weight differences

[bob hertrich]

Is there any appreciable weight differences between a 20 ga and a 28ga octagon to round barrel. I am going to try to build a very light British fowler. I have a .54 cal long rifle that could use the same ball if I use a 28ga.

[rich pierce]

If they are in the same profile then yes, there will be a difference. Many to most fowler kits had heavy barrels better suited to buck and ball till recently.

[bob in the woods]

If you order the barrel from a maker, you can have the barrel profile reduced to accommodate the smaller bore.  I had a 28 bore 25 years ago which was a done that way.  If a kit, then usually the kit is designed with a 20 bore barrel, and that profile is retained even when the bore is reduced.  As for using the same ball in your smoothbore as your rifle; maybe not .  At the time I used a .535 ball in my .54 rifle which was too large for the smoothbore.  There's no rifling so the patched .535 wouldn't work.  I had to go to a .527 ball for the 28

[Daryl]

The rifle's ball would likely only work if you didn't use a patch in the smoothbore, just overshot wads or something else to hold it on the powder.
In my testing, non-patched balls did not shoot as well as patched balls, thus I would suggest as bob noted, a .526" or .527" ball. That might even
be a bit snug for a decent patch.