I've never had this issue. It's extremely hard to seat a bullet....


.308

All Lake City Brass, FL sized. Not trimmed, it doesn't need it yet.

Bullet: Hornady 150gr FMJBT w/cannelure, not pulls, not 2nds. A random sampling measures .3065-.307 measuring between the cannelure and boattail.

After sizing, the case mouth measured .305. It was impossible to seat abullet without shaving it. So, I ran some through my 21st century mandrel that measures .306. Still shaving bullets and extremely hard to seat.


I could ALMOST understand this issue if it wasn't a boat tail.

The only thing I haven't done is chamfer the inside of the case mouth.
That shouldn't be necessary with a .3065-.307 boattail bullet going into a .306 case mouth.

Thoughts?

Have you chamfered the case mouth?

Inside chamfer. Other thought is hardness of the brass. Neck annealing would soften but a lot of trouble.

Another thought would be brushing necks with powdered mica or other dry lube

Chamfer is the only thing I haven’t done.

The necks have dry lube on them from me running them over the mandrel. That’s another reason I can’t make myself believe a chamfer would be needed at this point

Chamfer.

Also, the neck will be slightly smaller than .306 when using a .306 mandrel due to brass spring back.

Always chamfer. Why would you chamfer?

Are you wet tumbling your brass with pins? If you are it's peening the case mouth stop tumbling and chamfer then mandrel.

Get a 4 lb hamm..no nevermind chamfer instead.

Ok Grandpa!!! That was his solution for most everything. Get a bigger hammer!!

Chamfering is going to be a good chore for my son tonight.

The peening of the case mouth is a real possibility. These were cleaned before I stopped using pins.

I can definitely tell when I miss a case while chamfering. It lets you know real fast.

If the cases have been been sized / loaded more than 3 times, anneal the necks. Easy to do with a candle. PM me if you’d like details.
Anneal 5 cases and see if problem goes away.

A candle you say? I'd do some more research on how to anneal if I were you

A small propane torch and a socket on a drill/driver makes for fast easy annealing

Yep that's all you need really that's how I started and a bottle of Templaq

This works great and is cheap.

I once wasted 10 minutes trying the candle method...

And if I were you, I’d Google “John Barsness candle annealing” and read and learn something.

Folks, the amount of heat needed to anneal a brass case neck is not great. It doesn’t need to be red hot. Brass anneals at 750 degrees F and a candle tip gets 2500 degrees F.
For those unwilling to research…. Hold the case at the middle while rotating the neck in the blue tip of the candle flame. Once the case is too hot to hold, drop it to be air cooled. Wipe neck with a damp cloth to remove soot. Cold water dunking is not needed when candle annealing. Considering I’ve done about 300 cases by this method, I know it works. It was developed by a metallurgist, Fred Barker.

Keep doing what you do then I'll keep time to temp and time at temp that's required to properly anneal

I've read it and tried it.

Torch with a cordless drill and deep socket is MUCH easier.