Too much runout......

[waco]

Forming 257 Roberts brass from 30-06 is it possible somewhere in the process to make the necks off center? Maybe that's not the right term I'm looking for.
I loaded up some rounds and rolled them across the table and the bullet runout is VERY visible.

I can see it in empty brass as well as loaded rounds. Just not sure what to do. Nosler 257 brass is SPENDY!

I didn't notice this the first time I loaded the brass. Groups were horrible. 4-5" @ 100

Full length sizing the brass does not seem to fix the problem. Has anyone else run into anything like this before?

If so, what was the fix, if any???

Walter

[waco]

Is it possible my dies are causing the problem? I bought them new. Lee 3 die set. I have no other brass to judge by....

[country gent]

Check the wall thickness of the brass. if its not concentric it may be forming into a bannanna shaped cartridge. ALso are you forming in one step from 30 cal-25 cal ? Brass thats off to start with is a real issue at times. Lube cases with a good sizing lube. check and make sure case mouths are square and true. case thickness for even thickness. I suspect your ending up with original shoulder for case neck when reformed. A die that pushed the shoulder back at the gradual angle of the 06 to where it needs to be for 257 roberts then form down to 270 cal and full length at 25 cal and set sholulder to needed dimension. You might try fire forming with out a bullet. 8-12 grns of uniuque and a wad fire with rifle upright. This should pressure form cases to true form. Also How do cases fired from this rifle look? ANd measure out. Measure cases for oval out of round also. Going from 30 cal to 25 cal in one pass can be done it may be the shoulder pushing back thats causing the problem. Also have you annealed the necks shoulder area? That may help the brass to form being softer.

[EDG]

You might need repeat the entire case forming process with a few cases to see where the error occurs.

Try forming in steps and rotating the case between each step. Then roll the cases on a smooth flat surface to see if the necks wobble.

After getting to the final shoulder position rotate the case and size it 3 or 4 times rotating the case about 90 to 120 degrees per sizing stroke with a 7mm trim die. Then FL size and rotate. It may take a bit more work but the rotation will prevent the case from being formed out of square.

Finally seat a few bullets and roll the seated bullets across a flat smooth surface. You will be able to see .003 runout with a little practice.

I formed 25-06 brass from 30-06 GI Match brass long ago. It shot pretty poor for a 700 Rem.- about 1.5" to 2.0" groups.
One day I rolled the ammo and found that the bullet tips wobbled up and down a lot. I took the dies to work and chucked them in a lathe and found the
seating die had a lot of runout. I called the die company and they said send it back with both dies, sample bullets and samples brass. About 10 days later I got my stuff back but the dies were a new set. And the rifle went to shooting 5/8" groups like the rest of my 700 Remingtons.

If you cannot figure it out I have some brass you can play with and I have FL, Form and trim dies for both 7X57 and .257 Roberts that I can test for you.
Here are some of the neck sizes. Notice how large the CH form die is . Some steps are not very large so I may jump down 2 steps




















7x57-.257-6mm










family necks
Deltas 1 step
Deltas 2 Step


7X57
CH Form
.323






7X57
RCBS Trim
.315
.008




7X57
RCBS FL
.306
.009
.0170


7X57
Forster FL
.304
.002
.0090


7X57
Herters FL
.299
.005
.0070


.2570
Pacific Trim
.291
.008
.0130


.2570
RCBS Trim
.287
.004
.0120


.2570
RCBS FL
.278
.009
.0130


6mm
RCBSTrim
.277
.001
.0100


6mm
RCBS FL
.266
.011
.0120

[waco]

Thanks for the replys. I didn't form the brass myself. It was purchased.

[waco]

160500

[waco]

sorry about the pic being sideways

[EDG]

wow - bananas lol

Try rolling the crooked ones on a smooth flat table top. You will be amazed at how much those will flop around.

You need to pull a few down and resize in good die
rotate them and size about 3 times but only pull the expander back out on the last pass.
See if that helps.

A trim die would permit you to resize without pulling them down.

I don't know how that happened but something really went wrong.

[GONRA]

GONRA wonders if axial alignment / centerlne of the press is all messed up?

[country gent]

My coax loads very concentric ammo but give it cases that arnt concentric in thickness and all goes out the window as to run out. .002-.003 can make a big diffrence in how evenly the cases size. Another place to check is case heads squareness.

[MT Chambers]

My coax loads very concentric ammo but give it cases that arnt concentric in thickness and all goes out the window as to run out. .002-.003 can make a big diffrence in how evenly the cases size. Another place to check is case heads squareness.
I believe that if you use proper dies, and a Coax to size the cases initially, you should have good, concentric rounds.