Ok, that all makes sense too .....since we shoot skeet in 12ga, 20ga, 28ga and .410 ....( I was asking because it was not impossible to have a 16ga in there ...just never know ).
What you have is a nice set of guns ...with fixed Skeet chokes...and I don't know probably made sometime from the 1950's - 1970's .../ and the pictures make it look like a standard grade receiver with an upgraded stock / with some nice grain and color in it.
You might consider calling Browning and talk to a live person, see if they can give you a little more info on when that set was made / was it made as a complete 4 barrel set ...or did someone customize it down the road. Ask them if the set was sold with one forend ...or should it have had 4 for-ends as part of the set.../ they should know.
Value ...for insurance purposes, I'd probably say put $ 10,000 on the set to be safe for replacement value. But as an example, in the Citori lineup - Browning brought out a 4 barrel set last yr ...and sold them new for around $ 5,000...but I don't remember if they were 26", 28" or what they were...
These days 26" Skeet guns are not in "vogue" right now .../ with the trend in the last 10 yrs going to 28" or 30" barrels - and even some at 32". Personally, I shoot 30" in all 4 gagues - so this set might be a little difficult to sell to a serious "Skeet" shooter - but its a set of guns that has some nostalgia to it - back to the times where it was common to shoot shorter guns / and some guys still do.
I hope you're not trying to sell them / and I hope you shoot them and enjoy them ! However, if you have to sell them / or if the guns don't fit you --- or don't want to shoot Skeet with them ...I think today's retail value for the 4 barrel set is probably around $ 5,000. Your primary market - if you're going to sell them ...is to some of us older "skeet shooters" ( guys over 60 for the most part ) that want to make them part of our collection ....vs a serious competitive skeet shooter these days...
You should take them to a knowledgeable shop in your area, if you have one, that deals in higher end "Target grade" or "Skeet guns" ....not a big box store ...but maybe a used gun dealer ...like a Cabelas ...or somewhere where you can let someone really look them over closely - and document what Browning can tell you ....to really tighten up the value / have them appraised.