Are there more than one optimal seating depth fore a 223 bullet?

[jlow]

Gstaylorg – sorry but it looks like we cross posted.

Yes, agreed, it does look like the effect of seating depth on precision is cyclic in nature. However, the cycle in my case seems to be pretty short in nature – only around 10-12 thousands? Since I started at COAL of around 2.396” and SAAMI is 2.260”, there is a long way (136 thousands) to go before mag length, but I am sure I will run into pressure problem with this load long before since it is pretty hot.

Here are two plots - seating depth against SDEV and seating depth against MOA. The cyclic nature is identical.

 

[amlevin]

For the OPs original question, seating depth is all about barrel timing.

True but it's also my belief that varying seating depth with the same powder charge can also enhance or detract from the ideal "burn" of the charge. Sort of the same principle as how some powders perform better when the case is full versus some percentage less than 100%.