Question on neck turned brass

[JamesnTN]

I have my neck turner setup to turn my dasher cases to loaded round of .266 and the chamber is a .268 I carefully ensure my turner is set properly by the expense of trashing a few pieces of brass setting it up. Anyhow after I have it set it never gets re adjusted as I always use the same reamer, today as I wa seating bullets I noticed a few had less seating pressure over others so I got out the mids and started measuring my brass, I found the heavier seating pressure brass was .0005 smaller than my goal setting and then lighter seating pressure was .001 below my .266 loaded round case.

When I set up my turner I loaded up a few rounds to make 100% sure it was at .266 with a seated bullet. My question is has anyone ever experienced the neck brass flow go thinner? I'm not sure if I'm asking the question the right way but something has changed and I know it's not my neck turner because I turned another piece of brass and seated a bullet and it measured .266 so what's going on here?

 

[KMart]

I just recently noticed the same thing. After skim turning some new 6BR cases, I seated a couple of bullets and measured the loaded necks. My records shows they measured .267.

The cases have now been cycled through several times and annealed one time. The loaded neck is now just a little shy of .268.

I'm glad I'm not the only one.

 

[JamesnTN]

I just recently noticed the same thing. After skim turning some new 6BR cases, I seated a couple of bullets and measured the loaded necks. My records shows they measured .267.

The cases have now been cycled through several times and annealed one time. The loaded neck is now just a little shy of .268.

I'm glad I'm not the only one.

I've seen them grow but never shrink. Not unless my bullets are smaller dia than what I set my turner up for. I haven't checked that.

 

[KMart]

sorry James, I misread your post.

 

[Joe R]

JamesnTN

I have my neck turner setup to turn my dasher cases to loaded round of .266 and the chamber is a .268 I carefully ensure my turner is set properly by the expense of trashing a few pieces of brass setting it up. Anyhow after I have it set it never gets re adjusted as I always use the same reamer, today as I wa seating bullets I noticed a few had less seating pressure over others so I got out the mids and started measuring my brass, I found the heavier seating pressure brass was .0005 smaller than my goal setting and then lighter seating pressure was .001 below my .266 loaded round case.

When I set up my turner I loaded up a few rounds to make 100% sure it was at .266 with a seated bullet. My question is has anyone ever experienced the neck brass flow go thinner? I'm not sure if I'm asking the question the right way but something has changed and I know it's not my neck turner because I turned another piece of brass and seated a bullet and it measured .266 so what's going on here?

James,
I don't shoot a Dasher, so I'm going out on a limb here, but I've read in several places that .003 is the necessary minimum neck clearance to have a good bullet release. Could it be that the necks is too tight and to release the bullet the pressure is forcing the brass somewhere else (down the shoulder) ?

I would pm dmoran or shootdots, they both love their Dasher and can probably answer your question.

Kindest regards,

Joe

 

[Toby Bradshaw]

If the surface finish of your freshly-turned necks is not perfectly smooth, the pressure from firing will flatten out the micro-ridges, causing the neck to measure thinner. This happens within a few firings.

Necks can also thin over long periods of time and many reloadings if the outside of the neck is cleaned with an abrasive like steel wool.

 

[JamesnTN]

For time being after thinking all this thru I'm going out on the limb and say Berger Hybrids are a smaller dia over the VLD and 108 BT. Reason I'm thinking this now is the neck turner has never been re adjusted from the time it was setup so I know on all my other brass a loaded round measures .266. Now on my bushing die I had to use a .001 smaller bushing on the hybrids because the bushing I was using on all my other Dashers the bullet would slip in and out of the case. So that's for now is where I'm coming up with smaller dia bullets which makes my necks measure smaller on the loaded round.

 

[savagedasher]

I gave up on neck turning brass. I find .2704 no turn chamber works the best for me. I do a double step on the neck. My full length bump die has a reamed neck that my neck ends up being .269 . I change my die and do 50%of the neck for what ever neck size I want for seating,
The only way I had success was to use a real lathe with a guided stem larger then the id of the neck,
Larry

 

[ridgeway]

Few questions...

What are you using to measure with? You pretty much need a 1" micrometer and a 1" ball micrometer that reads down to a tenth to really see where you are at in order to troubleshoot.

Are you annealing after each firing?

 

[boltfluter]

Toby is right on the money. IMHO.

Regards, Paul

www.boltfluting.com

 

[tenring]

I have the same experience. I turn necks on 4 BR guns. I dedicate a K&M neck turner for each. I measure neck thickness with a Mitutoyo ball mic. No matter how tight I torque down the turner, after about 20 consecutive turns, I find the one side neck thickness has slipped down about one or two ten thous. I re-tighten the turner without changing the setting, and get the same result. I am not knocking the K&M cause I love them, but find this to be frustrating.

 

[OldmanFCSA]

I have the same experience. I turn necks on 4 BR guns. I dedicate a K&M neck turner for each. I measure neck thickness with a Mitutoyo ball mic. No matter how tight I torque down the turner, after about 20 consecutive turns, I find the one side neck thickness has slipped down about one or two ten thous. I re-tighten the turner without changing the setting, and get the same result. I am not knocking the K&M cause I love them, but find this to be frustrating.

This duplicates my experience and setups.
I've gone to annealing after every firing to keep my neck tension near the same as possible.
I triple re-size each case, rotating 120 between each re-size - works for me.
1. I knock out primers.
2. I tumble in SS Pins.
3. I anneal after every firing.
4. I resize as stated above.
5. I check for donuts and trim necks for diameter and length.
6. I polish burrs off with fine ScotchBrite.
7. I wash and dry cases.
8. I lubs case neck and projectile with graphite.
9. I seat paying careful attention to seating pressure.
10. Above is for Match ammo only.

YMMV.

 

[dkhunt14]

I use K&M turners but I set 3 turners up for turning. I like a new sharp cutter for last turn. I take the turns in 3 passes and can do hundreds of cases and it never changes. For the Dasher I turn the neck to about 1/16 from shoulder. When it forms my turn is half way down the shoulder. Matt