Rank Insignia Pins on Flashes

[Jawn]

As to the rest, I'm a Chief Petty Officer with 20 years in the USCG and and while I'm proud of my service, my branch, and my anchors, I wouldn't wear official uniform items such as rank insignia while in civilian clothes. There are plenty of service related items I'll wear out of uniform, but anything that actually goes on my uniform has no place on my civilian stuff.

Just my $0.02. As has been stated, you do as you please, but you might check the USMC uniform regs, they might have something to say about mixing uniform items with civilian attire.