Flat primer question

[Tenntrapper]

What will cause flat primers?
Got a rifle from another member. Fired some factory ammo...primers are flat. Started loading for it...starting loads are flat. (No other signs of over pressure though). Full length sized the brass...load again...flat primers. Got a neck sizer. Sized once fired and loaded again...flat primers. Thought maybe the headspace was off... Just got in today a field gauge...bolt won't close on it.
This is new Lapua brass BTW...and I've tried 3 different bullets/loads. All loads were measured to the lands with the Hornady length gauge...and seated .020-.025 off the lands.
What am I missing?

 

[nso123]

What is the cartridge? How many rounds have been fired through it? Could possibly be a carbon ring.

 

[Tenntrapper]

What is the cartridge? How many rounds have been fired through it? Could possibly be a carbon ring.

6.5 Swede
No idea on rounds fired

 

[Iroquois]

Have you checked that your load data is correct? Powder, primer, case length, etc.?

 

[Tenntrapper]

Have you checked that your load data is correct? Powder, primer, case length, etc.?

I've checked multiple sources. Also, as I said, it does the same thing with factory ammo.

 

[Lt.Dan]

You might need the chamber worked. It sounds like you are on the money with the headspace thought.

 

[nso123]

I would scrub the throat really good with some carbon cleaner. If the headspace is checking good, I'd be looking at either a short throat or a carbon ring.

 

[Tenntrapper]

I would scrub the throat really good with some carbon cleaner. If the headspace is checking good, I'd be looking at either a short throat or a carbon ring.

I've spent the morning scrubbing the throat and barrel. I used the oal gauge again and am getting an extra .005" now. No idea if that's enough to make a difference..but I'm about to load one and try it.
Will update in a bit.

Edit to update...
Looks like it made a difference. Both are same loads...one on the left was the way it was, the one on the right is after scrubbing.
Thanks for the help..

 

[Wiley]

And I learned something here

 

[MUP]

Carbon ring, the struggle is real!

 

[Iroquois]

And I learned something here

This^^^^^^^^^
Me as well!

 

[DaveB]

Foam cleaner solves the ring issue.

I get flat primers moving from 58 to 59.5 gr of IMR4350 30/06 150 gr Noslers. Same thing with bunches of other powders/calibers.

Since the increase in powder charge has a noticeable positive change in group size, I long ago decided to not worry about flat primers. I want Accuracy and many times I see a max charge plus a small few tighten up the groups.

And I use lots of foam cleaner.

 

[nso123]

Foam cleaner solves the ring issue.

I get flat primers moving from 58 to 59.5 gr of IMR4350 30/06 150 gr Noslers. Same thing with bunches of other powders/calibers.

Since the increase in powder charge has a noticeable positive change in group size, I long ago decided to not worry about flat primers. I want Accuracy and many times I see a max charge plus a small few tighten up the groups.

And I use lots of foam cleaner.

I'm like you. I don't get too wadded up about a flat primer. In this case, the flat primer he was getting with factory ammo would make me investigate though. I have found some loads that tighten up all the way to a sticky bolt. That's beyond my risk tolerance though.

 

[DaveB]

Sticky bolt and I unload the ones i inched up too far.

In my book this is your sure sign you are too hot. I did 50 223 62 gr--was sure of my charge weight--- could not crank the bolt. No more of that. 5 at a time.

 

[MUP]

Flat primers and a hard bolt lift would seal the deal for me to either back off the load or check the chamber.

 

[rickyk280]

Flat primers and a hard bolt lift would seal the deal for me to either back off the load or check the chamber.

Hard bolt lift and I will back off. Flat primers don't worry me. I have a 30-06 I been using H4350 it's been flattening primers for nearly 40 years, it shoots that load too good to mess with.