My group went on a Suborbital flight from Sea-Tac to LAX. One had a legal SIN, and legal guns attached to his SIN.
Aside from flying without luggage, they wouldn't have blinked twice at that, aside from demanding that he put his guns in a lockbox (Which they did.). The lack of luggage part got him "Randomly" selected for questioning, and a full-body cavity search from Bertha the Troll.
As for Military-Grade Gear, I can see Pistols, Machine Pistols, SMGs, and mass-produced, old Assault Rifles (Such as AK-97s) being common to gangs. They are today, in "Peaceful" Canada no less, and we're nowhere near as bad as Shadowrun is. (I got to see a bunch that were turned over to the local armoury in Northern Ontario. I'd hate to see what the cops collect in as violent a place as Winnipeg where I currently live!).
We're talking older, mass-produced items here. Uzi-IIIs and Ceska Black Skorpions for Drive-Bys, and AK-97s for base defence! Lower-end gangers are happy to have a pistol of some sort, even if it's just a Streetline Special churned out by a Microlathe somewhere in the Barrens! And none of these would be in good condition either. It takes training and disipline to maintain weapons properly, even something as simple as an AK.
Gangers with Ares Alphas are right out. Or any of the other new toys out there. Colt Goverment 2066s? HA! Colt Goverment 1911A1s is more like it!
MAYBE Philipean Knockoffs of Chinese Knockoffs of Russian RPG-7s in
VERY limited numbers in
BIG gangs, for those special occasions. ("Alright Spikes! Today we're knocking over a tractor-trailer full of BTLs and other drugs Lone Star is sending off to be destroyed!").
Sniper Rifles with gangers, hell no. But, get a semi-decent SIN, and you could easily get a Sporting Rifle of some type for "Hunting" at
Wang's Huge Gun. With the Bi-Pod and Scope!
Of course, that could cut into the gang's food, and, more importantly, beer and chips money!