Neck size

[Jeff Von Rosenberg]

Just double checking my math! With a reamer with a .300 neck size what should my loaded rnd with .002 neck tent ion be. Basically neck clearance plus neck tension . Thanks JVON not ignorant just checking!!

 

[jonbearman]

What kind of brass will you be using and what caliber? What wall thickness is it.

 

[kolar55]

If you're after .002 clearance I guess that would be .298. (.300-.002).

 

[Jeff Von Rosenberg]

I need chamber clearance also.

 

[Jeff Von Rosenberg]

John the brass is 22 WSSM .0180 before turning. Guess I need to know what I need to turn brass to to achieve proper clearance. I'm pretty sure I know but no harm in checking with the Gurus!!

 

[MrMajestic]

I need chamber clearance also.

JVON, you are reading way too much into this and the correct answer for your question the way it is written is in fact .298! If your reamer cuts a .300 neck and you want .002 clearance .300-.002=.298. Neck tension does not change the OD of the neck on a loaded round it changes the ID to achieve neck tension. Case neck thickness X 2 + Bullet diameter - .002=.002 neck tension on bullet.

 

[dkhunt14]

I always run 3 thousandths clearance. So a loaded round would be .297 and I would use a .295 bushing. Not sure if that is what you are looking for. Is this a 6.5 MM round? If it is brass would have to be 16.5 thousandths. Matt

 

[6BRinNZ]

JVON - the neck clearance is .300 - .002 = .298. I believe this is the answer to one part of your question. So your loaded round must = .298. The formula is (wall thickness x 2 + bullet diameter) - .002. How much you turn is dependant on what your loaded unturned diameter is. If that number was .300, you would want to turn .001 off the wall thickness .018 - .001 = .017.

However you are also asking for .002 neck tension which would be .298 - .002 = .296. This is your bushing or die neck size, and doesn't relate to how much you have to turn. It is purely impacted by the loaded OD. If you are using bushing dies then it would be advisable to get a bush .001 either side of .296 as well. This allows for you to cater for brass behaviour after sizing to achieve .002 neck tension.

If you end up sizing down by ~ .004-.005 then you most likely find the brass over sizes by .0005+

 

[Mega]

Don't forget to allow for bullets that have a pressure ring.