Thicker neck walls: Any down side?

[Brians356]

I am contemplating forming 6mm Rem from 7x57 Mauser brass. Based on preliminary tests, I expect neck walls to thicken to ~.0165 - .0170". They will require turning before I can use them in my standard 6mm Rem chamber w/ a .276" neck. I believe if I turn them to .015", the loaded rounds will clear the chamber by .003".

Case neck walls at .015" are thicker than I have experienced. Assume (please!) no doughnut issues or neck clearance issues, a question:

Are there any issues related to necks that thick? (I ask because some folks say they prefer to turn necks down to .012" for example.)

 

[Dusty Stevens]

Youll just have to measure over a seated bullet to see what youll end up with on your brass and bullet. I form mine from 30-06 cause i still find it tuff for 7x57 sightings

 

[Brians356]

Youll just have to measure over a seated bullet to see what youll end up with on your brass and bullet.

Sure, I know that part, TBD. I was asking about the implications of thicker vs thinner neck walls (in general.)

I form mine from 30-06 cause i still find it tuff for 7x57 sightings

You mean 7x57 brass hard to find? Yeah, I just got some from a friend, not always available. But Norma makes some exquisite (if expensive) 7x57 I hear, and the Prvi Partizan is available today for $0.58 the copy.

 

[ShootDots]

It has been my experience that no matter the cartridge, if you have necks walls in the 15 thousandths area you REALLY have to anneal every time and you still get a lot of variations in the "force" it takes to seat the bullet. They rarely seem to go in the same or smoothly. However, I have found that no matter what cartridge I use, I turn the necks walls down to 12 thousandths thickness. This allows every cartridge to seat bullets very consistently and smooth as butter. Now I realize that most of the time that takes a reamer with a neck to make 3-4 thousandths clearance, without "excessive" neck clearance. I use quotation marks for excessive because I had one reamer that gave me 7 thousandths clearance, with 12 thousandths neck wall thickness, in one of my cartridges with no ill effects.

 

[fguffey]

brians356, I have a 7mm57 reamer, if I ream a chamber to 7mm57 I have to be concerned with the outside neck diameter of a loaded round. If I am forming 7mm57 cases for a military type rifle chambered to 7mm57 a thick case neck is not a big concern. I have a few friends that chambered their 7mm57 to 280 Remington, problem, the 280 Remington reamer will not clean up the 7mm57 chamber. When fired the case neck has two neck diameters, part of the neck is the old neck of the 7mm57 chamber..

No different when the 308 W chamber is chambered to 30/06. The 30/06 reamer will not clean up the 308 W chamber.

F. Guffey

 

[Brians356]

brians356, I have a 7mm57 reamer, if I ream a chamber to 7mm57 I have to be concerned with the outside neck diameter of a loaded round. If I am forming 7mm57 cases for a military type rifle chambered to 7mm57 a thick case neck is not a big concern. I have a few friends that chambered their 7mm57 to 280 Remington, problem, the 280 Remington reamer will not clean up the 7mm57 chamber. When fired the case neck has two neck diameters, part of the neck is the old neck of the 7mm57 chamber..

No different when the 308 W chamber is chambered to 30/06. The 30/06 reamer will not clean up the 308 W chamber.

Thanks. Interesting info. Not related to my question (forming 7x57 to 6mm Rem) but interesting nonetheless.

 

[ShootDots]

Brian, there is another benefit to forming 7 x 57 brass to 6mm Rem. Quite awhile ago I had a 6mm Rem A.I. I used for deer hunting. I read an article by Jon R. Sundra about his experiences with the 6mm Rem. He said that if you neck down 7 x 57 Norma brass to 6mm you will gain an additional 1 grain of powder. That statement by him proved to be true. Not only is Norma brass MUCH better than run of the mill Remington brass, you get a little larger boiler room. Not much of a gain, but it is a benefit for free!

 

[mikecr]

Load development and tension tweaking with it should work like any other thickness.
As far as constant annealing; not needed unless excess clearance & sizing.

 

[fguffey]

Thanks. Interesting info. Not related to my question (forming 7x57 to 6mm Rem) but interesting nonetheless.

