One of the most common Grizzly questions I hear is: "what calibers did they make conversion kits for?"
I will take my best shot to answer that here... As far as I know, they made the conversion units for the Mark I in .357 magnum, .45 ACP, 10mm, and .357-.45GWM. I always thought that the .357 mag was the most popular conversion but many tell me that the most popular was the .45ACP. I have been told that they also made a few units in 9mm WM, and my friend Jim in Corpus Christi Texas, who I consider to be "the" authority on Grizzly handguns, swears that he saw one once in .40 S&W.
I have heard people say that they never actually made a conversion for the .45 Win Mag because that was the standard caliber. But you could order the gun directly from LAR in any caliber you wanted. My best friend ordered his in 1989 in the .357 mag caliber and later they were more than willing to sell him a conversion in .45WM. As for the Mark Vs, someone else is going to have to help me out. I have seen conversions for them in .45WM, .44 Mag, and their original standard caliber of .50AE. I am not sure what conversions were offered for the Mark IVs... can anyone shed any light on the subject?