Alll the reasons given have some validity.
Its definitely hard to find barrel making machines with beds long enough to turn out 60 inch barrels. Most come with a 48" bed, and when you deduct the length of the tail stock carriage, a 42" barrel is as long as they can make.
Stocks for longer length barrels cost a premium, if you can find them at all. Again, part of the problem comes from the available equipment for turning these long stocks out in a " pre-carve format for hobby builders.
Gun cases for these long barreled guns are also more expensive, and harder to find.
Shipping costs are going to be higher on the longer barreled guns, as mentioned.
Its even more difficult to transport these guns in a truck or car when the barrels get so long, as they simply won't fit across the width of most cars, or trucks. Even in vans, the room needed to transport these long barrels uses up space that otherwise could be used to transport other items.
Years ago, 2 friends of mine went deer hunting in Southern Illinois, driving down in one man's Jeep. The guns used did not have barrels longer than 42" but the guns were both flintlocks, and had to be placed on the floor of the jeep running lengthwise between the two bucket seats, on out to the back tail gate. All the rest of their gear was piled on top of the guns, after sleeping bags, and pads were used to pad and protect the guns from the weight of tents, cooking gear, poles, etc. On the way home, they stopped at a rest stop where the IL. Dept. of Conservation Police were doing checks of all cars of hunters. The officers wanted to check the guns of all the hunters. My friends had to unload the entire Jeep to get to the guns, of course, and when the officer saw that the guns were flintlocks, he didn't want to have anything more to do with them. It took the guys more than an hour to repack that jeep and continue on their way home.
Both men commented on the fact that if the guns they took were shorter, they could have packed them on the top of their gear, where they would have been easily available to show the officers.
Oh, check the height of your gun safe to see just how long a barrel you can fit into the safe. Most will not take even a 42" barrel.
My point is that everything about owning a longer barreled gun involves greater expense. Most people still think we are crazy to hunt with a gun that has a barrel longer than 30 inches as it is. There is no question that owning and using a barrel that is 46-60 inches long is going to involve a lot more expense. That is why you see no commercial manufactured with these lengths of barrels. There simply is not much of a market for these guns, yet. Thankfully, we have custom builders like our own Mike Brooks, who make these long-barreled fowlers, and keep the idea a present reality that is no longer confined to museum collections, and pictures in books.
Grinslade's book is no doubt responsible for a lot of Flintlock shooters showing an interest in owning and shooting a long barreled Fowler, just as you are showing interest, now. Good luck! :thumbsup: