They have the long REAL bullets and the short REAL bullets. The short should work. If you get adequate accuracy with the long ones, so much the better. I would use max powder though, and hope that the lead doesn't strip.
C F
My own experience has been in that using the REAL, the "short" ones, or the ones with lighter weights, will work fine if the powder charge is
reduced just a bit.
In other words, if you are shooting a round ball, using 90gr FFg, then a good starting place with the REAL would be around the 70/80 gr mark.
I seldom get desireable accuracy out the heavy for caliber REAL, unless I have a 1:48 or faster twist...and faster is better in this case, because you can increase the powder charge in the faster twists. As long as you cast from soft lead, or buy REAL's cast from soft lead...to promote good "bump-up", or obturation, your chances of leading, or "stripping" in the barrel are much less. Hard cast REAL's will nearly always strip, no matter what lube you choose. But then that too is not the end of the world if you're getting good accuracy.
Of course there is always an expection. I have read of these exceptions, but I have never actually seen them work.
Once you get something working with the REAL, I think you will like them.
Russ