Please answer this...

[NoahbodyImportant]

Is this normal or is this a sign of a worn throat?

I have once fired LC 69 Match brass (.308) it measures .343 at the top of the neck.

I neck size the brass using .336 TiN bushing and it now measures .333

With a 155gr (2156) Palma bullet seated measures .333

Now fired measures .343

Expanding .010, is that normal or excessive?
Am I using the wrong size neck bushing?

Am I ok, or is the throat worn out?

Much Appreciated.

 

[Teggy1]

so, zero neck tension?

 

[ChrisGarrett]

Is this normal or is this a sign of a worn throat?

I have once fired LC 69 Match brass (.308) it measures .343 at the top of the neck.

I neck size the brass using .336 TiN bushing and it now measures .333

With a 155gr (2156) Palma bullet seated measures .333

Now fired measures .343

Expanding .010, is that normal or excessive?
Am I using the wrong size neck bushing?

Am I ok, or is the throat worn out?

Much Appreciated.

My Savage 10FP blows my necks out to .343"-.344", so nothing unusual there.

You're sizing down more than .005"in one pass, so you might be losing some springback, which is why I use a step down bushing, like a .340"--.340">final sizing bushing.

Still...I would think that .335" would be the worse you would see. You sure you're using a .336" bushing with numbers pointing down in the die?

Your brass is old and maybe the necks are harder and/or it needs to be annealed, even though it's 1x?

I don't know what kind of calipers you're using, but most 762/308 brass has neck walls in the neighborhood of .014", so double that and we get .028", add .308 and we get .336", so if you're measuring .333 loaded, you getting .003" of constriction on the bullet, as long as the average neck wall thickness is .014" per side. Anything less and constriction will be less.

Yes, blowing the case mouth diameter out ~.010" is 'more' normal with factory barrels, than it is obviously with tight match chambers.

Chris

 

[milo 2.0]

Is this normal or is this a sign of a worn throat?

I have once fired LC 69 Match brass (.308) it measures .343 at the top of the neck.

I neck size the brass using .336 TiN bushing and it now measures .333

With a 155gr (2156) Palma bullet seated measures .333

Now fired measures .343

Expanding .010, is that normal or excessive?
Am I using the wrong size neck bushing?

Am I ok, or is the throat worn out?

Much Appreciated.

The throat and the neck are seperate things, the neck is considerably larger than the throat and really don't have much to do with the other.
The bore or throat goes down to .308,the throat is the angle to .308, the neck is reamed at .343".

.010" is quite a bit for expansion, that's like .005" per side. If your sizing with a bushing die, you'll have a outside donut in short order.
You'll notice throat erosion by bullet seating depth.

 

[NoahbodyImportant]

bolt action, Parker Hale 1200TX chambered 7.62x51 NATO