If sabots and jacketed bullets are illegal, then you need to go to a conical. You want to get one that is not hollow point because you need penetration out of it. Hornady Great Plains Conical, T/C Maxi Ball are a few to try. There are some others out there like the Colorado Conical (I think they are called). All of them well penetrate deep and cause good internal damage.

Another thing you might look into is a 348 grain Power Belt in an Aero Tip. These with 100 grains of powder give excellent accuracy out of most inlines and even sidelocks. With the Aero Tip you will get excellent penetration and they should expand real good also.

Keep your distances under 100 yards and you should be fine. Depending on the rifle you have, you need to get some and start shooting. Start at 50 yards and see what kind of groups you get. Then move back and see if they hold up well.

I have some custom conicals and R.E.A.L. conicals that I shoot out of the inlines that do a real good job. The biggest of them being a 533 grain conical and out of my Black Diamond they would be fine to 100 yards.

There is the option of round ball. In this case you need to watch your distance and shot placement is a key element. Also I would head to as large a caliber as I could get my hands on in the rifle department. I have a .58 caliber that I was shooting today and would be confident out to 100 yards with it the way it shoots. Also they have a lot more weight per roundball then the .50 caliber. Roundball will penetrate well, but if they hit anything once they enter, there is no telling where that ball will end up.