Ok, I've never reloaded before and am going to be doing my first batch very soon. I've got 1k 62gr bullets and the like to reload. I also just got my first can approved, and have no subsonic ammo. A buddy suggested reloading the 62gr to subsonic, but I believe you need a much heavier bullet. Am I correct? It will be for mainly a 10.5" AR and some will be shot from a 16"
I use 5.0 of trailboss under a 60 grain soft point in federal or black hills brass and any primer. I've used cci 400 & 450 and I believe it was rem 7 1/2 and they all worked. It doesn't cyle the action but is damn quiet. Your gonna get some guys that will say it's a waste of time because your slower than a 22lr but I do it for the fun of reloading. Just make sure they stabilize in your gun before your attach a can and it'll all be good.
Now there is some subsonic ammo out there that will cycle but it's pricey and there not saying what kind of powder it is.
Just so you know, there are other concerns than cycling the action.
Most silencer companies wont warranty their cans for subsonic 223. The reason is that the bullets dont like to stabilize at those speeds. Baffle strikes are much more likely. If you decide to do it, more power to you. Just check your loads very closely for any signs of keyholing or tumbling.
Most folks will tell you that youre just reproducing a .22 LR when you load subsonic .223. I dont exactly agree with that, as you have a very wide selection of bullets to choose from and with powders like trail boss and whatnot, you have alot of different options. On the bright side, you dont have to worry about wearing out your brass.