223 measurement

[Link]

I was looking at the 223 page and it gives a measurement of .253
with the bullet seated at the neck. [neck diam.]

I measured one at the local gun shop and it was .2495 with lapua brass.

What's up with that? What do you guys get on yours?

thanks Link

 

[SNAFUBAR]

I just measured 3 randomly from the loads I finished tonight.....mine are all .2495 as well,Lapua twice fired brass loaded with 80g Bergers)

 

[fdshuster]

Link: The dimensions shown on the 223 page are all maximum ctg. dimensions that can be chambered in a SAAMI spec chamber. As an example, case length is shown as 1.7598', and we all 'round up' to 1.760'. Same for ctg O.A.L., shown as 2.2598'/ rounded up to 2.260'. Every commercial 22 c.f. chamber neck dia. I've ever measured is .256'/.257', so again, the .2532' would 'fit'. And, yes, my Lapua 223 loaded neck diameters are around .249'/.2495', the reason my spec'ed chambering reamers include a neck diameter of .253', a good dia. for a tight, no-turn neck. Loaded 223 with Winchester brass will have a neck dia. of approx. .246' for a really sloppy fit in a 'large' chamber. Good observations on your part: you are on top of it.

 

[Link]

MMmmmm Thanks guys.

The reason for asking is I want to order my neck dies with the bushing. Should I order 2 bushings?
1 at .247 for the Lapua that measures .2495
& 1 at .244 for the L.C. brass?

And as for the neck size in my new chamber maybe a .252 or .253?

this is a .223 A.I. I am having built for my Contender.

thanks again.

 

[fdshuster]

Link: Again, you are on top of it. Thats the combination I use: .247' for Lapua brass and .244' for Winchester, Lake City, and 'other'. I actually have several other sizes, a few thousandths smaller & larger, but seldom use them. I think the only way you would get a smaller chamber neck dia. than 'standard' is if it's specified when the chambering reamer is cut, otherwise it will be .256'/.257'. With the neck bushing die, and the proper sized bushing you will be able to control the minimum as sized diameter,, a standard die will radically oversize/squeeze-down) and the big advantage remains in not having to use the inside neck expander. But, with a saami spec chamber neck dia., the necks will still be expanded to the .256'/.257' diameter., so you will be 'working' the brass approx. .010'.: .257' to .247'. With a tight, no-turn neck dia. of .253'/ .252' the brass will be worked around .005'/.006'. And that's the main reason I specify a tight,no-turn neck on my chambering reamers.