Neck sizing: My brain is fried, Im retarded...the math doesnt math

Make this make sense boys:

I measure neck outer diameter at .344 of a loaded round, so I ordered a .342 bushing. Too loose, zero tension, OD measures .342 now.

I order a .338 bushing. Size the brass, OD is .338. Still too loose, but now there's a slight bit of neck tension, but with some effort I can spin them remove the bullet.

Finally step down to .335, $120 into nothing but bushings at this point. Run the brass up and now....wait for it....OD is .331!

I repeated this across 10 more pieces. Inner diameter, measured with the same calipers, is .335....so the product is right, but for some reason, the .335 bushing is sizing down an extra 4 thou....wth?!

Pushing a round in results in .341 OD.

Die set is RCBS Matchmaster

Brass is mixed Browning and Federal nickel plated.

I have resorted to sizing down to .331, then running an old bullet upside down and literally hammering it into the case. Ironically, results in a perfect .335 OD! Like my 300WSM wadcutter?

Nickel plated brass is a headache... throw it away and go get some good brass.

308win said:

Nickel plated brass is a headache... throw it away and go get some good brass.

Click to expand...

Once the nickel coating wears off, everything changes and when that happens or how to tell? It's pretty and that's about it.

Good advice

98cwitr said:

Make this make sense boys:

I measure neck outer diameter at .344 of a loaded round, so I ordered a .342 bushing. Too loose, zero tension, OD measures .342 now.

I order a .338 bushing. Size the brass, OD is .338. Still too loose, but now there's a slight bit of neck tension, but with some effort I can spin them remove the bullet.

Finally step down to .335, $120 into nothing but bushings at this point. Run the brass up and now....wait for it....OD is .331!

I repeated this across 10 more pieces. Inner diameter, measured with the same calipers, is .335....so the product is right, but for some reason, the .335 bushing is sizing down an extra 4 thou....wth?!

Pushing a round in results in .341 OD.

Die set is RCBS Matchmaster

Brass is mixed Browning and Federal nickel plated.

I have resorted to sizing down to .331, then running an old bullet upside down and literally hammering it into the case. Ironically, results in a perfect .335 OD! Like my 300WSM wadcutter? View attachment 758292

Click to expand...

What is the OD of a sized neck measured at the case mouth ? Does it match the bushing ID ?
If not then the brass is either way to soft to hold or the bushing is moving up and not sizing or the brass is just so stiff and resisting

Use good brass with uniform neck wall thickness.

98cwitr said:

Make this make sense boys:

I measure neck outer diameter at .344 of a loaded round, so I ordered a .342 bushing. Too loose, zero tension, OD measures .342 now.

I order a .338 bushing. Size the brass, OD is .338. Still too loose, but now there's a slight bit of neck tension, but with some effort I can spin them remove the bullet.

Finally step down to .335, $120 into nothing but bushings at this point. Run the brass up and now....wait for it....OD is .331!

I repeated this across 10 more pieces. Inner diameter, measured with the same calipers, is .335....so the product is right, but for some reason, the .335 bushing is sizing down an extra 4 thou....wth?!

Pushing a round in results in .341 OD.

Die set is RCBS Matchmaster

Brass is mixed Browning and Federal nickel plated.

I have resorted to sizing down to .331, then running an old bullet upside down and literally hammering it into the case. Ironically, results in a perfect .335 OD! Like my 300WSM wadcutter? View attachment 758292

Click to expand...

The initial measurement didn't account for spring back unless your desired neck tension's was .001"

I've gone to .003" across the board with hunting and target loads. .003" won't set back on 10 cycles and pushing against my bench to the point it wants to flex.

You're using two different brands of brass that probably have two different neck thicknesses before the nickel plating which throws another kink into it.

Toss the nickel and get a lot of brass or all the same head stamp at least. That's my suggestion to start.

Also, do you have calipers that are sensitive enough to measure OD on a loaded round?

308win said:

Nickel plated brass is a headache... throw it away and go get some good brass.

Click to expand...

But its so shiny

Just tested some actual brass I have, Winchester headstamps, got .333.

rockchalk06 said:

The initial measurement didn't account for spring back unless your desired neck tension's was .001"

I've gone to .003" across the board with hunting and target loads. .003" won't set back on 10 cycles and pushing against my bench to the point it wants to flex.