I start with a 30/06 then form to 7mm57, then I neck size to 257 Roberts, or 6mm Remington. When forming 30/06 to 6mm Remington do-nuts form in the neck at the shoulder/neck juncture (on the inside). I have a 6mm/243 reamer die that makes the job easier.

F. Guffey

 

[Brians356]

Brian, there is another benefit to forming 7 x 57 brass to 6mm Rem. Quite awhile ago I had a 6mm Rem A.I. I used for deer hunting. I read an article by Jon R. Sundra about his experiences with the 6mm Rem. He said that if you neck down 7 x 57 Norma brass to 6mm you will gain an additional 1 grain of powder. That statement by him proved to be true. Not only is Norma brass MUCH better than run of the mill Remington brass, you get a little larger boiler room. Not much of a gain, but it is a benefit for free!

I guess Norma must be a little thinner walled in the boiler. Good to know.

Someone gave me three Federal 7x57 cases some time ago, to experiment on. The three cases' neck thicknesses vary half a thousandth on average (.0004, .0005 and .0006) which is the best production brass I've personally ever measured, including Lapua and Nosler. I wish I had a bunch more of that lot.

How does the Norma neck variability stack up?

Another interesting thing I noticed was during sizing 257 Roberts down to 6mm Rem. The neck variation in the R.P Roberts brass was .0010" (pretty darn good for R.P!) but after sizing it down to 6mm the variation dropped to only .0006".

 

[fguffey]

Another interesting thing I noticed was during sizing 257 Roberts down to 6mm Rem. The neck variation in the R.P Roberts brass was .0010" (pretty darn good for R.P!) but after sizing it down to 6mm the variation dropped to only .0006".

It is assumed the neck gets thicker and or thinner when necking up or down, for those that measure before and again after they find the neck gets longer and or shorter.

F. Guffey

 

[Brians356]

It is assumed the neck gets thicker and or thinner when necking up or down,

I referred to reduction in variation, not change in thickness which will of course increase when necking down.

 

[fguffey]

I referred to reduction in variation, not change in thickness which will of course increase when necking down.

When I form wildcats I neck the cases up. When I neck up cases the case gets shorter, I have cases I have formed that shortened .035" in the forming process. The same case shortened another .010" when fired for a total of .045". when forming the case did not shorten between the shoulder and case head.

F. Guffey

 

[Brians356]

I had wondered whatever happened to the "Energizer Bunny". Not no more.

 

[fguffey]

I had wondered whatever happened to the "Energizer Bunny". Not no more.

The neck gets thicker and or thinner? The neck gets longer or shorter? Or is it both?

I said I have a reamer die for 6MM, when I go from 30/06 to 243 the donut at the shoulder/neck juncture almost closes the neck off. That has nothing to do with the 30/06 neck, I am forming the neck of the 6mm from the 30/06 case body.

F. Guffey

 

[Dusty Stevens]

I had wondered whatever happened to the "Energizer Bunny". Not no more.

Its left field all day and keeps goin and goin...

 

[fguffey]

Its left field all day and keeps goin and goin...

Its left field all day?

I am contemplating forming 6mm Rem from 7x57 Mauser brass. Based on preliminary tests,

Necking up and or down is not forming. Again, I use 30/06 cases to form 7mm57 cases. When case forming the reloader can off set the length of the chamber with the length of the case.

F. Guffey

 

[Brians356]

I am contemplating forming 6mm Rem from 7x57 Mauser brass. Based on preliminary tests,

Necking up and or down is not forming.

Strictly speaking (taking my cue from you) making 6mm Rem from 7x57mm Mauser is "forming", in that a) the shoulder angle is changed (steepened) and b) the body length is shortened. But otherwise, nothing is changed.

No need to respond, really, for we are like "ships that pass in the night."

Again, I use 30/06 cases to form 7mm57 cases. When case forming the reloader can off set the length of the chamber with the length of the case.

Again, interesting, but again, not really interested. "For now we see through a glass, darkly."

Edit:

PS Try something, for me, fguffy. Take any 7x57mm case and simply neck it down to 6mm. Don't touch the body or shoulder - use a 7x57 bushing neck die, for example, and a .272" bushing. Then try to chamber that case in a 6mm Rem chamber. Let me know how that works out!