Welcome, BUTCHER, and I hope you like it here! I'm not aware of any restrictions on propellant type but I'm no Schuetzenmeister. Seems to me that your projectile will certainly meet the plain-base-lead rule, and only a churl would try to stop you from shooting with them as long as you were safe (and didn't take any prizes;, of course, VBG). Of course, some folks seem to be infested with a 'Contrary' virus......

Many Schuetzen shooters also shoot air rifles for practice since they are so hold-sensitive, so you already have something in common  with some of us here. IMO an air rifle is the best training for offhand shooting and also a lotta fun.

I'd be interested to see just what kinda equipment it would take for an air rifle to be competitive @ 200 yds. I've used only the smaller calibers from 177 to 22 and they pretty much run outa steam past 50 yds, but I understand that a few folks are building larger-bore air rifles that are capable of much better ballistics at somewhat longer ranges. Can you enlighten us further?
Welcome again, Joe

     I'd be happy to.

     I will be testing the performance of my .45 caliber airgun this weekend with several loads at 50 and 100 yards.  It is expected to put out 144 grain roundball at around 900 fps.  I also will be shooting a .25 that will be putting out 42 grainers at around 950fps and that is the heaviest load available for now until I cast/swage my own.

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                                                             BUTCHER

     You are close.  The rifle in the picture is a Korean Sam Yang 909 44 Super Gun (it's really a 45).  The older (and better) two tube version.  You can get about 180-200fpe out of it stock.  Mine has been tuned-up to around 270 maybe 300fpe.  I'll find out this weekend when I shoot various loads through my chrony.
     My other air rifle is an AirForce Condor.  I am receiving the .25 conversion kit this week.  Going to see around 80-90 fpe out of that one until I can cast my own heavier projectiles.

                                                       BUTCHER

     I could really get into that sport.  I am going to see if the Lewis and Clark Air Rifle was available chambered in .25 so I can have a rifle custom made to compete with those quarter-bore guys.  Otherwise it's the .31-.32  I will have  three years to work on my aim for that is how long the waiting period is on that particular rifle.   

                                                                      BUTCHER