To turn or not to turn ?

[rem 243]

Hey necking down 300 SAUM norma brass to 7mm SAUM, is it imperative to neck turn the brass ?
Will the necking down process cause the brass in the neck to become uneven ???
Does necking it down in two steps help reduce this ?

Cheers in advance Steff.

 

[dkhunt14]

When I necked 340 Weatherby brass down to make 308 Baer the brass got 1 thousandth thicker. If the wall was 15 it went to 16 and if it was 15 1/2 it went to 16 1/2. Where ever it was thinner it stayed thinner. All you had to do was run it in a 300 Weatherby die. So if you don't have extra clearance you may have to turn a little. Matt

 

[timeout]

Hey necking down 300 SAUM norma brass to 7mm SAUM, is it imperative to neck turn the brass ?
Will the necking down process cause the brass in the neck to become uneven ???
Does necking it down in two steps help reduce this ?

Cheers in advance Steff.

I have not necked down the particular caliber that you are asking about. That being said, I have found that necking down does increase neck thickness. If you do not have a case neck thickness micrometer, your best bet would be to seat a bullet into a dummy round and subsequently use a known properly calibrated, 0 to 1" mic, to measure the OD at the pressure ring. To be safe, you want a minimum .002" clearance between the neck of the loaded round and the neck area of the rifle chamber. Even if you have enough clearance, you may want to turn the neck slightly to eliminate any variation in neck thickness. I like the 21st Century turning tools that allow you to match the cutter to the shoulder angle of the cartridge case. By turning right up to the point the tool just starts to remove shoulder material I believe it will help to prevent "donuts" from forming inside the case at the neck-shoulder junction. Hope this makes sense for you.

 

[Shynloco]

I claim no expertise in this, but from what I've been told and read, anytime you neck up or down, it's a good idea to AT LEAST "clean up" the necks and turn them to make sure they are even and remove any donut that may have formed because of the necking process. Might be an idea just to experiment with your rifle and see if she likes a change (more than just cleaning up the neck). Also, sometimes turning brass will help you get to the .002 neck tension/thickness that many look for in their brass. Also be sure to check the concentricity once you do turn the necks to make sure you have .001 max run out on your casings that gives the accuracy. Just things to think about.

Alex

 

[rem 243]

Cheers guys,

All great information and greatly appreciated.

Cheers Steff.