Weird sizing / seating issue

[GetReal]

So I'm loading 300 ham'r, which is basically a 30 caliber AR15 ... Bill Wilsons creation.

I'm sizing the case on an RCBS rock chucker with an RCBS die.

But i'm charging And seating the bullet on a Dillon 550C. Trying to mass produce.

Of course, the bullet diameter is 0.308. The sizing die gives an inside neck of 0.298.

But then when I try to seat the bullet, The neck tension goes to 0 and I can physically spin the bullet in the case.

  From the picture it looks like the
Case neck is flaring out and mushrooming.

I have tried threading the die in and out and moving the seating SStemin and out but nothing seems to fix the problem. I don't think the die is crunshing the case... But something is causing the Case neck to expand to 0 neck tension.

is the neck inside being 0.298 vs. the bullet being 0.308 Putting too much Pressure on the neck when seating the bullet?


Any ideas ?

 

[Allen Corneau]

No actual experience in this department, just postulating, but...

Is it possible that in expanding the neck from .223 to .308 you've thinned out the neck material to a point where it's just collapsing when you seat the bullet?

Any chance you can get a semi-accurate measurement on the neck wall thickness? I'm guessing it's pretty thin.

 

[GetReal]

No actual experience in this department, just postulating, but...

Is it possible that in expanding the neck from .223 to .308 you've thinned out the neck material to a point where it's just collapsing when you seat the bullet?

Any chance you can get a semi-accurate measurement on the neck wall thickness? I'm guessing it's pretty thin.

Its factory 300 Hamr brass. (Starline)

 

[Bill Norris]

Its factory 300 Hamr brass. (Starline)

What brand is the brass?

 

[GetReal]

So I had a few pieces of Virgin starline brass and their inside neck measures. 0.306 ....and they seated fine.

 

[SeabeeKen]

.010 neck tension seems a bit excessive to me but then ive never tried a 300 hammer

 

[ronemus]

Brass will flow in strange ways when you make a big dimensional change. I think the neck diameter is much too small after sizing. I'm guessing that you've removed the expander from the sizing die; I'd recommend either using the expander or a mandrel to produce a more usual neck diameter.

 

[boltfluter]

Brass will flow in strange ways when you make a big dimensional change. I think the neck diameter is much too small after sizing. I'm guessing that you've removed the expander from the sizing die; I'd recommend either using the expander or a mandrel to produce a more usual neck diameter.

This. Way to much neck tension, on some cases, will make the shoulders collapse. Do something to get .002 to .003 neck tension and you should be on your way. Good luck.
Paul

 

[searcher]

I also think the expander ball/mandrel improperly positioned is your culprit. By removing it entirely, the neck isn't opened back up to a "finished" dimension, thus creating far too much neck tension. I have had this same thing happen when using too small of a sizing bushing. A tell-tale sign is the noticeable "bulge" in the neck where the area of the neck holding the seated bullet is visually much larger than the rest of the neck. That your virgin brass seated fine, it does point to your die setup.

 

[rocketron]

Your pic appears to show a lot of shaved jacket.

 

[John Beauchamp]

What's in the 550 ahead of the seating die. try setting the die up on the single stage and see if you still have a problem, just to narrow down the possibilities

 

[243winxb]

Stop crimping?
Why does the bullet look like it has* 2 different diameters?


The RCBS die is made to work with 223 brass/thin walls. This may be why it oversizes the necks when using Starline?
https://www.shootingillustrated.com/content/review-wilson-combat-300-ham-r/

 

[Coyotefurharvester]

You answered it yourself, .306 ID neck seated correctly, dry lube inside the neck helps with new/clean brass. Use a mandrel or the expander.

 

[DShortt]

For further confirmation, pull a bullet you've already seated and compare it to a new bullet. I'm betting you'll see the bullet has been swaged down by the case neck. As mentioned in post #8, if this case had more of a shoulder, it likely would have collapsed.

 

[RED DIRT]

So I'm loading 300 ham'r, which is basically a 30 caliber AR15 ... Bill Wilsons creation.

I'm sizing the case on an RCBS rock chucker with an RCBS die.

But i'm charging And seating the bullet on a Dillon 550C. Trying to mass produce.

Of course, the bullet diameter is 0.308. The sizing die gives an inside neck of 0.298.

But then when I try to seat the bullet, The neck tension goes to 0 and I can physically spin the bullet in the case.

  From the picture it looks like the
Case neck is flaring out and mushrooming.

I have tried threading the die in and out and moving the seating SStemin and out but nothing seems to fix the problem. I don't think the die is crunshing the case... But something is causing the Case neck to expand to 0 neck tension.

is the neck inside being 0.298 vs. the bullet being 0.308 Putting too much Pressure on the neck when seating the bullet?


Any ideas ?

Mic the bullets, make sure they`re correct diameter.
A set of Hornady dies will fix your problem. Not the first time i`ve seen this myself using RCBS dies as of lately.

 

[dellet]

A couple things.

First from the photo it looks like a boat tail bullet not seated past the boat tail. Not deep enough.
It thats not the case then check neck diameter before and after dropping the powder. You may have the powder funnel either adjusted wrong and flaring the case, or the wrong funnel, too large of diameter.

 

[GetReal]

Stop crimping?
Why does the bullet look like it has* 2 different diameters?


The RCBS die is made to work with 223 brass/thin walls. This may be why it oversizes the necks when using Starline?
https://www.shootingillustrated.com/content/review-wilson-combat-300-ham-r/
View attachment 1651792View attachment 1651818

Thats the bullet design, not shavings.

 

[GetReal]

Neck wall thickness is 0.018.... 0.314 o/s, 0.296 i/s. Bullet diameter is 0.307 - 0.308.

I think seating a 0.308 bullet into a 0.296 case neck is causing the neck to crush and mushroom out, as the pic shows..

 

[GetReal]

A couple things.

First from the photo it looks like a boat tail bullet not seated past the boat tail. Not deep enough.
It thats not the case then check neck diameter before and after dropping the powder. You may have the powder funnel either adjusted wrong and flaring the case, or the wrong funnel, too large of diameter.

Case neck is 0.296 before and after powder drop.

 

[DShortt]

Case neck is 0.296 before and after powder drop.

OK, well again, .011" to .012" of difference in bullet diameter and inside neck diameter is WAY too much difference. That's even worse than what you first reported. You can't cram a .308" bullet in a .296" hole without having problems like you are seeing.