When do necks

[Bob3700]

No matter how u establish ur neck thickness ( outside neck turning or inside neck reaming) , how many firings does it take to stabilize the neck thickness? Seems that brass is always flowing forward, even with sharper shoulder angles.
Those who outside neck turn, how many firings before u re-turn the necks to maintain ur neck thickness?

If ur using a mandrel to establish neck tension, seems that u are just pushing the extra brass flowing into the neck to the outside. The mandrel will help u identify when donuts are starting to form, u will feel them in the bass of the neck. Eventually, u have to re-turn ur necks to keep a consistent thickness.

Thoughts!

 

[C.E.Smith043]

I would say a minimal neck clearance would help. ie. tight neck chamber

 

[Bill Norris]

No matter how u establish ur neck thickness ( outside neck turning or inside neck reaming) , how many firings does it take to stabilize the neck thickness? Seems that brass is always flowing forward, even with sharper shoulder angles.
Those who outside neck turn, how many firings before u re-turn the necks to maintain ur neck thickness?

If ur using a mandrel to establish neck tension, seems that u are just pushing the extra brass flowing into the neck to the outside. The mandrel will help u identify when donuts are starting to form, u will feel them in the bass of the neck. Eventually, u have to re-turn ur necks to keep a consistent thickness.

Thoughts!

Normally on tight neck chamber brass I watch the loaded neck diameter and as it begins to thicken I will do a clean-up turn to maintain the clearance.

 

[Straightshooter1]

No matter how u establish ur neck thickness ( outside neck turning or inside neck reaming) , how many firings does it take to stabilize the neck thickness? Seems that brass is always flowing forward, even with sharper shoulder angles.
Those who outside neck turn, how many firings before u re-turn the necks to maintain ur neck thickness?

If ur using a mandrel to establish neck tension, seems that u are just pushing the extra brass flowing into the neck to the outside. The mandrel will help u identify when donuts are starting to form, u will feel them in the bass of the neck. Eventually, u have to re-turn ur necks to keep a consistent thickness.

Thoughts!

For my 6.5 PRC I've got 16 firings so far on my Lapua brass that was originally turned to .014" thickness after the 2nd firing. The neck still measures .014", but has a donut at the base of the neck.

Upon measuring one of those fired brass with a .265 pin gauge, it just fits into the neck to the donut and stops there. A .262 pin will still not go through the donut but a .261 pin will loosely go through. On FL sizing this brass and expanding the neck with a mandrel, a .263 pin will not quite fit into the neck, but a .262 pin will slide in all the way through without any hindrance from the donut. Measuring down the outside of the neck the diameter is larger on the neck just above the shoulder. From the neck-shoulder junction upward the thickness of the donut tapers off for a distance of ~.068 and from there towards the case mouth the neck thickness remains constant (@.014").

I've thought about turning the necks to get rid of that donut, but haven't since it hasn't been an issue for me loading my projectiles long where the bearing surface just doesn't touch the donut area. And the donuts are on the outside since I expand my necks with a mandrel. I guess, since I don't have a tight chamber, those donuts on the outside are just not an issue for me.

 

[jackieschmidt]

I disagree with the premis that necks keep getting thicker as they are fired.

I turn my 30 BR necks to .0098. It of course starts out as a Lapua 6BR case. I have cases that have as many as 20 firings on them, and the wall thickness where the bullet resides has not changed.
I am using what is commonly called a full length bushing die for sizing.

The same same can be said for my 6PPC.

I could care less what the thickness measures down at the shoulder neck junction. The base of the bullet never gets anywhere near that.

Which brings up a good point. In today’s world of accuracy, a shooter who is expecting optimum accuracy from a given set up should have his barrels chambered with a reamer that has a Freebore designed to work with the bullet he is shooting. This keeps the shank of the bullet from encountering any “donut” that will form, (despite all of your efforts) at the neck shoulder junction.

Extreme accuracy and optimum performance is not about compromises.

 

[Chris Edmondson]

The batch of Lapua 6.5 Creedmoor brass I'm shooting has been loaded 10 times including the first time. They were virgin turned inside and outside to 12.5 thou average, +/- 0.0002, they still mic to the average and tolerance. Despite turning a bit into the shoulder, I expect donuts to start showing up around 14x or so, I'll cull and shoot the rest a couple more times, then retire them to the recycle bin.

 

[Dave M.]

No matter how u establish ur neck thickness ( outside neck turning or inside neck reaming) , how many firings does it take to stabilize the neck thickness? Seems that brass is always flowing forward, even with sharper shoulder angles.
Those who outside neck turn, how many firings before u re-turn the necks to maintain ur neck thickness?

If ur using a mandrel to establish neck tension, seems that u are just pushing the extra brass flowing into the neck to the outside. The mandrel will help u identify when donuts are starting to form, u will feel them in the bass of the neck. Eventually, u have to re-turn ur necks to keep a consistent thickness.

