There are times when I think folks get confused over these two issues.

The difference between OAL and seating depth.

Some will ask: "Aren't the two the same thing?" To which I reply: "No."

When asked to explain I usually use this photograph:



While both of these bullets are of the same caliber and weight one can readily tell that they both have different lengths. When loading these bullets you can attain the exact same OAL but which one is going to have the deeper seating depth?

It may not matter in the low pressure 45ACP round. One thing for sure though, it will in the 40S&W that is being fired in a "Tactical Tupperware" or anything else with an unsupported chamber. Now just to dispel any rumors that you might take from that statement, I love my G22 RTF and handload for it for every occasion.

So OAL does matter but more importantly bullet seating depth. It plays a much more important role on pressures than does anything else. That information is taken from an older Speer manual where they did actual tests on the subject.

That brings us to another situation that crops up. "What do I do when I can't find a recipe for the EXACT bullet I have?"

Like this:


One can see that the same OAL is attainable with either bullet but which one will have more of it in the case? Which one will have the lower pressure using the same amount and type of powder? Well, unless the bullet is jammed against the rifling, the one with less seating depth.

By the way, this is the whole principle of Elmer Keith's bullets.

Just a thought.