NVSmith, I generally refrain from using firearms and reloading analogies on a fuel economy forum. The old M91 had a 30 inch barrel, might even have been close to the 20MM but probably shorter. The bullets were cast lead, we have enough accumulated for about 150k 150 grain 30 cal rounds. It did take magnum primers to light the powder and the muzzle velocity was so low the sights needed to be set for 400 meters at 50 yards.
Plenty of unburned powder residue in the barrel. Bottom line was we are just cheapskates
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For super light loads use something like bulls eye or unique. Even the recoil was more of a push than the normal sharper hit of a conventional load.
Kind of like the standard Soviet surplus in a carbine, a semi flame thrower, not to be used in dry brush.
I think the Indy engines run about 16 to 1 compression. Even at 50% of atmosphere manifold vacuum, that's still 8 to 1 which is about the max compression of the early pollution control choked engines of the mid 1970s.
Even the cars sold as E85 capable do not (as yet) have the compression needed to run most efficiently on alcohol, but I thin in the next few years you will see the throttle control pass from a butterfly to more control by cam timing, possibly both lift and duration, individually or separately, on both cams.
regards
Mech