I Ran 126 rounds of CCI Blazer & CCI Lawman ammo through my Springfield Milspec today.

When I field stripped it for cleaning I saw something I never noticed before. There is a ridge around the Brl about 1/2" from the end of the Brl. If you run your fingers along the Brl you can feel it.  So I guess at some point I had a squib load with a bullet lodged in the bore? I don't know when it happened, the gun never malfunctioned today, I would be surprised if a squib had enough power to cycle the slide with a 19.5 pound recoil spring.

Is it possible this bump is a wear mark from the fit of the Brl bushing to the outside of the Brl?  There is no visible "ring" inside the Brl as with an obstructed shotgun brl.

What's everyone think? I can Emailo a pic if anyone wants to take a look.

It almost sounds like you are describing the slightly enlarged portion of the barrel intended to increase tightness of the bushing and improve accuracy.

If there is no "ring" on the inside and the gun functions, I'd just keep on shooting.

 That is normal for SA barrels and actually is meant to limit  barrel wear on the bushing and extend the accuracy life. A full dia barrel will eventually egg out the bushing and allow the barrel muzzle to move up/down in the bushing.
 Most high end 1911 competition gunsmiths will do the same thing to match barrels ..

I concur with the above.  I observe the same thing with my SA Milspec.

I agree with the crowd, it's probably fine as the end of the barrel is of larger diameter.
That "bump" should be all the way around the muzzle, with the worn spot being where the contact points are in the bushing.
Good catch, better to be safe.

Thanks for the info everyone.