Thoughts!

3

 

[paulT]

A lot can depend on the caliber plus if loaded rounds are pushed hard with higher velocities which can increase brass flow forward to case necks at a faster rate than running lower pressure/velocity nodes
I re turn my .308 palma brass on 3rd firing just a little clean up removing high spots on the necks
Sometimes i come across a case that needs an increased amount of material removed due to increased brass flow with that individual case which could end up causing a wtf issue during a match if not found and cleaned up.

 

[Bill Norris]

A lot can depend on the caliber plus if loaded rounds are pushed hard with higher velocities which can increase brass flow forward to case necks at a faster rate than running lower pressure/velocity nodes
I re turn my .308 palma brass on 3rd firing just a little clean up removing high spots on the necks
Sometimes i come across a case that needs an increased amount of material removed due to increased brass flow with that individual case which could end up causing a wtf issue during a match if not found and cleaned up.

Yea, I have seen it with my rifles too. It may be very slight growth but over time it does occur with some calibers. The likes of Jack Neary has spoken about seeing it happen with his B R 6PPC as well.

 

[Bob3700]

3

Paul n Jackie,
I shoot 308, 6 XC, 243 SLR, 6 BRX, n 6.5x284. I have made Fl sizing dies that provide for inline, inside neck reamingr. These are like the old Huntington (RCBS) inside reaming dies.
After Two firings, I can run the inside neck reamer down the case and I will always get some brass shavings. It is usually a small amount but it Is there. U can check the necks with a mandrel and tell when the necks are getting thicker. The mandrel drag on the inside case neck increases with each firing.
Inside neck ream the case and all goes back to normal.
All the above said, I run light neck tension ( inside neck reamer is .0005” under bullet diameter) and seat bullets long into the rifling. Let the bolt seat the bullet.
Annealing after each firing has significantly help generate consistent shoulder set backs.
This technique is not for benchrest shooting, but works well for prone/ sling to 1K for me.
Bob

 

[BartsBullets]

No matter how u establish ur neck thickness ( outside neck turning or inside neck reaming) , how many firings does it take to stabilize the neck thickness? Seems that brass is always flowing forward, even with sharper shoulder angles.
Those who outside neck turn, how many firings before u re-turn the necks to maintain ur neck thickness?

If ur using a mandrel to establish neck tension, seems that u are just pushing the extra brass flowing into the neck to the outside. The mandrel will help u identify when donuts are starting to form, u will feel them in the bass of the neck. Eventually, u have to re-turn ur necks to keep a consistent thickness.

Thoughts!

You are exactly Right!

Bart

 

[Richard Jones]

Extreme accuracy and optimum performance is not about compromises.

Well said, sir. A big nugget that we should all keep in mind.

 

[JEFFPPC]

My necks get thicker with firings. Jackie opinion aside, which I value, I have a cutter set up for the final cut that never gets moved. After maybe 8 to 10 firings I run all my cases back through it. 85% percent or more leave shavings. Go - no go, hard to argue with.

 

[searcher]

I have always considered my necks "done" after inside expand and neck turning. I have brass with 20-30 firings on them and I have run my unadjusted cutter over them after ten firings to "see what is up". A little brass was always shaved off the closer I got to the shoulder junction, starting well before half-way down the neck. There were also high spots shaved I attribute to the neck blowing out prior imperfections on the inside. Not enough to make me want to make frequent re-turning a part of my brass maintenance regimen, though if I were still shooting matches, I think I would. The brass flow does seem to build up closer to the neck junction, but ahead of it enough to dismiss it all as being a result of a doughnut. Regardless of cause - it is there. I noticed no improvement in my shooting (or sd's) after the second turn. I'd be very interested in seeing how this plays out with cases that were both inside and outside turned.

 

[Joe Salty]

I always check the necks to make sure they aren't getting thicker! I find after about my third firing on my dasher I do have to turn them again. Just remember that adds to your neck tension if you don't return them to the same thickness.

Joe Salt

 

[Mulligan]

I always check the necks to make sure they aren't getting thicker! I find after about my third firing on my dasher I do have to turn them again. Just remember that adds to your neck tension if you don't return them to the same thickness.

Joe Salt

And the buggers never grow in a uniform fashion!!!!
CW

 

[jackieschmidt]

I must be the luckiest shooter on the planet.
I have 6PPC necks, (.269 neck chamber), that have been fired so many times that the primer pockets have “zero” fit. 30 BR cases, (.330 (neck chamber), that I have lost count on how many times they have been fired.
The neck wall thickness has not changed when measured with a proper ball micrometer.

I set my 6PPC up to have .002 loaded round clearance, and my 30BR .0025.

I use only neck bushings, no mandrels.