What neck diameter for 243 or 243AI chamber?

[dwneill]

I want the have a Rem. 700 rebarreled in 243 or 243AI and would like to know what neck diameter to use. I know my stock 243's fired case measures .276. A new round and a reloaded shell with a lee die measures .271. What neck diameters are available on reamers for the 243 and 243AI. I'm trying to decide if i want or need a tight neck and have to neck turn my cases. Thanks Don

 

[J. Valentine]

.278 is the neck size on a Clymer reamer .
If you are considering a custom neck diameter but not neck turning.
You need to decide on what brass you are going to use.
Then buy some and seat some projectiles.
Then measure the largest case neck and add .002.
It might turn out close to standard anyway.
I don't think many gunsmiths have tight neck reamers for AI chambers.
If you want to neck turn then you have to come under that largest case neck diameter by how much you want to thin the necks.
Say approx .266 that would be a cleanup of approx .005.
I would not go too thin on the necks in a AI chamber.

 

[chino69]

.243 AI neck dia.

I want the have a Rem. 700 rebarreled in 243 or 243AI and would like to know what neck diameter to use. I know my stock 243's fired case measures .276. A new round and a reloaded shell with a lee die measures .271. What neck diameters are available on reamers for the 243 and 243AI. I'm trying to decide if i want or need a tight neck and have to neck turn my cases. Thanks Don

Don,
I have a reamer for a .243 AI with a .270 neck dia. It allows me to turn Lapua brass to .268 nd with good results. Haven't had any problems, cases fit chamber nicely and 100 rds. of new brass will outlast most barrels.

Chino69

 

[Dave Tooley]

I've got reamers with .265", .268",.272"and .274" seems like I lean to thicker necks these days on tight neck chambers. If your going to order your own reamer I would recommend going more than .002" over a loaded round. .004" over wouldn't be all bad. If you don't you may find yourself having to neck turn anyway. For a rifle to shoot accurately the fired case must allow a bullet to be freely inserted into a fired case.

Dave