I did not fully trust the measurements I was obtaining when trying to determine the exact COAL on my 260 bolt gun. I then used a Hornady OAL gauge, but drilled and tapped the base of a SMK 142 to 10-24. I used the threaded rod in place of the plastic Hornady rod.
The photos below show the system, which should be very accurate. Only problem is that my COAL measures 2.975, which is longer than expected. Any comments welcome.
The mags I am using are Alpha Type 2, which are 2.985 ID. If I used AI mags, I would have to reduce the COAL to approximately 2.875.
The photos below show the system, which should be very accurate. Only problem is that my COAL measures 2.975, which is longer than expected. Any comments welcome.
The mags I am using are Alpha Type 2, which are 2.985 ID. If I used AI mags, I would have to reduce the COAL to approximately 2.875.

