How to determine caliber of rifle?

[radar]

I am new to this site (and to flintlocks).  Just purchased a rifle built by Art Holly and has Bill Large barrel.  Very pretty old rifle and does not appear to have been shot much.  I was told it was a .32 but I can insert a .358 diameter rod in the muzzle.  Measured muzzle with calipers and get around .405.  I'm leaning toward a .40, but it may be funneled as I have read on this site Mr Large did this sometimes.  Any help/ideas greatly appreciated.

[Bob Roller]

If you have a "funneled"Bill Large barrel,I can tell you now that Bill didn't
do the funneling. Find a machinist with a set of small hole gauges and have it
checked properly.Dial calipers are erroneously called "Verniers" but a lot
of us called them "Verynears".

Bob Roller

[Dennis Glazener]

I am new to this site (and to flintlocks).  Just purchased a rifle built by Art Holly and has Bill Large barrel.  Very pretty old rifle and does not appear to have been shot much.  I was told it was a .32 but I can insert a .358 diameter rod in the muzzle.  Measured muzzle with calipers and get around .405.  I'm leaning toward a .40, but it may be funneled as I have read on this site Mr Large did this sometimes.  Any help/ideas greatly appreciated.

I assume you want to verify that it is in fact a .32 bore? If so an easy way to do this is by gently inserting a 5/16th drill bit, using the smooth end not the cutting end of the bit. The 5/16th bit is .315" and should slip into the bore beyond any cone/funnel cut in the muzzle.
Dennis

[oldarcher]

I am sure that there are many more knowledgeable people on the Forum than I, but this is how I measure bore diameter.
Make sure that the barrel is clean, then lightly and thoroughly lube the barrel. Select a lead ball slightly larger than the barrel and gently tap the ball completely into the barrel making sure that it contacts the grooves completely around the barrel. Carefully insert a ball puller into the ball and remove it. This will give you an accurate slug that can be measured with a Mic or Vernier. I always do this with a new barrel, or one new to me, so I can determine a base to start my load workup. Hope that this helps. Good luck with your rifle!