Hi, yeah I don't recommend sorting the inner barrel on the peacemaker due to design..
I have the airgun versions on the peacemakers but they use slightly different cartridges to yours.. Mine are rear loaded not front loaded..
Now for the Asg Dan wesson revolvers you can get low power cartridges/bullets for them but I have not seen them for the colt saa peacemakers but the older Dan wesson cartridges used to fit the peacemakers so you could try though, unfortunately though unless you know someone who has them or know a shop that sells them and will let you try them, you might have to take a punt on it.
ATB Marc