220 Swift case issue

[Bruce Mc]

I have a new lamp on my reloading bench with a large magnifying glass and on my last batch of fired 220 swift brass I noticed an irregularity on the tip edge of the neck. It appears that the first hundredth or so is tapered after firing. I can't say for sure if this has been occurring all along or if I just noticed it. What could cause this, the bullets were not crimped. Any idea?

 

[JD338]

Interesting. Maybe some carbon buildup in the chamber?

JD338

 

[300WSM]

Question...

Did you trim these cases at any point before?

It sure looks to me as it's some remaining type chamfer

 

[filmjunkie4ever]

Maybe your throat is just a bit short and the cases are a bit long?

 

[Bruce Mc]

These were new cases that I neck sized and deburred and i.d. chamfered. After firing they're still shorter than max.

 

[Bruce Mc]

Interesting. Maybe some carbon buildup in the chamber?

JD338

I'm gonna give the throat an good scrubbing with a carbon remover and see if it repeats.

 

[RL338]

Do you trim to the shorter side?
Just a guess that the new brass is longer and being pinched by a carbon ring as other have mentioned.

 

[NYDAN]

Although it is unlikely, if you think the chamber neck might be too short, you could check the length of the chamber neck with one of these: https://www.brownells.com/reloading...s/sinclair-chamber-length-gage/?sku=749000811

 

[Bruce Mc]

Seeing as the necks are always blackened after being fired I'm leaning on fouling. I'll get back after I give it a good scrubbing and shoot some more.

 

[300WSM]

Maybe your throat is just a bit short and the cases are a bit long?

If what you're suggesting is going on I would think the OP would definitely notice a different feel upon chambering loaded rounds

These were new cases that I neck sized and deburred and i.d. chamfered. After firing they're still shorter than max.

You didn't deburr thr O.D.? A lot of those tools do both

 

[300WSM]

Something going on there...

 

[SJB358]

Seeing as the necks are always blackened after being fired I'm leaning on fouling. I'll get back after I give it a good scrubbing and shoot some more.

Let us know what you see after the cleaning. Looking at the pic, I can’t say I’ve run across this.

 

[Bruce Mc]

Let us know what you see after the cleaning. Looking at the pic, I can’t say I’ve run across this.

Scotty that little taper mics out at 005" at the tip less than the neck. It goes away when the case is resized.

 

[jimbires]

something else to look at .

are you crimping ? if not , I'd check the die setting to be sure the body is high enough to not touch the brass case , when seating a bullet .

I don't crimp any rifle ammo , I'm not sure what it looks like after being fired .