"Houston, we have a problem"

[bwaites]

I want all the pictures!!

Its a teaching process for all of us!

[Hoot]

I want all the pictures!!

Its a teaching process for all of us!

Here's an excerpt from a more lengthy post paralleling this one over on beyond556.com:

...snip...

In the next image, you can see the narrowing imparted to the new brass after sizing them:



Back home, I tumbled all the brass, inspected them for any damage and burnished the powder residue out of the insides of the necks. I set one aside as a reference and ran the remaining 47 through the resizing/decapping process again using the same setup and procedure as earlier.

When I went to load my next experiments, that is when I ran into the problem already explained. Close examination of the reference cases revealed what may be the problem.

In the next image, you can see a new case alongside a fired, unsized case. The ring did not "iron out" from shooting.



Sizing the fired cases again exacerbated the ring to the point where when I went to seat my next experiments they seized when the bearing surface of the bullet reached that ring. I doubt fire forming those damaged cases will bring them back to normal, So I'm writing them off as a costly lesson.

The next batch will be initially sized by adjusting the sizing die down to where it just touches the shoulder and locking it down there as opposed to where it firmly engages the shell holder, a turn further down from that point.

Thanks to everyone who responded. Hopefully, you will not hear of this problem reoccurring as I learn the do's and dont's of reloading this caliber.

One person asked what the resulting OD neck size was if I just sized without the decapper. That figure is .2855, which I personally feel is a bit much for a .300 neck chamber, but that's what I got with the Hornady die. I am ever so slowly lapping the neck portion of the die open to more like what the new brass come in at. That being .2883. Doing so may make it easier for the expander to create an ID closer to .262. I am going slow, having spent the entire evening getting it up to .2863 when I quit for bedtime, which is now past. 04:30 comes pretty early. More tomorrow evening...

Hoot

[bwaites]

So if I understand you, you believe that there is an inside ring, a doughnut, formed by resizing?

This happens with resizing brass when you neck down, say when people resize 7.62x39 to Grendel, but I've not heard of it happening with Grendel brass.

People solve this by inside neck reaming the brass.

[Hoot]

Bill, this defies my core understanding of metallurgy. It appears not to be a dougnut example A.
It looks like buckling example B.




Makes no sense to me at all. Bear in mind it is extremely subtle. IE I can't feel it on the inside with a dental pick. I've checked and re-checked and it is not a manufacturing mistake on the inside of the die. The die transitions from the shoulder to the neck perfectly.

Hoot

[Rapidrob]

Thank you for all you photo's and measurements. you nailed it. Your sizing die is the culprit. Just because dies are new and expensive, that does not make them perfect. Many times over the years I've had to send dies back. The reamer used to cut the die was: Too worn,too small,chattered,off center,etc.
your on the right track with honing out the neck. My general rule of thumb is to never move the shoulder back once it has been fired out of my rifle. My dies are made to small base size and neck size only. It seems to work well in my semi-auto rifles.

[pinzgauer]

I've seen something like this happen with 7/08 RP brass with a collet die when I had it set too low. In my case the bulge was outwards where the shoulder met the main case wall. I had to full length resize the once fired to get it right. And in some cases, pull the bullets and resize as they would not chamber.

By the way, I'd have expected the expander ball to correct your problem on the upstroke. It also appears that the overall case length is shorter by the buckle amount... is that just the photo or is there a difference?

Lastly, do you really want to lap the neck section of the die??? Unless you are concerned it's overworking the brass I'd focus on the expander ball. Even at it's current smaller dimension the ball should expand it to it's size (expander ball OD + wall thickness minus spring back). The Hornady dies have a setup point for where they want the ball to be. If you do not do that you can run into problems. From memory it's where the air vent bleed hole is.

[Hoot]

My new box of brass comes in like the last box (different lot#) with .257 ID / .289 OD necks. There is no point in having a sizing die that sizes the OD even further down (.285) as was the case with mine. That's why I've been painfully, slowly lapping it a little more open. After two nights effort, mine is now up to where it resizes (.299) fired case necks down to .288. The .2628 expander then opens them enough to slip through and they snap back to .2615. The same as when my necks were sized down to .285. One more evening's effort should get the die to where it resizes the .299 necks down to .289, just like virgin brass. I'm really trying to reduce work hardening with that effort as it seems to have no effect upon the final ID once the expander drags back out, but I believe it will improve the life expectancy of the brass. At that point, I will stop, do an initial loading, shoot it and process the spent brass to see if they still prefer to collapse, rather than seat the bullets. If I still get collapsing, I will try to get another expander plug from Hornady. If I get time today, I will call Hornady and see if I can find out what the spec is supposed to be on that tapered decapping/expanding plug. The die parallels my chamber dimensions fairly well excluding the neck OD. Here's a graphical representation of the dimensions. The trained eye will see that the particular piece of unsized brass I chose to measure was from a particularly hot load (30gr 8208/Nosler 100gr BT/2821fps). My first loadings had more neck tension than was probably good for them.



Hoot

Edit: I forgot to answer your question. The ball was set to where the stem managed to push out the primer and fully pass through the neck into the case body before the neck is sized further up. I did not note where that fell WRT the bleed hole.