The mans question seemed to be 'how to check headspace WITHOUT gauges'. When I was in gunsmith school we were told that Remington ammunition was generally sized to minimum standards and Winchester was sized to maximum. To headspace using a new factory loaded round,pick Remington. Remove the cocking piece /firing pin on the rifle renedering it as safe as possible. Insert the Remington loaded round and gently close the bolt. Resistance should be felt about 1/8"-1/4" before fully closed. This would be considered near minimum headspace. Have no idea that this still applies to Remington ammo. Without any doubt the only PROPER way is with the correct gauges. I used this method only once to check a 6.5x54MS that I had no gauges for but did have some factory loaded rounds except in this case they were RWS. Again I would state - THE ONLY PROPER WAY IS WITH THE PROPER GAUGE
