Problem with Uberti 1873 Sporting rifle .45 Colt

[fortyshooter]

I'm a newbie here,and maybe I can find out an issue with my  recently purchased Uberti rifle.
Bought it used from my LGS. Story is a guy sold it to them ,in need of cash,and the rifle supposedly had never been fired.
It looked brand new,and I got it for what I thought was a good price.  
Took it to the range today and it would cycle and fire 3 or 4 rounds,then the bolt/lever would not fully lock up.
Bolt would touch back of case head,but would stop short of the extractor going over the case rim.
This might happen after3 or 5 rounds....random.  Ammo was either HPR or Underwood,both look like Star Line brass.

One thing I did notice is on top of the extractor looks like it had a build up of weld on the angled or curved end of it,and was machined down to roughly .015 or .020 above original surface and re-blued. Would this be a factory fix before gun was sold,or
some local repair? Kind of strange on a supposed never fired rifle!  

Any of you Uberti rifle owners have lock up problems with various brands of ammo?  
I plan on calling Stoger Firearms,from whom this gun was sold, about this issue or fix.

This appears to be a great rifle and shoots well when everything is working correctly.
Thanks for any help or thoughts on this!

[fortyshooter]

Talked to Stoeger Arms,who imported this rifle.. great folks, said to send it in and they would check it out,and honor warranty,even though it is a 2007 gun. They are only a 3 1/2 hour trip from me,but the regulations are you have the ship it to them.
Upon further trouble shooting,looks like if the case rim doesn't have enough bevel or chamfer around the primer end,the extractor has a tough time going over the rim edge to lock in the bolt.
I really don't want to chuck up hot rounds in my lathe,to lightly chamfer the case rim edge!

[Cactus Mac]

Keep us informed about what Stoeger does with it.  It sounds like a simple extractor replacement.