I'm about to put in a order for a firing pin stop for my Mil-Spec. It's a 45 but do you order one for the 38 or the 45, some one told the 38 since it has a 38 firing pin. But I'm thinking that Springer uses a priority type firing pin more or less.

Here's a short summary on FP stops.  The diameter of the FP, regardless of .38/9mm, .45, or whatever, is the same at the rear.  So, what's the difference between the various stops?  

First, there is the difference between a Series 70 and a Series 80 stop.  A Series 80 stop has a relief cut on the lower right side.

Second, the difference between .38/9mm//40/10mm etc. stops and .45 stops is that the smaller caliber stops have a relief cut on the lower left to compensate for the wider ejectors of the smaller caliber guns.  You can easily modify a regular .45 stop for .38/9mm, or you can modify the back of the ejector.

There are other things to consider too, like whether the stop is oversized, whether it's unfinished at the bottom, etc.  Stay away from stops that are uncut at the bottom, unless you're familiar with firing pin stop timing.  

I hope that explains it.  For the Springer in .45, you want a .45 stop, Series 70.

Thanks Hobbs, I was looking at the Caspian oversize stops. This Information helped.