I'm gonna cut it..!

Discussion in 'Gunsmithing Forum' started by ANGRYcanary, Dec 6, 2011.

  1. ANGRYcanary

    ANGRYcanary New Member

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    I cut my 20" barrel to 16"... The gas port is now 3.25" inches from the muzzle (I already ordered a 20" Varmint for the replacement, incase this goes horribly wrong.) Now, I need to know what are the sizes you all may have heard the gas port needs to be opened up to (I've heard 0.05 to .110), and, what are the spring changes that need to be done if any.

    I know you guys know this.
    Thanks all !!!

    :cool:
     
  2. danf_fl

    danf_fl Retired Supporter

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    Knock, Knock.
    Who's there?
    BATFE. Do you have the NFA cert for cutting the barrel so short?
    It's 16 inches!
    According to my tape measure, it's 15.9996 inches.

    (When you cut, give at least 1/4" so no mistake can be made)
     
    Last edited: Dec 6, 2011

  3. HOSSFLY

    HOSSFLY New Member

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    Wat gun are you talking about :confused:
    16" on rifle PLUS 1/4"
    18" on shotgun PLUS 1/4"
     
  4. ANGRYcanary

    ANGRYcanary New Member

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    Hey Hoss, How's it goin sir..?
    It's the RRA LAR-8. It was 20", Now it's 16 1/4"
    Already checked with the local L.E., and don't need a "hobbyist" gunsmith cert.,
    dan, you scared me for a minute there..! Whew..! Hahaha.
     

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  5. HOSSFLY

    HOSSFLY New Member

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    Sorry-
    You good on a 16 1/4" barrel on that puppy :cool:
     
  6. ANGRYcanary

    ANGRYcanary New Member

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    Cool, cool sir, and thank you..
     
  7. neilage66

    neilage66 New Member

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    One question:

    Hack saw, cutting torch or lathe? ;):D
     
  8. HOSSFLY

    HOSSFLY New Member

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    Torch is quicker- Boolits should knock out the burrs :p
     
  9. neilage66

    neilage66 New Member

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    Yessir, I heard tell of the deburring boolits my own self. :D
     
  10. ANGRYcanary

    ANGRYcanary New Member

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    I wrapped the barrel with paper towels, then I took a piece of angle iron and strapped it on with an airplane/hose clamp for a guide, then used a sawzall then used a fine tooth file, then 320 grit sandpaper and my thumb, then green scotch brite then red scotch brite. I'm workin up a photo now..
    :D
     

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    Last edited: Dec 6, 2011
  11. Sniper03

    Sniper03 Supporting Member Supporter

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    Angry,

    First of all I certainly hope it was not a chrome lined barrel!!
    Secondly the rule of thumb concerning the gas port size is the longer the barrel the larger the gas port size. You should be fine as far as operation. The logic in this is that you did not actually shorten the distance between the chamber and the gas port. Even though the gas port is closer to the muzzle that should not change it that much. You will just have to shoot it to find out if the reduction of bore after the gas port caused any problems with reliability function. All rifles are like individuals and have their own personalities. Also the rounds you are shooting through it could also determin the difference between a problem and no problem at all. Military Ammunition is Hotter than most Commercial! "Higher Pressures" Moral of the story if it ain't broke don't fix it. Let me know what you find out! :)

    03
     
  12. ANGRYcanary

    ANGRYcanary New Member

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    I saw that RRA actually cryogenically treats the barrels so I didn't want to change the physics of the barrel metallurgy...
     
  13. ANGRYcanary

    ANGRYcanary New Member

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    Thanks Sniper... I was just about to start drilling too.. I'll shoot it first..! Oh, no the barrel wasn't chrome lined, I checked that out already too, thanks for the warning though..! Damn, the Fiance just got home... Good thing I wasn't drilling yet..! I'll Take it out this Saturday guys, I'll post the results up here... Thanks again guys..!
     

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  14. Wilder

    Wilder New Member

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    Looks like you did a pretty good job on the muzzle, but I would make one suggestion. Use a piloted reamer to clean up the crown right at the edge of the bore. That will make it so the gas escapes behind the bullet uniformly. If it escapes a little on one spot before another, the gas can kick the bullet off it's axis and ruin your accuracy. Brownells.com should have one you can do by hand, or if you have access to a lathe that would be better as you can use a live center on the tail stock to align the bore to the piloted reamer. I usually try to make as small a cut as I can, about 1/16 of an inch . Just make sure there are no chatter marks (chatter is vibration in the cutting tool leaving a rough bumpy finish). It is also an inexpensive thing for a gunsmith to do if you don't expect to need the reamer again, as they can be pretty expensive for good ones. Also a little cold blue (i.e. oxpho blue) will get rid of the shiny muzzle for you.

    Oxpho-Blue OXPHO-BLUE® - Brownells
    crown tool Brownells Search : Gunsmith Tools & Supplies : Barrel Blanks & Tools : Barrel Chamfering Tool Kits - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools - BROWNELLS
     
  15. ANGRYcanary

    ANGRYcanary New Member

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    Thanx Wilder..! I Appreciate it. :cool: