Getting grooves in 308win brass necks

Terry Perkins

Terry Perkins

CGN frequent flyer
Rating - 100%
85   0   0
Location
Bruce County
I am getting grooves on the outside of my brass necks during neck sizing. After trimming the brass I check the feel of the outside of the neck for any burrs. If there is, I use 0000 steel wool to smooth it out. I am still getting grooves on the outside of the neck when I neck size. I am neck sizing from .340" down to .335". I have made sure the bushings (titanium) are clean. Anyone with a solution? Thanks in advance.

Terry P
 
Are you using an adjusted FL sizing die to just size the neck, a dedicated solid neck sizing die, or a Lee collet neck sizing die?

With solid dies (no moving parts inside) I've had this happen several times and every time it turned out I had scratched the inside of the die in the neck area. It seems to only happen when sizing military brass (LC or IVI) but not every time. I run 1000 grit emery paper on a dowel with a split in the end chucked into a cordless drill to polish it out. I only size clean brass and don't know why it's military brass that seems to do it. I've done this to some of my dies 2-3 times with no noticeable difference in neck tension; the expander ball has more to do with that and I haven't touched mine.

If you're using a Lee collet neck sizing die you could have burrs on the fingers that compress inside the die to size the neck down. That can be cleaned up with a needle file or emery paper on a dowel.
 
Terry Perkins said:
I am getting grooves on the outside of my brass necks during neck sizing. After trimming the brass I check the feel of the outside of the neck for any burrs. If there is, I use 0000 steel wool to smooth it out. I am still getting grooves on the outside of the neck when I neck size. I am neck sizing from .340" down to .335". I have made sure the bushings (titanium) are clean. Anyone with a solution? Thanks in advance.

Terry P
Click to expand...

Your bushing is rough and picking up brass from the cases, you then have brass rubbing on brass.

Polish the bushing and make sure it has a smooth rounded/tapered end and a smooth inner surface.

I had a Hornady 9mm die that was titanium plated and had to polish the rough plating before it sized without marking my cases.

This left a bad impression of titanium plated dies and bushings after never having a problem with carbide dies or steel bushings.
 
I have never seen case lube that causes scratches or grooves in a case neck, but I have seen excess lube dent the case shoulders.

But I have seen rough bushings and burs at the neck shoulder junction of a standard die put marks on the neck.

And when the bushing and die were polished the problem was solved. It seems time is money and less care is used in the manufacture of dies today.

Below is a closeup photo of a RCBS expander that needs polished to keep the expander from excessive pulling on the case neck.

5Rqdvuh.jpg
 
Mr. Perkins, bigedp51 has it nailed down. Not only does titanium pick up (gall) easily, regular steel can too. You most likely have a slight buildup of brass (doesn't take much at all) in your die & it is 'grabbing' at your case necks, creating the grooves you're seeing. This sometimes gets bad enough to refuse to let go of your case. Fine steel wool on a drill can fix this if you know what you're doing.

Just a side note: back when I was machining for a living, I can tell you that titanium is as fickle as a medicated ex-wife! Stuff galled like mad to tools if you didn't closely monitor coolant & cutting speeds:p

Rooster
 
You must log in or register to reply here.
Back
Top Bottom