Raedwald, I shot on the USIMLT 'Short Range' team from 1999 thru 2009, & specialized mainly in the prone events (Maximilian, Whitworth, & Minie).
As you have already stated the Crocket is a roundball rifle, with the slow twist rifling that it requires. Unless there have been additional matches added to MLAIC competition all the prone matches are shot at 100m, & the only one that the Crocket would qualify for is the Whitworth (Percussion Free Rifle - Roundball or Bullet). To be competitive in this match a conical bullet is a real advantage. For the Whitworth my first rifle was a .451" caliber repro of a Rigby target rifle & then later a copy of the American 'Fisher' rifle in .32 caliber with a 1:14" twist barrel & a 208gn reverse tapered bullet, both rifles were quite capable of MOA accuracy. Unless conditions were very windy I felt no disadvantage in using a .32 caliber, but I feel a .40 or .45 would be a better all round choice.
The Maximilian event is only for Flintlock Free Rifles & only for roundball. In this match the overwhelming caliber of choice was/is .54 which is what I used in my custom-built English style sporting rifle with aperture rear & hooded post front sights. Even with the comparitively heavy .54 ball I can remember shooting in a heavy cross wind at the 2008 World Championships in Australia & even with my rear sight's windage adjusted all the way across I still had to hold on the edge of the paper of the target belonging to the competitor next to me.....that was some serious wind drift! I was the top scoring US shooter in that event that day (but not the match winner), & managed to salvage a bronze medal for the USA in the 'Lucca' 3-man team portion of the competition. I feel that if I'd be using a lesser sized ball/caliber I wouldn't have done so well that day.
The only other prone match is the Minie which is only for Percussion Military Rifle with appropriate projectile style (ie. Minie, Wilkinson, etc., etc.), so the Crocket wouldn't apply here either. In fact the only match to which the Crocket could be competitive, with appropriate changes to sights, is (in my opinion) the Vetterli which is for rifles of any ignition system (Percussion, Flint, or Matchlock), & any style of projectile. However, generally speaking, with the current level of competition any score below a possible 100/100 wouldn't get you a place, so you really need to take every advantage you can.
My recommendation would be to go with a small to medium (.32 - .40) caliber fast twist rifle for a conical bullet with good aperture sights, something akin to the style of a Gibbs or Rigby, etc. & use that with a sling for Whitworth & without for Vetterli.
One of the reasons I gave up shooting with the team on the MLAIC circuit is the number of guns required to compete (most events require a certain type of gun, usualy not useable in any other), with the associated paraphenalia for each, all of which created a lot of expense & logistics when traveling cross country &, especially, overseas. For the European Zone shooters it isn't quite as bad as their area is more compact as far as travel is concerned, with the exception of the occasional overseas event whereas the Pacific Zone (USA, Canada, Japan, Australia, South Africa, & New Zealand) competitors have much more air travel involved.
Best of luck with your decisions.
