1)  Which is the correct term for using a Lee tool on the outside of the case mouth?

2)  Which is the term for the inside of the mouth?

3)  I primarily load cannalured boolits, but in either case, for accuracy's sake, I am thinking that this case prep step can only have a negative affect on accuracy.  There is no way I am going to remove a uniform amount of material from the case mouth.  That results in inconsistent crimp pressure and different release of the boolit each time?  What say ya'll?

4)  With cannalures esp. I think it may be best to leave them unchamferred, to get a better more solid purchase on the cannalure's slot.  Thoughts?

 

I am using Dillion Dies. for 223 and 308.  I believe these are both taper crimps.


If there is variation on the remaining mouth material, is it not reasonable to expect variations on results?  I am not using expensive enough projectiles, usually, that I think I could detect the differences.  I am looking to this down the road and I am just looking to gain some knowledge.

I am using a Dillon trimmer as well.  The giraud I guess chamfers as well?

Thanks for your assisstance.

Just a light touch is all that's needed.  We're not trying to create a knife edge.

I have been way overdoing it.  It is sharp enough on both in and out to cut you.  I'll try to stop dat.

Thanks guys.

You should barely be able to see a line of cut brass from deburring.

Chamfering would be a little larger, and aids in getting flat base bullets started without snagging the case mouth.

New Lapua Match brass is chamfered and deburred and it barley has the edges rounded to make both sides smooth so the case mouth doesn't cut the bullet jacket when seating. Try seating a Barnes TSX bullet without chamfering the case, there will be a pile of copper dust on top of the case mouth where it scratched the bullet jacket all the way in and this is with the 62 & 70gr bullets which are boat tail. I have to "lightly" VLD chamfer the brass I use for loading Barnes bullets to prevent this since even a regular chamfer tool doesn't cut enough angle to prevent the jacket scratching.

ETA: This is three pieces of PMC range pickup brass I had just finished prepping.

Thanks for improving my results, gentlemenses!