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Thread: Mini 14 to 300 blackout

  1. #1
    Boolit Master

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    Mini 14 to 300 blackout

    So the new barrel is on and the action will not cycle. Put in a larger gas port and still won't cycle. Got a new spring and it is longer than the one that is in it. Tried a light spring and action opens and ejects but will not feed ( not enough spring pressure). Any ideas? Trigger pull gauge shows about 5 pounds for the first 1" of travel to open.

  2. #2
    Boolit Master
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    Iirc that gun has a gas port at a fixed position on the barrel... meaning the fast burning powders typically used in 300 blk have reduced in pressure by the point the bullet passes over the gas port to not have enough umph to cycle the action...it may not be a function of the gas port size but rather it's location and distance in front of the chamber. This is why most 300 BLK barrels are pistol length systems. This is prob over gassed for most supers and about right for subs. Some guns are carbine length and get picky with loads they will cycle.

    All things being fixed in your rifle I would try for a powder that gives more gas volume or higher pressures for a longer period of time as the bullet travels down the barrel. 1680 maybe a good option for you to try

    Sent from my moto g(7) power using Tapatalk
    Last edited by John McCorkle; 08-19-2020 at 04:42 PM.

  3. #3
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    Texas by God's Avatar
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    Neat round in a neat gun. You'll get it running. Doesn't Ruger offer it in the Mini?

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  4. #4
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    W.R.Buchanan's Avatar
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    John: Call ASI . (303) 822-6849

    You probably need a Gas Bushing with a larger hole in it to make the gun cycle. Simple as that.

    Randy
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"
    www.buchananprecisionmachine.com

  5. #5
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    Just a long shot, John, but what about the magazine? Feed lips for the new cartridge and follower spring. Also, concerning the recoil spring, long one is too much and the short one not enough---maybe something in the middle? Could try the long one and keep chopping off a couple of coils until the balance is right. I wish you success with this project. I'm a Mini lover, have 3, but never altered them from original. Thoughts have been running through my mind lately about the new model being so much improved (according to the gun writers) that a new Mini-30 is starting to have some appeal.

  6. #6
    Boolit Master

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    Already tried a larger gas port. Tried cutting the spring down 1/2" at a time. Tried a little oil on the cartridge which seemed to help. Have a spring made with lighter wire which is a bit too light. Wondering if the mini 30 uses a different spring than the mini 14.

  7. #7
    Boolit Man
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    John Taylor...there is a forum website called perfect union. May try asking there as they have a dedicated forum to that platform of rifle and offer a wealth of knowledge. I bet someone has done the same thing and can help you. I learned a lot with my 7.62x39 Mini as in bushings to fix over gas and getting the mini to feed steel cased more reliable.

  8. #8
    Boolit Grand Master popper's Avatar
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    What ammo? That makes more difference. Subs, supers, factory or your loads. My AR15 carbine gas and pistol gas work fine for all factory stuff.
    Last edited by popper; 08-21-2020 at 11:49 AM.
    Whatever!

  9. #9
    Boolit Master

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    Factory new ammo is all I have to work with.

  10. #10
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    Gee...oiling the cartridge-- I don't know--maybe not a really good idea, although I see the idea behind it. But, if that helps, then perhaps you need to polish the chamber a bit. Same-o, same-o if the oil reduces the friction between the cartridge case and the chamber walls, polishing should accomplish the same thing. I know that in a firmly locked breech like a bolt action or lever action an oily cartridge case can greatly increase backward thrust and result in higher pressures and perhaps ruin headspace, but maybe not so much in a semi-auto where the bolt is meant to move backward. Still...I'd stay away from that approach.

  11. #11
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    W.R.Buchanan's Avatar
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    Call ASI they will tell you what is wrong with it. The Gas Bushing in a .300 BO is much larger than the regular Minis Bushing

    I gave you the phone #, it is a 5 minute call?

    Like above go to Perfect Union, but they are going to tell you to Call ASI.

    The new barrel on my Garand needed to have the chamber polished before it would cycle so maybe there is something there?

    Randy
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"
    www.buchananprecisionmachine.com

  12. #12
    Boolit Buddy
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    John,
    What type of factory ammo are you using to test fire? Super sonic BLK is loaded to around 50KSI, but subsonics may be loaded to below 45 auto pressure. Some factory subsonic loads just don't have enough umph to cycle a gas gun.
    Point being super versus subsonic ammo have vastly different resulting gas port pressures. If you happen to have subsonics, you may be conducting an exercise in futility.

  13. #13
    Boolit Bub Metrobluing's Avatar
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    I just happen to have a Mini 14 in 300aac , so I went and checked what bushing was in the gas block. I will say that the gas port in the barrel is .120 and the bushing is .065. I run mostly supers so i went with the .065 so I didn`t have to pick the brass up 6 lanes over. Now they only fly 3 lanes.

  14. #14
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    Quote Originally Posted by John Taylor View Post
    Factory new ammo is all I have to work with.
    you might even need a heavier spring. When I did my ar15 in 6.5 Grendel I fought it. It would shoot eject and not pick up another round. What I ended up finding is the bolt was traveling so fast that it wasn't giving the mag enough time to feed a round. It took a heavier buffer to cure but a mini doesn't have a buffer so a heavier spring is your only alternative. Its worth a try. You actually might have needed to go with a smaller gas port not a bigger or at least left it alone. I would think the gas system and spring out of a 762x39 would work just fine on a 300 bo using full power ammo.

  15. #15
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    Did you ever get this gun figured out?

    Randy
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"
    www.buchananprecisionmachine.com

  16. #16
    Boolit Master

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    Quote Originally Posted by W.R.Buchanan View Post
    Did you ever get this gun figured out?

    Randy
    to many other projects in the way. It's a freebee for my brother.

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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