I saw where someone used a 3/32 roll pin for a bushing. What do you think?
If you are going to the trouble of taking down your gas block, have a real bushing in hand made from hardened steel to replace the existing one. There are many suppliers or pointers to supplier here on this site. If you buy only one size, get the 0.05" ID bushing.
While you are at it, order the kit with 0.045, 0.05 & 0.055" bushings so you can decide which one you want when you see what you have now. If you Mini has 40 foot ejection with 5.56 ammo like mine did, then you might like the 0.045" busing. If your Mini is ejecting only 25 or 30 feet, I would not go under 0.05".
You also need to consider what ammo you plan to shoot; if you go too small on the bushing, low powered ammo may make your Mini unreliable.
You may also want replacement screws that can be torqued evenly, as the stock ones are stacked in place and the thread damage can make things tricky. I went a step further and used a finishing tap to clean up the gas block treads and used an actual torque wrench in steps of 2 inch-lb...