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Thread: M1 Garand gas port size?

  1. #1
    Sponsor ADfields's Avatar
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    Default M1 Garand gas port size?

    I have an M1 I just inherited from my Dad that needs a barrel since he blew the old one to heck with water damaged ammo. I can get pull off barrels for around $40 but I donít like my odds of a safe head space just slapping a used 30-06 pipe on it. So I priced new and after I picked my cigar up from the floor decided I wonít be doing that any time soon.

    So the tight wad in me (which I also got from Dad) got to thinking what about getting a 308 barrel and cutting a correct head spaced 30-06 chamber in it. Now, I know the gas port on a 308 is not the same size so I need to know if its smaller or larger than on the 30-06?? If 308 is smaller then I can just punch it out and be in business.

    I have 3 M1s here but all 30-06 and I canít find the gas port size on the web so where are the M1 gurus that know? Is the higher pressure 308 port smaller like I think guys???
    Andy
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    Did you check with www.ODCMP.com also give these fellas a look www.mccannindustries.com. The cmp site also has a forum and there are barrels that you need on there.
    dabigmoose

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    Sponsor ADfields's Avatar
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    I was hoping someone here would know but if not I may need to ask over at the CMP forum, someone there is sure to know.
    Andy
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    Member gunbugs's Avatar
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    Douglas makes new garand 4 groove barrels at a reasonable price. Short chambered for 30-06. you'll have to cut your rear hand guard as they are full round contour at the rear. I've installed a few over the years and they're good shooters. Also have a few GI takeoffs laying around if you are interested. PM me for details.

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    Quote Originally Posted by ADfields View Post
    I have an M1 I just inherited from my Dad that needs a barrel since he blew the old one to heck with water damaged ammo. I can get pull off barrels for around $40 but I donít like my odds of a safe head space just slapping a used 30-06 pipe on it. So I priced new and after I picked my cigar up from the floor decided I wonít be doing that any time soon.

    So the tight wad in me (which I also got from Dad) got to thinking what about getting a 308 barrel and cutting a correct head spaced 30-06 chamber in it. Now, I know the gas port on a 308 is not the same size so I need to know if its smaller or larger than on the 30-06?? If 308 is smaller then I can just punch it out and be in business.

    I have 3 M1s here but all 30-06 and I canít find the gas port size on the web so where are the M1 gurus that know? Is the higher pressure 308 port smaller like I think guys???
    I don't remember the size of the Garand port and don't know if a straight conversion to 308 with no barrel length change (like the Navy guns) would need a port size change. I will give a educated, scientific guess and say no. Both use the same burn rate of powder (4895,4064, RL-15) and the 30-06 Garand loaded correctly gives 14,500 psi at the port. How would a 308 be so different to require a port size change. I don't know. You are thinking along the right lines though. The world famous BM-59 with shortened barrel, in 308, is the same gas system so you could check on those changes to port size, also the different barrel length for the BM-59. I know the Beretta system did work well but I have no dimensions. Also, you should consider keeping a Garand in the original caliber, that's cool enough, right?
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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    Quote Originally Posted by Murphy View Post
    I don't remember the size of the Garand port and don't know if a straight conversion to 308 with no barrel length change (like the Navy guns) would need a port size change. I will give a educated, scientific guess and say no. Both use the same burn rate of powder (4895,4064, RL-15) and the 30-06 Garand loaded correctly gives 14,500 psi at the port. How would a 308 be so different to require a port size change. I don't know. You are thinking along the right lines though. The world famous BM-59 with shortened barrel, in 308, is the same gas system so you could check on those changes to port size, also the different barrel length for the BM-59. I know the Beretta system did work well but I have no dimensions. Also, you should consider keeping a Garand in the original caliber, that's cool enough, right?
    Hi Murphy
    You been on the road again?

    It will stay 30-06 for sure, it always was, to me 308 says M1A not Garand. I was thinking of cutting the 308 barrel to a 30-06 so I would for sure get a barrel to head space the first time. I don't know why the port is different other than the 308 round runs at a higher pressure than 06. According to the new barrel makers I have considered they must know the caliber even on unchambered orders due to 06 and 308 taking different port sizes. If they don’t cut a chamber they still need to know since all the muzzle work is done in one CNC operation including the port cut a port on an M1 they say. That’s the only reason I ever even thought about the port size, I had assumed they were the same.

    What I was worried with a used barrel about is head space but I contacted Numrich and they say I can return all I want if I pay actual shipping. So feel better that way knowing if I get one with too much head space I get to spin again. I ordered a pull off 30-06 last Friday so we will see.
    Andy
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    Member GD Yankee's Avatar
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    Another option with the gas port issue, if you actually have issues with it, is to put a "Schuster" adjustable gas plug on it. MidwayUSA sells them for about 25 bucks I think. I've got one on my Garand and it is a great piece of gear.

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    Default Garand replacement barrels

    There are pull off barrels available, most often there is a very good reason that they've been pulled off, mostly muzzle wear, throat wear, or damage. Unless you're doing a full-on restoration, and need a specific barrel date/manufacturer, it's tough to justify the exense of one of these.
    Brand new arsenal barrels surface from time to time, but get ready to release the moths from your wallet for one of these.
    .308, .35 Whelen, and other '06 based rounds are entirely possible on the Garand, especially if you go ahead and start out with the Schuster in the gas cylinder.
    .308 conversion is far and away the most popular conversion, and at most, may require a block at the front of the magazine well to keep the shorter rounds from moving around. The shorter round feeds, and functions just fine, and will almost always give better accuracy.
    Installation can be a bit tricky, and may be best left to someone who's equipped with the 'right' barrel and receiver wrenches, knows how to index the barrel to the receiver, and (preferably) has a pull-through reamer appropriate for the job.......

    http://www.odcmp.com/Links.htm

    http://estore.odcmp.com/store/catalo...4=&note5=&max=

    http://www.kriegerbarrels.com/M1Gara...246-wp3393.htm

    http://www.fulton-armory.com/

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    Quote Originally Posted by Darreld Walton View Post
    There are pull off barrels available, most often there is a very good reason that they've been pulled off, mostly muzzle wear, throat wear, or damage. Unless you're doing a full-on restoration, and need a specific barrel date/manufacturer, it's tough to justify the exense of one of these.
    Brand new arsenal barrels surface from time to time, but get ready to release the moths from your wallet for one of these.
    .308, .35 Whelen, and other '06 based rounds are entirely possible on the Garand, especially if you go ahead and start out with the Schuster in the gas cylinder.
    .308 conversion is far and away the most popular conversion, and at most, may require a block at the front of the magazine well to keep the shorter rounds from moving around. The shorter round feeds, and functions just fine, and will almost always give better accuracy.
    Installation can be a bit tricky, and may be best left to someone who's equipped with the 'right' barrel and receiver wrenches, knows how to index the barrel to the receiver, and (preferably) has a pull-through reamer appropriate for the job.......

    http://www.odcmp.com/Links.htm

    http://estore.odcmp.com/store/catalo...4=&note5=&max=

    http://www.kriegerbarrels.com/M1Gara...246-wp3393.htm

    http://www.fulton-armory.com/
    I don't want to convert it, this one was my Dad's and I got it when he died last month. When he got it in the 80’s I went with him to G&J Sales and picked up my first M1 the same day. The gun exploded in Dad’s hands due to water damaged surplus ammo about a month later and I just want to make it functional, whole, and safe. I have all the stuff to do about anything to it, just had an obscure question on port size is all.
    Andy
    On the web= C-lazy-F.co
    Email= Andy@C-lazy-F.co
    Call/Text 602-315-2406
    Phoenix Arizona

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