Seating depth

[mdi]

Lately I've noticed a few threads on bullet seating OAL, and I got to thinking. In my text "Complete Guide to Handloading" by Sharps all the seating depths seem to be depth of the bullet's base, rather than OAL. For example a 45Colt with a 250 gr. "Factory lead" bullet over a 9.0 gr. charge of Unique the bullet seating depth is noted as .285". In 9mm with a 124gr MC bullet over a 4.8 gr. charge of Bullseye the seating depth is .175". Seems to me that this was the standard method of bullet seating before the easier OAL method became the standard (and added different methods of measurement, and a bit of concern).

If I were to go into depth for seating depths in my handloading, I would, with a bunch of research and measuring determine how deep the base of a specific bullet should be seated into a case. I understand that seating depth can be worrisome for many newer reloaders (as seen by the many concerned questions about OAL for their 9mm handloads).

In 40+ years of reloading I cannot remember any seating problems, mainly by my using bullet manufacturers data. But I believe the old, no longer used method of seating by bullet base depth is more accurate, would remove any speculation or worries about depth/OAL vs chamber pressure...

 

[GeoDudeFlorida]

Lately I've noticed a few threads on bullet seating OAL, and I got to thinking. In my text "Complete Guide to Handloading" by Sharps all the seating depths seem to be depth of the bullet's base, rather than OAL. For example a 45Colt with a 250 gr. "Factory lead" bullet over a 9.0 gr. charge of Unique the bullet seating depth is noted as .285". In 9mm with a 124gr MC bullet over a 4.8 gr. charge of Bullseye the seating depth is .175". Seems to me that this was the standard method of bullet seating before the easier OAL method became the standard (and added different methods of measurement, and a bit of concern).

If I were to go into depth for seating depths in my handloading, I would, with a bunch of research and measuring determine how deep the base of a specific bullet should be seated into a case. I understand that seating depth can be worrisome for many newer reloaders (as seen by the many concerned questions about OAL for their 9mm handloads).

In 40+ years of reloading I cannot remember any seating problems, mainly by my using bullet manufacturers data. But I believe the old, no longer used method of seating by bullet base depth is more accurate, would remove any speculation or worries about depth/OAL vs chamber pressure.

Measuring and recording average bullet lengths, diameters and weights is just part of handloading. Measuring where a bullet lands in each firearm’s chamber and comparing it to the seating depth needed to keep a proper headspace over the powder column is a step farther than most people are willing to go, for some reason. I do it but I know few who do. Likewise, I see and hear a lot about keeping assiduous records - every target, every step of load development, the temperature and atmospheric conditions the day a set of velocities were recorded, etc. - but almost no attention is paid to the volume of the powder column, the air space left after bullet seating, changes in the seating depth from book values, and such. I see a LOT of assumptions being made that EVERY XXXgr bullet is identical, when they clearly aren’t.
I think it’s an important topic but i’m In the barest of minorities.