asfar as factory ammo I found my mini-14 to like the white box winchester bulk ammo in 55 grain fmj the best. second best would be wolf 62 grain hollow points.

I also reload for it I achieved my best groups using federal match brass, cci small rifle primers, 25 grains H4895 powder, and Hornady 55 grain SXSP's. I noticed the mini-14 to favor lighter charge weights that push a 55 grainer around 3,000 fps pushing it any faster I began to see the accuracy start to go down hill quick.

I might try that barrel deresonator, im also lookin into having a better trigger put in too I like a 2 stage trigger so i will look for a softer one, the factory 2 stage is just a little hard for my liking. I have a muzzle break for it its the choate m-14 style one. heres a pic. if you go back to page 1 of this thread you can see a picture of my complete setup plus a 150 yard target.