9mm Shells Have Burn Marks???

[implicit455]

Why am I seeing burn marks on about 1/3 of each fired shell? Loaded 4.0,4.1.and 4.2 grains of Bulleyes,115gr Hornady HP w/CCI 500 primers. Five with a light crimp and 5 a little harder crimp all in the cannelure section which gave me a COL of 1.110". Also, the 4.2 load shells would not eject. Try factory loads after that and they all ejected??????? strange.

 

[Aguila Blanca]

I don't load Bullseye -- is that a light load? If so, it's TOO light ... there isn't enough pressure to expand the case mouth far enough to seal against the chamber wall.

 

[chris in va]

The Alliant site shows 4.7gr under a 115gr GDHP at 1144fps.

My Lyman manual shows a 115gr JHP 3.5-4.8(max), which seems to me you have a middle charge. It should cycle the slide, but you may want to try some 4.5's.

 

[lee n. field]

Loaded 4.0,4.1.and 4.2 grains of Bulleyes,115gr Hornady HP

You're solidly in the middle of the published range. Lyman's 48th is showing 3.5 to 4.8 grains of Bullseye for 115 JHP.

"Burn marks" would suggest to me that you don't have the internal pressure to make the case swell enough to seal the breech end, and are getting gases blowing down the outside of the case.

Any way you can double check your powder charge, that what you think it 4.x grains, actually is? Check weights for the scale?

(BTW, I'm using 3.8 grains of Bullseye behind a 120 grain cast lead bullet. That's bottom of the range for that bullet per Lyman, and it's working just fine.)