Boolit setback using Lee FCD with 311291's

[fremont]

I'm loading 311291's in a 300 Savage. Lyman boolit manual says 2.358" COAL. Given the dummy round I'd earlier constructed to ensure functioning, I noticed a boolit setback of approximately .015". So.....I seated at around 2.373". I adjusted the Lee FCD to apply a proper crimp (mouths were belled prior to boolit seating), and--lo & behold--I get setback of .025"-.030" down to around 2.345" (similar to what I'd seen with the dummy round).

Is it a function of the crimp groove, meaning that when a crimp is applied the brass is going to "pull" the boolit down until the crimp conforms to the boolit/crimp groove shape?

I'm not particularly worried about a shorter-than-specified COAL, as I'm not expecting my newly acquired M99 to be a tackdriver, but I am interested on whether I should give up trying to stick an exact COAL when crimping cast boolits.

[M Hicks]

The Lee FCD is designed to push the case mouth in perpendicular to the center line of the bullet. It should not be shortening your OAL.

You may have the die adjusted too deeply and it is applying a crimp and holding the cartridge while your press still has a slight amount of movement on the rams upstroke. When the press cams over you might be applying a slight amount of excessive movement that causes the OAL to be affected.

Try backing the FCD die off a little. You will still get plenty of crimp to perform the way you want but it shouldn't change the OAL.

One other issue is that all brass needs to be trimmed the same length to get repeatable crimping with those dies.