I just removed an old non-mil spec collaspable stock from an ar15 and replaced it with a Vltor collaspable stock with all new buffer, buffer spring, castle nut, plate etc also from Vltor.  The switch over was easy, but after installation - when charging the weapon - the new spring inside the new buffer seems to make this awful scraping sound that I have never experienced before.  I placed the old buffer/buffer spring into the the weapon and did not get the scraping sound. Is this sound normal for a new buffer spring and will go away when the spring softens, or do I have some sort of problem?

Thanks for your help.

If your old spring lets the rifle function ok, mind as well use it...
Does the new spring or buffer have any burrs on them?
If the new buffer/old spring combo scrapes, you have your problem.
The scraping might go away, but the aluminum buffer tube will lose that battle.

Welcome to the site!

Thanks, the old buffer/spring combo has had several thousands of rounds through it with no problems.  Since I paid for the new buffer and buffer spring, I thought I would use the new parts.  Just wondering if it takes some extended range fun to make the "schhrrrooomp" scraping sound go away - or if I should just put in the old buffer spring.

Check the end of coil winds on the new spring,  If needed, use a file to remove the burs that are scrapping down the tube.  

Also, check the new buffer at the bumper roll pin. If needed, flush the roll pin even with the buffer with a file to prevent it from snagging the inside of the spring.