You're using two different brands of brass that probably have two different neck thicknesses before the nickel plating which throws another kink into it.

Toss the nickel and get a lot of brass or all the same head stamp at least. That's my suggestion to start.

Also, do you have calipers that are sensitive enough to measure OD on a loaded round?

Click to expand...

Yep, got 100 pieces of Peterson waiting on me with my reloading guy.

Calipers are pretty good quality Lyman that'll do down to 1 thou, and accuracy is +/- 1 thou, so Ive found

Bitteroot said:

What is the OD of a sized neck measured at the case mouth ? Does it match the bushing ID ?
If not then the brass is either way to soft to hold or the bushing is moving up and not sizing or the brass is just so stiff and resisting

Click to expand...

Ive got the bushing screwed down as the die will let it. There a very minute rattle, but I can literally see where the bushing is getting down to.

OD at case mouth is .331 once run through the .335 bushing, but with both the .338 and .342, its perfect, despite the fact the .335 measures perfectly in my calipers, just as the other two do. I dont think its the bushing, and Im setting the other two same as the .335, so I am gonna join the blame-the-brass bandwagon until I can test it with the virgin Peterson I have waiting on me.

98cwitr said:

Ive got the bushing screwed down as the die will let it. There a very minute rattle, but I can literally see where the bushing is getting down to.

OD at case mouth is .331 once run through the .335 bushing, but with both the .338 and .342, its perfect, despite the fact the .335 measures perfectly in my calipers, just as the other two do. I dont think its the bushing, and Im setting the other two same as the .335, so I am gonna join the blame-the-brass bandwagon until I can test it with the virgin Peterson I have waiting on

Click to expand...

Ok just checking some obvious stuff. I always measure after the sizing to ensure the bushing is doing the job.
Difference between a loaded round OD and sized Brass OD equal bullet hold. Etc.

Unless I'm missing something here, you are not supposed to measure a sized piece of brass, you are supposed to measure a case with a bullet seated, then subtract the .002"-.003" to obtain the correct bushing.

Otherwise, I've been doing all of my neck honing incorrectly all these years…

Cheers.

There is neck wall consistency's to consider, out of round conditions when measuring. I'm hoping your new brass will be consistent and eliminate these uncertainties in these 2 different nickel brass manufacturers. A ball mic is nice to have especially in the event you may turn necks for chamber clearance and/or even out the material thickness variation.

Need to know the ID and OD of case neck. If you have turned the neck to a set thickness of the neck. So either take the ball out to sized the case neck if using neck sizing die. Check ID. Use a mandrel to set ID of neck. 3 or so thousands under bullet OD. You'll need to watch for spring back.
You can setup a formal on excel to give you the answers. I have one that I have setup to do several different calibers. It tell the mandrel and bushing size. Otherwise you will end up with a box of bushing that doesn't do you any good. Just like me. I use bushing to reduce my neck to a different caliber, so more bushing are needed. On excel you can set up fornal bullet OD, - tension, plus + double neck thickness. Tells the bushing required.
It works like this Neck tension wanted. ,003", bullet OD XXX, Mandrel size needed. Bushing size required.
Formal example: bullet size (.xxx), neck tension wanted ?, say .-003 mandrel size or minus -.xxx". Bushing size: Neck thickness x 2+bullet equal bushing needed. If using bushing dies, no mandrel needed. Done by the bushing to set neck tension. Deletes one step in working the brass neck.
The only problem is if your brass neck isn't turned then that formal possible not work do to the different in brass thickness. So mandrel will be needed depending on how you treat your brass. Nickel brass not recommended. Looks petty to start with, but nickel flakes off after time. Plus if you are cutting neck for a set thickness. The nickel is removed anyway.
Hopefully this helps. Hope I didn't screw everybody up. I tried at one time to place the work sheet here, but it wouldn't except it. I guess to much for the system.

I measure neck thickness, multiply time 2, add bullet diameter. Then subtract .003 to get bushing size. Has never failed me. I use pin gauges to check neck id on sized and fired brass. Nickel plated brass sucks