Modify a sizer die

[abunaitoo]

Friend has run into a tiny problem.
308 Win full length sizer. RCBS die I gave him.
He insist on full length sizing for his bolt rifle.
He measures the cases every time.
He noticed that the cases seem to grow .08 to .012 every time.
He does lube the neck inside and out.
So he has to trim them every time.
His load is in the upper part of the scale.
Now......I was thinking.........
When sizing a case, the neck is sized, in the die, smaller than .308.
Then the sizer ball is pulled through to resize it to, hopefully, the correct size.
If the die is sizing the neck to small, the force of the ball would pull the neck up while sizing.
Make sense?????
Now.....if I open up the die neck sizer, so that it is close to the ball sizer diameter, it would lessen the force of the ball pulling through the neck.
Thoughts, comments??????

[country gent]

That will help some with the ball force. Polishing the ball ( not removing a lot just making it smooth) can help here also. The die modification may cause problems with some thinner brass in not sizing down enough. The whole problem here may not be in the neck portion of the die, but in a combination of things. Measure some fired cases head mid point on body shoulder and some sized cases at the same points. I have seen this with a larger chamber and smaller die. The body expands on firing to fill the chambers larger size, then the sizing die squeezes this back down to minimum or close to it and all the "extra" flows forward. Check his cases for lines at the head inside the cases ( a bent paper clip with a sharp point will allow you to feel them. A bore scope allows you to see them)
I went to a redding full length bushing die and no expander for 308,243 and 223. This allows me to size just what I need for a batch of brass The bushing is a good way to go here, as it also allows to adjust for neck tension when desired.
Polish the expander ball to a mirror finish. this isn't to hard to do in a lath or drill press mount the decap rod and ball. A felt bob in the dremil tool. Impregnate the bob with green rouge run drill press at lowest rpm and with the dremil running full buff the ball to a mirror finish. The idea isn't to remove metal but to polish surface smooth so it dosnt grab or pull on the brass. If desired you can finish with a second bob and red rouge.

[1hole]

Comments:

Eight to twelve thou of stretch per firing is a LOT, two or three is about ideal for most of our needs. All that brass is being stretched out of the case web and your friend is working for a catastrophic head separation!

Neither expander drag nor chamber pressure, as such, contributes much to brass flowing into case necks. Stretching comes from to much shoulder set back and it's excessive "FL" sizing that does the deed. Repeatedly jamming every case as far into a sizer as it can possibly go is a mistake, don't/won't resize like that!

Hand loading offers us several options that factory ammo cannot. One of those options is to only FL size enough to set our own shoulders back so our loaded cases snugly fit our own chambers, not everyone else's. (It's easiest to control with a case base-to-shoulder length gage - Hornady or RCBS - which gives us that reading to a thousant.) And that's NOT so called "partial" FL sizing, it's precisely FL sizing for our own rifles, not for every rifle in that cartridge that's ever been made.

Individual case spring back varies enough that it's impossible to make each case exactly the same so I aim for 2-3 thou of sized shoulder set back for my hunting ammo and chambering is smooth and easy. I have many cases that have been fired about 20 times before needing trimming a second time. I've been FL sizing my ammo that way (with hot loads) for a dozen or more bottle necked rifles for more than 50 years and have never had a single failure to chamber nor signs of a coming head separation. With occasional careful neck annealing, my cases die from (safe) split necks, not explosive separations!

[HangFireW8]

Abunaitoo,

Your thinking is correct. Most case stretch comes from the sizer ball. And mostly because the neck is sized too small.

But the real problem here is a reloader that refuses to learn and try new things. Perhaps he was taught to always FL size hunting ammo? If so he has to accept his short case life and replace often. As with all of us, he should be checking for incipient case head seperation... but he should be doing it more often!

[abunaitoo]

He has a neck size die.
Also a Lee collet die I told him to get.
He still refuses to use them.
Have no idea why.
He just started reloading.
He has been getting good results.
Most of the tools he got from me.

[Walks]

Some people are only willing to do things a certain way.

I'm still sizing bottleneck cases the way my DAD taught me almost 60yrs ago. I prefer to fire specially Partial Sized brass rather then neck-sizing once fired brass.

I have in the past broken down factory ammo, expanded the case necks one caliber, and then neck-sized the case until it just fits into the chamber.
I then reassemble the factory components to create a perfectly fitting round.
No stretch, a case fitted to that rifle. It will never need to be trimmed more then that first time and should last 10 reloadings.

[CASTER OF LEAD]

Once my brass(new, or even new to me brass) is FL sized, trimmed if needed, and shot from MY gun it is dedicated to that gun and chamber. From there I use the Lee collet die only, Unless I start to encounter length issues.
At that point I FL size , but only size as stated above. Just enough to to set things back to where the need to be for that rifle. Then it's back to neck sizing only. My best advice is advise your friend to take heed, and try to adopt similar habits. Never had an explosive head separation nor do I ever want one. I have however seen some guns that have had it happen. Not pretty and could potentially be deadly. Just my 2cents. - Caster

[MostlyLeverGuns]

Full-length sizing EVERY time only works when the die is carefully set to size the minimum amount to allow a cartridge case to chamber easily. A 'long' chamber and 'short' cartridge case can move brass toward the neck every time it is fired. I use the Redding Competition shellholders that allow full-length resizing but adjusted to chamber length using the shellholder. These shellholder come in +.002,+.004,
+.006,+.008,and +.010, others can be ordered from Redding. In my Savage 99's I have 4 that use the +.006 and 1 that takes +.008. These cases chamber freely. Without such a shellholder, the full-length die should be adjusted to size just enough to allow cases to chamber without resistance. I have cases that have been fired 5 times with full loads that show NO signs of incipient case head separation nor have they lengthened significantly. Cases should be checked regularly with a bent and sharpened piece of wire inside the case, sliding the wire to catch a groove or line of thinning brass near the case head. Once you can feel that separation starting, cases should be discarded. If case will rechamber freely after firing there is little gained by full-length sizing. This simple test is something not often done, but can simplify many resizing issues. I run 'stretchy' rear-locking Marlins and Savage 99s, but by not oversizing I will get 7-10 full power loadings in 243 and 308. Modestly loading cases last longer with annealing of the necks to prevent cracking. If you look at SAAMI specs for cartridge and chamber, there really can be a lot of slop and still meet specs. Many experienced reloaders discard cases on a third trimming or after trimming .015 total after the first trim. Case separations can be at best annoying with separated cases stuck in the chamber to dangerous with escaping gas blowing back through the action.

[abunaitoo]

I have modified a .223 die.
For the AR
I found that I was having problems with some reloads not chambering.
Not many of them, but it's a pain when it does happen.
Found that, sometimes, when loading the condom bullet, it would push out the shoulder a tiny bit.
Just enough to keep it from chambering.
I opened up the neck of a sizer die so it would not touch the neck of the loaded case.
Now after seating the bullet, then crimp, they run it through this modified die.
No more chambering problems.

[jmorris]

He noticed that the cases seem to grow .08 to .012 every time.

If you size them more than you need to, for them to fit the chamber and fire them, they blow out. Then you over size them again and they are too long.

Keep doing this without checking wall thickness in this area and he will have case head separation at some point.



You don’t need to modify the die, just adjust it correctly.