I have wanted a Delta Elite since they first came out.  Now that they are being produced again I am going to buy one.  I have a pretty much unlimited supply of .40 so I was wondering if it is possible to have an extra .40 barrel fit to one?  I know I would likely  need a different recoil spring and mags, but are there any other issues?

I did this with my Delta Elite, though mine dates back to the Reagan era.  Shouldn't be a problem.  Yes, a milder spring might be required, and actual .40 S&W mags if you are going to use .40s loaded to normal .40 length.  Some people just seat the bullet out a bit and use the 10mm magazines.  I do this with the 357 SIG barrel I also fitted to my DE.

The only fly in the ointment is this.  The ejector is shorter for the 10mm than it is for the .40 S&W.  Not a big deal for play, and it never caused any problems with my Delta Elite.  Still, there is a bit of difference, and I only use the .40 S&W barrel and the 357 SIG barrel for range use.  Same thing with the 9mm barrel.

The rim of the 9x19mm is very close to the 10mm/.40S&W breechface.  So close that a 9mm barrel actually functions in my Delta Elite with a lighter recoil spring and proper 9mm mags.

Yes, even a .38 Super barrel will work.  Very versatile package, the Delta Elite.

I have been interested in doing this with my Kimber 10mm and have been wondering the same questions but have been too conservative to spend the cash

Thanks for the info!