Since you specify Ruger, 44mag.
If you buy a 45 Colt, you will likely have to finish the gun but reaming the throats.
Not a big deal. Just a known detail Ruger has been getting wrong for 50 years.
Like both, prefer the 45.
4 5/8" makes my 45s nice to carry.
10 1/2" makes the SBH nice to shoot.
