Significant increase in seating pressure..... why?

[Mulligan]

Yesterday i loaded some 284 ammo for my f class rig.
When i started seating bullets the force needed was crazy.
I use an K and M arbor press and wilson dies.

I used the same brass the day before and it required around 20 pounds of force to seat the bullets. They seated smooth as a hot knife in butter.
Yesterday the force needed was all over the place with several nearing the 100 mark. No changes to dies or bushings at all. What causes this?
CW

Edit
By the way
The target at 600 didn’t like this change at all ....... lots of vertical.
CW

 

[Capt. Oblivious]

Can you drop a bullet all the way down the neck into the case on one off those piece of fired brass?

 

[davidpatton]

Were these pieces tumbled with the ones from the previous day? How about the chamfer inside the neck, were both groups of brass done with the same tool? I have see issues before where my chamfer tool had created a burr, or certain tumbling media would create inconsistent seating force.

 

[Mulligan]

Can you drop a bullet all the way down the neck into the case on one off those piece of fired brass?

Of the 10 i checked, two dropped in and hung up on the donut, three were a little tight and five dropped right in once aligned.
The rifle has a .313 neck and the Lapua Brass is turned to .012 for a 308 loaded round.
CW

 

[Mulligan]

Were these pieces tumbled with the ones from the previous day? How about the chamfer inside the neck, were both groups of brass done with the same tool? I have see issues before where my chamfer tool had created a burr, or certain tumbling media would create inconsistent seating force.

No tumbling, just wiped them off and went about my business. I always use oooo steel wool on the mouth of the necks after trim or chamfer.
CW

 

[dkhunt14]

Did you size them and let them set? Matt

 

[Mulligan]

Did you size them and let them set? Matt

No Matt, I sized and loaded yesterday morning.
CW

 

[Ringostar]

What bullet are you shooting and what is the free bore of your chamber? I've been having doughnut issues with my 284, loading 180 Scenars.

 

[Richard Coody]

What bullet are you shooting and what is the free bore of your chamber? I've been having doughnut issues with my 284, loading 180 Scenars.

when did you anneal last?

how many firings on the brass?

might want to size them tight and use an expander mandrel and run your neck turner again. it will get rid of the donuts and thin that thickened shoulder brass that is migrating into the neck.

 

[geraldgee]

An obvious question - Have you changed bullet lots or checked bullet diameter?

Good luck

 

[Mulligan]

What bullet are you shooting and what is the free bore of your chamber? I've been having doughnut issues with my 284, loading 180 Scenars.

I am shooting the 180 Berger hybrids, don’t recall FB but is is such that the bearing surface/boattail junction is well above the darn donut.
I was having all kinds of trouble with vertical with this rifle until I tested neck clearance. That proved to be very helpful. With .0045 or more clearance the vertical went away.
Interesting, .003 clearance if you you only looked at group size

when did you anneal last?

how many firings on the brass?

might want to size them tight and use an expander mandrel and run your neck turner again. it will get rid of the donuts and thin that thickened shoulder brass that is migrating into the neck.

This brass has 4 firings and has not been annealed.

I turned them again after the second firing. Yes the donut area was the thick spot for sure.
CW

 

[Mulligan]

An obvious question - Have you changed bullet lots or checked bullet diameter?

Good luck

No change is lots.
Bullet diameter is .284 with ~.001 increase at pressure ring.

I really do not think it is the bullet, as they loaded fine every other time.
I think it is a brass issue.
However, just to be clear, i am open to all info as this has me perplexed.
CW

 

[Ringostar]

I had 2 firings since annealling a year ago. I just went back through them with a mandrel and returned them to get ready for Phoenix. One more firing and it will be time to retire the barrel and brass.

 

[Mulligan]

I had 2 firings since annealling a year ago. I just went back through them with a mandrel and returned them to get ready for Phoenix. One more firing and it will be time to retire the barrel and brass.

What is a norm for brass life in a 284 used in f class?
This is a new clambering for me.

I have shot a dasher for the last 2 years which is my only real experience with guns that will shoot small....... love my Dasher.
CW

 

[Ringostar]

That depends on how hot your loading them. Primer pockets can loosen rather quickly if you push them. I consider 6 firings good. If you start a new barrel with 300 pcs, and get 6 firings that puts you at 1800 which is typical barrel life of a 284.

 

[Mulligan]

Orange holes, .301 bushing Blue holes .305 bushing

 

[Mulligan]

Using the .301 bushing, i tried three different mandrals. Red (.279) showing just over 1” vertical at 600 yards. The nice thing is the whole test is decent for f class..... a bit of forgive in the system.
Now its time to prove the load.
CW

 

[Mulligan]

Yesterday’s groups with the very hard bullet eating issue.
This is two different mandrals, 5 shots each. Same load otherwise.
I will anneal and shoot again tomorrow.
Thanks all.
CW

 

[Mulligan]

That depends on how hot your loading them. Primer pockets can loosen rather quickly if you push them. I consider 6 firings good. If you start a new barrel with 300 pcs, and get 6 firings that puts you at 1800 which is typical barrel life of a 284.

That’s good info.
I am running right at 2850, primer pockets are holding up great.
Sounds like i need to anneal more often
CW

 

[Mulligan]

That depends on how hot your loading them. Primer pockets can loosen rather quickly if you push them. I consider 6 firings good. If you start a new barrel with 300 pcs, and get 6 firings that puts you at 1800 which is typical barrel life of a 284.

Are you running a tight neck?
if accuracy allows, a no turn would be way better. Turning is time spent in the loading room and not shooting.
CW