casing wall thickness and expansion

[kal]

Simple question, does a thicker walled casing expand and retract better or worse than a thinner walled casing?

[markm]

Are we talking rifle cases? What caliber, etc?

I've never noticed any difference in any cases in rifle or pistol, but I don't know how you would be able to tell. :confused:

[kal]

Are we talking rifle cases? What caliber, etc?

I've never noticed any difference in any cases in rifle or pistol, but I don't know how you would be able to tell. :confused:

i was asking in general.

And i guess the only way to answer the question is to examine the material and how it behaves under stress.

[markm]

It's a complete non issue in my experience....

[JStor]

For firing and extraction it makes no difference as long as the chamber is in spec. The loaded cartridge with bullet seated will measure a bit more at the neck with thicker brass than with the thinner brass, but both will be sized to the chamber on firing.

The more important issue with thicker walled casings is the necks will end up with too much neck tension when run through a standard die, hence the popularity of bushing type dies.

Examples would be .223 Lapua brass versus Winchester...though I don't know anybody who would use the expensive Lapua brass in an AR15 as it's too easy to lose. I reserve Lapua for bolt guns. That is if you are referring to a rifle round.

Also the thicker walled brass may have less capacity and provide higher pressure when loaded with the same powder charge, but I use the same powder weight for Lapua, Winchester and Lake City without any signs of overpressure. Velocity is near identical.

[markm]

The more important issue with thicker walled casings is the necks will end up with too much neck tension when run through a standard die, hence the popularity of bushing type dies.

Huh? On a standard resizing die... the last thing the brass gets is the expander ball. The neck tension should be identical for everything.

Although NOT exactly the same thing... I tried chronoing different crimps on the .223 and could find no velocity differences for any kind of crimp that might impact neck tension.

[JStor]

A Lapua case with bullet seated measures .252 inch. A loaded Winchester case with bullet seated will measure .247 inch. When fired, both will expand to .255 inch for my chamber. If you squeeze that Lapua case down to the .245 inch that a regular resizing die will do...you have neck tension of .005 inch. That may be okay for some, but .003 should be enough for an AR15 with its robust feeding cycle. And best accuracy is usually attained with .001-.002 neck tension. Redding recommends resizing no more than .005 inch in one pass to maintain concentricity, thus all my brass first gets the .250 inch bushing. Of course, for blasting ammo, it probably doesn't matter, but I am shooting tiny groups with a varmint rifle, a Winchester Model 70 Heavy Varmint.

The brass that I weighed had Lapua at 97.33 grains and Winchester at 96.83 only a .5 grain difference. From that I figure the weight difference is in the neck thickness. It only makes sense for Lapua to be thicker as it is match brass, and some of the shooters want to neck turn the brass for total consistency. Pulling the expander ball back through the neck on my RCBS full length sizing die leaves brass at the mentioned .245 inch. I usually use Winchester brass, and use Redding Competition neck and body dies with a .250 bushing and then a .245 bushing for the varmint ammo on the Winchester brass. But Lapua brass is so great, I thought I'd give it a try as I use it in a .308 rifle.