I decided to post these drawings from the old Texas Bull Shooter since they provide good basic information on a number of US experimental cannon rounds dating from the 1950s to the 1970s. Most if not all of the drawings were probably done by Robert Mellichamp and much of the information was provided by Bob Leiendecker (Past head of the Large Bore And Artillery section of the ICCA Bulletin) and Ralph Meyer.
Image quality- Keep in mind these are photos taken straight from the bulletin pages which in turn were produced via 1970’s vintage photocopiers.
30/20mm USN Exp., 30mm Grenade Cartridge, 20mm Caseless
30 x 120mmRB & 30 x 137mmRB SURE Gun U.S. Experimental
27mm-30mm Exp. Cartridges
26 x 130mm Colt
30 mm Cartridges Manufactured By AMRON
Some information on 30mm Aircraft Cannon Rounds, 1974
30 x 173mm GAU-8