tight necks lapua brass
- Thread starter tickridge
- Start date
I always run a expander mandrel through the necks of new brass to get necks closer to proper tension.
Are you meaning that your seating pressure feels higher than normal?
Two things can be at play:
Neck Tension
Seating pressure
At times they are congruent and others they are independent from one another.
If you run a mandrel and/or verify with pin gauges that the neck tension is where you want it and it is still feeling tight, then you have a friction issue.
Some moly or one shot spray on a swab inside the neck will usually alleviate the issue.
For experimental purposes, take brand new brass and a hydropress.
Use mandrel/pins to verify the same neck tension on the brass.
Seat some bullets in the bare brass. PSI will be >80
Now take some moly or one shot or any other lubricant and wipe inside the necks. Your PSI will drop to 60 or less.
Two things can be at play:
Neck Tension
Seating pressure
At times they are congruent and others they are independent from one another.
If you run a mandrel and/or verify with pin gauges that the neck tension is where you want it and it is still feeling tight, then you have a friction issue.
Some moly or one shot spray on a swab inside the neck will usually alleviate the issue.
For experimental purposes, take brand new brass and a hydropress.
Use mandrel/pins to verify the same neck tension on the brass.
Seat some bullets in the bare brass. PSI will be >80
Now take some moly or one shot or any other lubricant and wipe inside the necks. Your PSI will drop to 60 or less.
Not sure which die you’re using, but just lube the case up on the inside of the neck and run it over the expander ball and back.
I think Lapua inside chamfers are frequently off. It’ll seem like it’s ok, but the bottom edge has a burr on it which grabs the bullet.
I think Lapua inside chamfers are frequently off. It’ll seem like it’s ok, but the bottom edge has a burr on it which grabs the bullet.
Just make sure you’re not sacrificing tension for less friction.
Example, you can have two cases sized exactly .002 under the inside diameter for .002 neck tension.
One may seat at 80 psi without lube/moly. The other seats at 30psi with lube/moly.
A lot of people end up using oversized mandrels because that’s what it takes for the bare case to get down to 30 psi. Yet now they are running .0005 or less neck tension and their chrono results aren’t consistent.
Example, you can have two cases sized exactly .002 under the inside diameter for .002 neck tension.
One may seat at 80 psi without lube/moly. The other seats at 30psi with lube/moly.
A lot of people end up using oversized mandrels because that’s what it takes for the bare case to get down to 30 psi. Yet now they are running .0005 or less neck tension and their chrono results aren’t consistent.
