This is excellent. If I were trying to do this plus an extra barrel, do you think the sticks could be arranged to fit on the bottom of the foam (between the foam and the bottom of the case)? Or is the foam too thin for that?
I know others have stacked layers of foam, but they were in cases (resembling normal luggage like a Pelican 1560) that were much thicker. However, because the barrels and sticks don't require a deep pockets, I don't see why not. Best thing to do is call GunFoam directly and speak with their engineers. I've found them to be extremely helpful on a number of occasions. Before doing so, I would make sure you have all of the items (rifles, scopes, barrels, sticks...etc) you want in the case loaded into your account so they can reference it. You should also know what case you would like to use beforehand. In other words, be prepared.
GunFoam doesn't offer luggage style cases on their website that would afford the ability to have double layers of foam. Examples would be the Pelican Protector 1670 or Pelican Air 1615. You can contact them and see if they are willing to do something like this. Both of these cases are less than 62" linear.
Airlines can be tricky. As a rule, checked luggage has a 62" linear limit. Meaning length + width + depth must be < 62". However this rule is not
supposed to apply to "sporting equipment" like golf clubs and firearms. This is why the Pelican 1750 double rifle case, downhill skis/snowboards rarely catch the eye of a ticket agent. But something that "looks" like luggage but contains a firearm could draw unwanted attention and a possible freight charge...even though it's sports equipment. Ticket agents can be a PITA.
I know that
@Ed Lally has double layer foam for a Pelican Air 1615 for firearms. I'm not a big fan of the Pelican Air, but it is a lightweight solution that affords a little more space than the Protector. Albeit at the expense of a slightly less durable case. I'd be interested to know what GF says if you talk to them.