Heavy/Support Weapon bag recommendations

Looking around for any players who use larger replicas, as I am interested in how you store/transport them. I am having a difficult time finding a suitable bag for my GPMG, since finding cases/bags for relatively flat non-bolt action and/or scoped rifles longer than 40" seems to be hard enough as is - I have a Plano 1502-01 for my 48" long AR-10 and the bipod picatinny mount is too wide for the case to handle, I have to bend the shell to snap it closed. Here's what I need...

- Able to hold a weapon 48" long and roughly 6" wide max with the ammo box removed. Compartment for ammo box not necessary
- Does not have to be a hard case, nylon bag with no rigidity is fine
- Does not need to have backpack straps or rolling wheels
- Able to handle moving a 25+lb replica and ammo, I have not had good experience with pluckable foam in this regard
- Does not need to be form-fitting or padded, I don't mind wrapping it up in a towel or something prior to transportation

What I have seen so far is along the lines of sniper rifle bags, camping duffel bags (long enough but far too girthy), and interestingly enough travel cases for golf club bags.