Vulcan 3 barrel depth

I just inserted a magazine and pushed the barrel up to the mag. Then I popped the mag in and out a couple times to ensure operation was good and that things weren't loose but still had some room to slide in and out without being too snug. Hope that helped. @zx10wall, @Motorhead, @K9Air know just about everything about these guns so maybe they can chime in and confirm.
 
Bought a used Vulcan 3. I can't insert the magazine as I believe the barrel got pushed back during shipping. Is there a spec or just make it clear the magazine?

Thanks, Scott
The V3 is held with 8 grub screws. pull the cap off and loosen screws. adjust so you have magazine clearance. Tighten down, re install cap cover, and enjoy!