I googled and found, I think, 3 dealers but no website to see inventory of their stock. One is in Pacifica where I'm staying. Years ago I bought stuff in the San Fracisco Gun Exchange, sadly long closed. On this side of the Atlantis we imagine that your gun stores have a huge stock but I know that's not true. They can't keep everything I know,but seeing I'm there I wanted to take advantage. Cabelas was a shock. No store in all of California.
The closest thing to a Cabela's in magnitude is the BassPro Shop chain store in Manteca, which is East of S.F. and about an 85 mile drive from Pacifica (where I used to live). For sheer variety and inventory, it is probably the best bet option for you if your time here is limited and you need to maximize results. Rather than wasting a day driving around to the smaller local shops hoping to find what you're looking for, make it a day going to BassPro.
California has such restrictive laws governing firearms sales that Cabela's doesn't want to play here, the best they could do is set up shop in Verdi, Nevada which is not far across the CA state line and West of Reno.
It is hit and miss and all depends on what you're specifically looking for, but in any case, you're going to need to get away from the locations immediate to S.F. in order to find something decent.
Many local shops concentrate mainly on the "tacticool" stuff... AR-15's, AK's, Glocks and the accessories geared towards them. Revolver stuff?? You'll get funny looks... no one uses THOSE anymore.
Almost everything that's around here pales in comparison to what was the S.F. Gun Exchange... now that was one heck of a gun candy store!!
Also... instead of doing a Google search, use YELP.COM, which has customer reviews. When I needed to find a shop some 45 miles North of me in Sacramento to do a transfer for a private firearm purchase, a Yelp search really helped me narrow down the field to select a good one, which was MTG Firearms (shameless plug).