Hi,
I have a lot of data but I measure those things from the breech not the muzzle because muzzles on originals may have been shortened slightly during use. Moreover, I measure to the pin hole, which is almost always centered on the pipe and the 2 small tabs on the forward pipe. Because pipes varied in length a little, the pin locations are more precise. These measurements are averages based on 4 pattern 1756s, one used at Bunker Hill and another in Burgoyne's campaign.
Distance from breech to pin for rear pipe 14 1/8"
Distance from breech to pin for third pipe 22 15/16"
Distance from breech to pin for second pipe 30 13/16"
Distance from breech to rear pin for forward pipe 36 15/16"
Distance from breech to front pin for forward pipe 38 15/16"
The front of the forward pipe is 2" back from the front of the nose cap.
Barrel should stick out from front of nose cap 4 1/4" to 4 3/8"
These vary a little because of variance in the lengths of pipes.
Distance from rear of first pipe to front of second pipe 4 1/2"
Distance from rear of second pipe to front of third pipe 6 7/16"
Distance from rear of third pipe to front of rear pipe 7 1/4"
As you can see the pipes are not spaced evenly. Make sure the lug on the barrel for the forward sling swivel is just ahead of the second pipe so the swivel rests against the pipe when the gun is help muzzle up. That way the ramrod groove is not blocked by the sling.
dave
