SIMPLE question on neck tension

[prostreet1]

I have read and view videos on bullet neck tension until I was dizzy. ( doesn't take much )

Am I over simplifying this or is this is what you need to know.

I understand that a lot of variables go into this.

Wall thickness, concentricity, straight parallel and all, but

The basic drawing I submitted, YES or NO!

Using .001 inch bullet tension as an example.

Any and all comments would be appreciated.

Thank You

 

[SilverbulletMAG]

What's the question?

 

[257Tony]

Neck tension is generally measured at the neck, after sizing the brass, and then after seating the bullet. Subtract the difference and that is it.

 

[ShtrRdy]

I think you have the right idea with what you said and drew.

 

[prostreet1]

I think you have the right idea with what you said and drew.

Thank you very much.

 

[prostreet1]

What's the question?

Do you make the case neck .001" smaller than the bullet diameter?

 

[sturner]

Deleted

 

[tim_w]

What everyone has said. You are not actually measuring any type of force so the term is not really very precise. It should be called "neck interference" but reloading being a laymans activity is full of these kinds of things.

The generally recommendation for starting point is .002-.003 interference ( neck diameter smaller than diameter with seated bullet or bullet + neck wall thickness×2)

 

[GLTaylor]

I believe most folks prefer at least .002-,003 neck tension for hunting rifles. If it's a heavy recoiling rifle, some use a bit more.

 

[SilverbulletMAG]

Do you make the case neck .001" smaller than the bullet diameter?

I think most would want at least double that but, as you said, many variables there at play.

 

[sturner]

U tube Panhandle Precision. Sam's got the best video on measuring neck tension

 

[AZShooter]

Everything you mentioned except the actual diameters were correct. Shouldn't a 30 cal bullet be .308"? So neck would be .001" less. Could also be called a press fit or force fit. .

Most RCBS FL dies I have used will produce a .003" difference between brass neck ID and bullet diameter. That is a good starting point for a hunting rifle. I would say that much more than that could cause enough pressure to induce runout with "bent" necks.

It is possible to go the other way with less than a .001" press fit with a single shot bench rifle called soft seating. The bullet is seated long and the bolt will push cartridge into chamber with enough force to push bullet into case so ogive of bullet is contacting the lands with same engagement for each round. Only issue with this minimal neck tension is if for some reason the shooter decides to remove cartridge without firing as it most likely will leave bullet in the barrel.

 

[codyadams]

Depending on the rifle/projectile/purpose, I start between .0015" and .0030". With my AR rifles and other semi auto rifles, I lean more towards the .0030" side of things, and may also crimp. With lighter recoiling rifles such as my 13.5 lb .260 AI with a brake, I start around .0015". My braked 9lb .338 NM has right at .0020" neck tension. After some load development is complete, I may tweak the amount of neck sizing (I use a full length bushing die so I also bump the shoulder after about 3 fireings) to see if it helps accuracy/consistency of my load if I feel it is necessary, but those are my general starting points.

You drawing is correct in it's theory. I measure as previously stated, measure after sized, then again after the bullet is seated and subtract the difference.

Want to really confuse yourself? Start trying to figure out the correct amount of distance down the neck you should size with your bushing!!!

 

[rammac]

This isn't rocket science.

The bullet's diameter should be a couple of thousandths bigger than the inside diameter of the case neck. The more the difference the tighter the fit.