oversized gas port with adjustable gas block

[tp555]

Use calipers to measure the gas port hole.They are cheap $10 or so.Gas port holes vary from .045" to .156" in the ar.At least I 've made them that size.Normal .223 stock 20" bbl.is .062".The 30/221 is usually .085" to .125"
depends on bbl length.Bigger hole throws the brass out father away in high pressure.Too big you will have problems and maybe nasty suprize.In the 30/221 with a pistol gas tube make the port big enough to cycle sub loads about .090"
for 16" bbl.Drops brass at your feet.Using high power throws brass 10 feet out.
Too big a hole shaves copper from the jackets and clogs up the port.

[RWBlue]

Originally Posted by tp555

The 30/221 is usually .085" to .125"
depends on bbl length.

In the 30/221 with a pistol gas tube make the port big enough to cycle sub loads about .090" for 16" bbl.Drops brass at your feet.Using high power throws brass 10 feet out.

Too big a hole shaves copper from the jackets and clogs up the port.

Now that is useful information (especially last line) and may keep me from drilling.