If they drop in the chambers of your cylinder all the way to the rim no problem. When you are at the range load 6, shoot one and measure the rest for pull. Shoot another, and measure again, and so on until you get to the last round. IF you have seen no increase in lenght, load 5 more and repeat leaving the last of the first rounds in place. Repeat the checks again, just to be sure. If the last round it makes it through two cylinders worth of rounds with no increase you should be good to go.
ALso depending on just which BH you have you might go a bit more conservative with your loads until you find out just how much you really like.
I have a Redhawk and find that much over the RCBS 270 SAA is overkill even loaded into Ruger only levels. My main load uses a 255 - 265gr RFN design or HP I pour myself. I also have a mold which is a version of the 270 SAA which has HP pins as well and they shoot excellent, but I have yet to put on into anything on 4 legs just yet. It's not been for a lack of trying though. With cast loaded in weights from 200 through 310, I have found nothing wanting in accuracy nor penetration from the middle weights nor much of a need to actually get aggressive with the powder. The mid ranged loads have all out preformed any of my initial expectations.
If you haven't shot any of those big boys, you might be in for a sore knuckle so be aware of that trigger guard, it can and will bite. You might find as I did that even the 255gr bullets will penetrate way more than you think they will even at muzzle velocities down around 850 - 1000fps. Coupled with the nearly half inch hole they start off with, makes them a very formidable load. Even with my 454 my heaviest cast loads are only using the 300gr RFN at a modest 1550fps. I have run them up into the 1700fps range from the 8.375" Raging Bull and to be honest, if I needed that much power in a handgun, I would much rather have a rifle instead.
If you haven't had the chance look up the following and do a bit of research. You might find that you will be way more impressed with this fine old round without going to the extremes.
Linebaugh's Custom Sixguns