According to wiki, the three types of copper pipe have the same exterior diameter, but due to their varying thicknesses, they have different inner diameters, which accounts for the different pressure drops for pipes of the same exterior size. [ref: wiki]... Three different kinds of copper K, L, M with pressure drops of the order of 45% higher in K compared to M. Looks like the type of copper will have to be discovered too.
I'm certainly learning a lot more about piping than I had intended.
ps. For future reference, Jonathan212's assertion is correct, and is based on the chart and equation on page 79 of the Copper Tube Handbook pdf mentioned earlier in post #69.
Table 14.6 is based on the Hazen-Williams formula
P = 4.52*(Q^1.85)/(C^1.85 * d^4.87)
P = friction loss, psi per linear foot
Q = flow, g.p.m.
d = average I.D., in inches
C = constant, 150
and per wiki: