Is there any difference between a H&R shikari frame(A prefix) and a H&R Topper frame(BB prefix), in the way of strength? I have read the Shikari frame is cast, but what about the topper. Both have a color case finish. The topper is from a 357 Max caliber. I have a NEF in 357 max(not rechambered 357 mag), that I thought about fitting the Shikari barrel to, but if the Topper is just as strong, then I will use it instead. Thanks