Got pics of yours?
84minieldo wrote:Must be a newer one than mine,this has a flat top while mine is rounded
I just ran across what I think may be a M48 that is similar to yours.
This earlier (S/N 052xxx) black gun has a different slide and the buffer is built into the frame just like you see on a Model 38. The slide has far less material at the muzzle end, and as 84minieldo points out in his post, it's more rounded. Also the grip screws have brass collars around them -just like you find on the wood grips of early model Jennings J-22 pistols.
The later (S/N 568xxx) silver gun has more material at the muzzle end of the slide, is slightly more angular, has a flat top, and the buffer consists of a spring on a collar that is free to travel down the barrel under recoil - just like we see on the M58, M59 and Jennings Nine. If you look closely, you will see a recess cut in the slide to accommodate this type of buffer. (The later buffer will NOT fit on the earlier frame.)
Another difference: The serial numbers on these two pistols are positioned in similar locations- but they are on opposite sides of the frame.
Interestingly enough, the diagram on the factory manual shows the later model. So it would seem there was a design change at some point, perhaps due to slide failures? We will never know...