There's an article devoted to the .30 Gibbs in Wolfe Publishing's "Gibbs Cartridges". It may still be available. A good bit of load data with bullets of all weights, but, as I recall, the data looked pretty warm.
Pretty warm? How so? Why would you drive a Ferrari around in 2nd gear? Barrel length is 26" in the article, but the author doesn't specify what amount of expansion he considered to be standard vs. max. My 26" 30-06 Ackley has beat those speeds by a little bit with admittedly warm loads. Still able to use the same brass more than 4 or 5 times & primer pockets are still snug, the brass is finally giving up to longitudinal neck splits after 30 years. The Gibbs has a bigger boiler than the Ackley so should be able to get faster speeds with all else the same.
Interesting book. Frontal ignition sounded like a good project to check out when I was younger & still had the resources to try it. I dunno about older & wiser, but older & lazier for sure.
