SOT - shortening mini-14 barrel advice...

[mordecai]

Please... forgive for what I'm about to ask, but you guys are
just too knowledgable to go elsewhere.

I'd like to shorten the barrel on my Mini-14 and permanently
attach a flash/brake for an OAL of say 16.5" to keep it all legal.

Anybody have any insight into the removal and installation of
a Mini-14 barrel?

Any ideas on what I may need to do to the gas adjustment
to keep it cycling with a shorter barrel?

Isn't there an adjustable gas system on the market somewhere?

Thanks.