Cylinder Throats on my .32-20

My brother has a set of pin gauges to today I measured the cylinder throats on my .32-20 S&W M-1905, 4th Change Military & Police. I hypothesized that if they were too large it would be the cause of the low velocities I'm seeing with it.

Nope, every one of them measured 0.313". Combined with the barrel/cylinder gap of 0.003" to 0.008" it's in spec. The only thing I can think of is the barrel. Some barrels are just slower than others.

To be fair, this gun is for informal plinking and target shooting for me, since centerfire rifles and handguns aren't legal for small game in PA, and I have much better choices for self defense, so the low velocities don't really matter.