C:B ratio

[Cpt Obvious]

I read on the wiki of the BurntLatke study of C:B ratios. Using the second graph I calculated this.

With a 7" chamber of 2" sch40 PVC the inner volume would be roughly 27.489ci

A 36" barrel of 1.5" PVC would give me a volume of 73.289ci which makes a C:B ratio of 0.375, and according to the graph i should expect something around 400 FPS (which is my goal).

My question is did I read the graph correctly and Is this a reasonable expectation? I assume the study used metered propane and a standard potato, but did I miss something?

[jackssmirkingrevenge]

http://www.thehalls-in-bfe.com/HGDT/

[Cpt Obvious]

ah, thank you once again, just what i was looking for.