. 1) they did help to tone ejection down. With the one port ejection was at 1:00-2:00 and about 2 ft in distance. just in front of my shooting stool. With a bigger port the cases just dribbled out by my right elbow. 2) The impulse of the bolts hitting the end of travel was reduced. 3) accuracy could be tuned with the changing of plugs This showed more at 600yds than 200 and 300. My plug were home made. I drilled a .093 hole thru the plug then drilled and tapped to depth for a 10-32 set screw from the inside. I then drill 10-32 set screws with holes from .045-.065 in roughly .005 increments making an adjustable insert. It did soften functioning of the rifle depending on port size installed. I used a piece of 1/4" X1" brass flat stock and drilled 10-32 holes to hold and id the ports. It also held the allen wrench to change them. I then made an wrench for the port that held the ports in the handle and allen wrench in the side of the handle.
    I also use adjustable gas blocks on my AR match rifles to tone functioning down and tune. These are a needle valve type set up I made and require a open ended tube.

    Shuster manufacturing makes ported plugs in Toledo Ohio.
    Setting one up is a little work as I started with biggest and worked down to desired functioning then tuned with one either side during 600 yd practice nights.

    It should help with battering and bending op rods but may not completely alieviate the problem

  6. #6
    Boolit Grand Master

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    As a point of difference. Theported plugs on the M1A and garand bleed off extra pressure. the port remains and allows the same amount of gas and pressure to pass thru. The port bleeds extra off. On the AR set up the needle valve limits gas and pressure entering the tube by closing off the port hole in a small amount. Big difference here in how they work. On the M1a and garand with the moving pistons closing the port off isn't an option. The M1A does limit pressure thru the timing as gas pushes the piston back the port hole and hole in the piston are closed of to each other.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check