[Best 40 S&W brass]

Starline is probably the best but if you want to pay less and get a well made brass go with GBW.

[GBW brass]

I've loaded 1k or so of 9mm, .40 and .380 with GBW brass. I can honestly say they are very consistantl for weight and dimensions and all have cycled great.i get them from midsouth. A great place and service too!

[COL differences]

Okay, I will be loading some once fired soon and will do that. 

Are you saying that the brass can basically spring back on certain brands and cause this difference in COAL? Just a thought

[COL differences]

You guys are stating that it happens and different sizes etc. But you aren't telling me why. COAL is from the bottom of the case to the top of the bullet. The bottom of the case is always touching the bottom of the plate, whichever type plate that is. And then the bullet is pressed in the casing to an adjusted stop position. Even though case sizes have different thicknesses they are all expanded by the same expander. 

To me the only thing that effects COAL is bullet shape or inconsistent press stroke

[COL differences]

Are you also saying this large variance will happen when seating FP bullets with the FP seating stem?

[COL differences]

I don't see how different brass would make a difference? Maybe someone can explain. What type of bullet are you using? RN, HP. FP? I know on FP and HP I get about a .002 variation but with RN, the oglive of the bullet isn't always the same and COAL will vary.