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Discussion Starter · #1 ·
I recently got a mini 580 series with 1 in 9 twist. Consistently hit 3-4" groups off a bag with Simmons 3-9 scope. After reading thhese forums, decided to try the easy first. Bullets, - best results were 69 gr hpbt, added muzzle break welded to front sight, and made a new gas port bushing with a .042" hole. Now dropping brass about 10', and consistently holding 1.5" to 1.25" groups at 100yd.
 

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Welcome to the board! Great to here you have a good shooter. Did you try regapping the gas block screws?
 

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I recently got a mini 580 series with 1 in 9 twist. Consistently hit 3-4" groups off a bag with Simmons 3-9 scope. After reading thhese forums, decided to try the easy first. Bullets, - best results were 69 gr hpbt, added muzzle break welded to front sight, and made a new gas port bushing with a .042" hole. Now dropping brass about 10', and consistently holding 1.5" to 1.25" groups at 100yd.
Would like to know more on how you made the port bushings. Size specs if you can.
 

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Great shooting gun you have there!
 

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Discussion Starter · #8 ·
Mini 14 Accurizing

Would like to know more on how you made the port bushings. Size specs if you can.
Hi, Bushings were stainless steel, .185" dia, .300" long, with a .042" dia hole. I don't think dimensions are super critical, because the gas block housing pinches down on both ends. Tighten the housing all around gradually, & use blue locktite. Might need 4 new 4 mm screws. I use 23.5 gr. IMR 4895.
 

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Hi, Bushings were stainless steel, .185" dia, .300" long, with a .042" dia hole. I don't think dimensions are super critical, because the gas block housing pinches down on both ends. Tighten the housing all around gradually, & use blue locktite. Might need 4 new 4 mm screws. I use 23.5 gr. IMR 4895.
Thanks
 

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Aren't the factory bushings aluminum so they'll "crush fit"? Wouldn't a steel bushing, unless sized just a tad over flush, induce some distortion in the gas block when torqued down? Anyone tried brass or copper bushings? Have I asked enough questions? :)
 

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Looks like a good weld job on the flash hider.

A word of caution on making your own gas port bushings out of something less hard than stainless steel. The bushing is what keeps your gas block from sliding down your barrel. With a softer metal the gas block will peen or bend the bushing. I know because it happend to me. It's a bear to try to drill out a bent bushing that grabs the bit and just spins! :angry:
 

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A word of caution on making your own gas port bushings out of something less hard than stainless steel. The bushing is what keeps your gas block from sliding down your barrel. With a softer metal the gas block will peen or bend the bushing. I know because it happend to me. It's a bear to try to drill out a bent bushing that grabs the bit and just spins! :angry:
this is true, the gas bushing on my S/S M30 is some grade of tough S/S. I made my own 'blank' bushing ground to the correct length out of a piece of injection mold knock-out pin this turned my M30 into a straight-pull bolt action.
I now have tapped the gas pipe for an 8/32 set screw (use plenty of lube and a sharp tap to do this if you attempt it the pipe on my M30 is some tough stuff) which is easy to R&R.
 

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Discussion Starter · #14 ·
Sorry I missed your question. I got the flash hider from Midway, but unfortunately it was for the older series (140?), mine is a #580, so I had to bore it out & weld it to the sight block. Works fine. I'm still using the .042" bore gas block, & still getting 1 1/4" groups off a bag with a 3-9 scope & 69gr handloads.
 
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