Boolit lube left over in case mouths

[Lefty SRH]

I have a 6 1/2” SBH Bisley in 480 Ruger. Ive noticed that the extracted cases have a good bit of bullet lube on the case mouth. I have also notice some lube stuck to my target down range that usually between 25 and 50yds.
Question is why is my bullet lube on the case mouth?
The current bullet is a MP 477-640 over H110 or HS-6 both with mag primers.
Is this a problem? If so how do you fix the issue.

I dont remember seeing this in my 480 SRH and I know it doesnt happen in any of my other guns.

[Lefty SRH]

Has this stumped you guys?

[243winxb]

The gap from case mouth to chamber throat collects lube . On my 357, the 50/50 almost looked like extra long brass, except lube is a different color. Only on a few, not all.

As far as lube on target, the blue & red stuff can be found on bullets recovered from the berm. Some lube is thrown off as the bullet spins. It cant be good for accuracy? Can it?

If happy with accuracy, i dont see a problem.

The fix? Try a different lube?

[243winxb]

The red line is where lube may collect? More so if brass is on the short side? My guess.

.023" gap from case mouth to throat.

[bmortell]

ive done testing with boolits with 1/3 the circumference of lube removed to simulate a lube that don't fully eject quickly and measured 50% increase in group size at 25yds. so if your still ejecting sporadically down range id go softer lube.