Powder Residue: 1911 vs Revolver

I've noticed heavier loose powder-ash residue in spent cases from my 9mm revolver than the RO9.   The particles are ash-like and I'm guessing an incomplete burn caused by less blast restriction in the cylinder gap and the forcing cone.  At first I thought the ejection and subsequent impact of the RO's spent cases emptied them of the loose residue.   I could not find any by laying a white cloth in my brass catcher.   This happens with both Titegroup and BE-86 along with light and near-max loads in the revolver only.   The residue is visible in the cylinder throat and falls out of the spent cases when tapped on the head, mouth down.   Does anyone have insight into this phenomenon?

I have noticed this as well. I suppose that its about the initial resistance experienced by the bullet. In the revolver, the bullet has about an inch of no or little resistance before the bullet contacts the rifling. The pistol has much, much less distance before bullet contacts rifling. The pistol may get a better "burn" because of this.

I would only consider this a problem if its causing function problems when the residue gets under the ejector star. If your desired accuracy is there, don't worry about it.

So I'll guess that my supposition of less restricted gas expansion is the cause of "revolver (r)ash" in the cylinder throat and spent cases.