Headspacing before you remove the barrel is a good idea. I had three I/O non matching kits and headspaced all three. Luckily they all were within specs.sharky47 said:Title pretty much says it, wondering if a headspacing in in order on my East German AKM parts kit with non-matching part #'s. I plan on removing the barrel to completly remove the old rivits, but will probably put it back together with screw. TIA!