baltimoreed
Well-Known Member
Having built a Mini 30 into a M1a I decided to do another one so in 2018 I started on a T20 Garand build. The T20 was an experimental .30-06 select fire, 20 rd box magazine fed Garand. A predecessor to the M14. They couldn’t get it to run right until the ‘06 round and bolt were shortened enough to give the bolt more time rearward allowing enough time for the mag spring to work correctly. It also would run hot too. Anyway I had Accuracy Systems install a 300blkout bbl with garand bbl external dimensions on my Mini14. I had a friend /local smith do the garand gas cylinder splines and threads. He also combined the rear of the Ruger op rod and the front of the Garand op rod. We did a wag on the gas hole size and op rod spring. When he gave it back to me it would barely move the bolt with factory blkout ammo. I lightened the op rod spring and enlarged the gas port and messed with a bunch of powders. I finally got it to reliably cycle using a case full of LilGun. Of course there were setbacks. The stock is a standard garand stock but the mini action is 3 inches shorter than a garand. There’s a lot of wood and jbweld in it. Initially it was running ok but when I installed the ruger steel reenforcement I changed something and it wouldn’t run. After a lot of tinkering it’s running again. The issue is the garand’s gas system is at the end of it’s bbl so there’s no bullet dwell time so in a bbl that long and a case so small there’s insufficient pressure being created to cycle the bolt and strip rounds out of my mag. It would do 7 rds but that was about all. Solutions were shortening the bbl, op rod, stock and starting all over or I could find a bigger [.223 sized] case that could hold more powder. I came across the 300Hamr in my searches which I’m hoping will work. 
