Neck constriction?

[erickg]

Been reloading now for 20 years and thought I had a pretty good handle on most aspects, doing some web surfing can really bring you back down to earth in a hurry though. Anyway saw a reference to .003 neck constriction on another post and was wondering if anybody could shed some light on the meaning of this. Also, dose anybody use a bushing neck sizing die, and if so have you noticed an improvement in accuracy enough to justify the additional cost. As my collection of custom barreled rifles grows I'm looking to have my knowledge of reloading and reloading methods grow as well.

 

[rscott5028]

Neck constriction is unfamiliar terminology to me.

I suppose you're asking how to achieve ideal neck tension on the bullet?

Bushing dies as well as collet dies can assist by constricting the ID of the neck .002-.003" smaller than the OD of your bullet. The brass will spring back to .002-.001" smaller than the bullet which is considered by many to provide the ideal amount of neck tension for seating your bullets.

-- richard

 

[Edd]

Anyway saw a reference to .003 neck constriction on another post and was wondering if anybody could shed some light on the meaning of this.

I don't know the context of the discussion in that other thread but I think i can explain neck constriction. It is a condition where the brass is not the same thickness for the full length of the neck. This usually happens when forming a case to something different than it's original size. An example would be if you shortened a case or did some type of reforming that would result in part of the original shoulder being moved to the neck. Since the brass is thicker on the shoulder than the neck and the reforming leaves the outside of the neck the same diameter, the inside of the neck will be a smaller diameter, constricted, as you get closer to the neck shoulder junction.

 

[rscott5028]

I don't know the context of the discussion in that other thread but I think i can explain neck constriction. It is a condition where the brass is not the same thickness for the full length of the neck. This usually happens when forming a case to something different than it's original size. An example would be if you shortened a case or did some type of reforming that would result in part of the original shoulder being moved to the neck. Since the brass is thicker on the shoulder than the neck and the reforming leaves the outside of the neck the same diameter, the inside of the neck will be a smaller diameter, constricted, as you get closer to the neck shoulder junction.

Now you're talking about the dreaded doughnut... Perhaps that was the original context?

 

[djtjr]

Neck constriction is unfamiliar terminology to me.

I suppose you're asking how to achieve ideal neck tension on the bullet?

Bushing dies as well as collet dies can assist by constricting the ID of the neck .002-.003" smaller than the OD of your bullet. The brass will spring back to .002-.001" smaller than the bullet which is considered by many to provide the ideal amount of neck tension for seating your bullets.

-- richard

Richard has it + 1 though I find spring back will usually be a lot less than .001 anything more than .003 really has diminishing returns as the bullet just expands the brass and doesn't offer much more hold. I use .001 for bench and single shots .002 for most mag fed hunters and .003 for real heavy recoilers with a mag also some use this for autoloaders so it depends what u r trying to do and as always there are no absolutes each gun will like it different.
Good luck
Don

 

[Edd]

... Perhaps that was the original context?

I was just guessing. I figured he would understand tension.

 

[erickg]

The context was a guys method for loading .223 AI.

 

[Edd]

The context was a guys method for loading .223 AI.

Then you should probably ignore everything I said. They were most likely referring to the difference between the diameter of the bullet and the diameter of the inside of the case neck. If the inside diameter of the neck is .003" smaller than the outside diameter of the bullet you could say it had a .003" constriction. I suspect different people call it different names based on their environment. I've always just called it press fit.

 

[erickg]

And would this precise level of constriction be obtained using a bushing type sizer?

 

[rscott5028]

And would this precise level of constriction be obtained using a bushing type sizer?

Yes. That's one way to control it.

 

[rscott5028]

...but, you first need even neck wall thickness to manage it consistently.

This is accomplished using high quality brass and/or neck turning.