Two different neck sizes on .222?

[mefizto]

Greetings all,

you might have noticed my obsession trying to figure out the cases and chambers dimensions. ;-)

As part of the obsession, I have measured several .222 cases that I have been hording, because one of those days, someone offers a rifle built on an action that accept two-stage trigger, and I will obtain it.

The cases fall into two distinct categories, one with neck size 0.254 inch and the other with neck size 0.246 inches. I have consulted SAAMI. but the only reference is for 0.254 inches neck size.

Any input?

Kindest regards,

M

 

[AccelR8]

There's been all kinds of 222 chambers cut with non standard necks in attempts to achieve improved accuracy. I am aware of chambers that have been cut with SAAMI standard .254" as well as non standard .250" and .246" and it seems to me I've heard of even smaller, like .244" IIRC.

SAAMI specs ensure standard, off the shelf factory ammo will fit into all rifles built to the SAAMI specification of .254. The other "accuracy"chambers with smaller necks will need brass with necks turned to fit the chamber with possible exceptions like the .250 neck.

All of the factory 222 ammo I have measures right around .248" which means with a SAAMI neck you'd have what, .006" between the cartridge and chamber necks. Some people belive accuracy can be improved by reducing that clearance to as little as .002.

If you buy a factory rifle you can almost be certain it will have a .254" neck. If it's a custom, it most likely will be .254 but could well be one of the others.

At least this is what I know, there are others here with much more experience than I. I know with my .246 neck chamber, factory ammo is a no go. Will not chamber. At this point I kinda wish I had chosen a .254" chamber.

 

[jds holler]

A .246 chamber neck would be a royal pain in the butt if ya ask me. I love the nice thick, long neck on the 222. It's durable and allows for a lot of latitude in bullet type.

I've got a .246 neck in my 22BR, and have had enough of it. I'm ready to find out what's involved in opening it up to standard neck and quit messing with neck turning. jd