Using .45acp brass to measure .308 shoulder setback

[silicosys4]

I have a .308 that seems to require a lot of shoulder setback to chamber. Reloaded rounds don't chamber easily unless they have been sized with the sizing die screwed down in the press to the point that the press cams over hard against the die.

I was looking for a way to measure how much i have to set the shoulder back as I wait for my gauges to arrive, and found this neat trick to get a quick measurement using a sized .45acp brass.

http://bulletin.accurateshooter.com/2007/07/tech-tip-poor-mans-headspace-gauge/

 

[MtnCreek]

Off memory, I think .400 is the bushing I use for .308 win. I think .420 is what I use for .300wm.

Shoot a .40 s&w or 10mm?

 

[MarshallDodge]

I have heard that a .40 case is what you want to try for this purpose but have not tried it myself since I have the Sinclair tools.

 

[Ifishsum]

I use a .40SW case for 308/.30-06, as it will be close to the actual datum reference point. I keep one in the die box so I'm using the same one when checking shoulder setback.

 

[gamestalker]

I've done this before, I imagine it isn't the most accurate way of measuring shoulders, but it does work. I've belled .40 cases so they will have a nice fit over the shoulder. Making sure they are evenly trimmed and smooth mouths helps too.

GS