I have an old army 45 and an extra slide which I'd like to change to 40Cal.
What do I need to do to accomplish this and still convert back to 45...
Anybody know for sure.
If the slide is originally made for .45 Auto, the breechface will be too wide for .40 S&W, the extractor will not line up, and as previously mentioned the ejector length is different.
Get a slide for a Delta Elite in 10mm. The 40 s&w is basically a shortened 10mm. Same case size, just a diffent length. The breachface will be the same. Get some Delta Elite magazines too (I have one I haven't gotten rid of yet) and a barrel for 40 s&w. Once you have all the above, you can switch back and forth at will.