.223 seating issue need help

[NY700]

I'm running RCBS competition dies with the micrometer seater w/window on a rock chucker. Full length sized brass with 77gr SMK. I'm feeling a lot of tension when seating and it appears to shave just a tiny bit of the jacket so after its seated I can run my nail around it and pul off a small ring of copper from the bullet. I used my calipers and measured the inside diameter after sizing it and it measure .221. My sizing die is set to manufacturer directionsand I've played with setting it a litle deaper and shallowerwith no real change. Inside and outside of the case mouth is debured nothing excessive. I've used my. Way cutter and also a wilson hand camer tool with no real change. The case mouths are smooth and clean and not excesivly sharp
Any ideas would be great

 

[Borg]

Re: .223 seating issue need help

Check the mouth of the case to see if there is a raised ridge below the inside chamfer.
Depending on how hard or the tool itself, it can leave a ridge inside, and it will shave copper.
Use a 10X loupe to check, eyes sometimes miss it.
Borg
ETA if you tumble the lube off, check to make sure the mouths aren't peened inward.

 

[NY700]

Re: .223 seating issue need help

Ill double check the camfer but I preity sure that's not it as I'm having no problems with any other caliber, and it is leaving a perfect circular ring of copperat the top of the case mouth that I can just peal off, so I guessing it hasto be something with my dies

 

[Borg]

Re: .223 seating issue need help

Pull your expander ball out of the sizer and measure it, that could be a problem, if correct, look elsewhere.
If chamfered, then the first thing that touches the bullet would either be a ridge inside that would shave, or the neck that wouldn't, assuming the expander is correct.
Borg

 

[gunsnjeeps]

Re: .223 seating issue need help

Sounds like inside chamfer to me. You might need to chamfer just a bit more. I had a similar problem, my chamfer cutter slipped (3 wad cutter) and didn't do the inside of my last batch of brass. About 400 pieces. I get exactly what you describing from the boattail transition of a Sierra Match Kings if I don't have enough chamfer. When you set the bullet on top of the neck does it cup into the chamfer and sit straight up or sit on top of the neck and kind of balance and flop easy? .221 sounds like good tension. Have you measured two ways, 12 to 6 and 3 to 9 to make sure your necks are round?

 

[cooper_257]

Re: .223 seating issue need help

get a VLD chamfer tool, it should fix your problem.