How much is enough?
Thinking Big Bores only.
In the old days they would indent the case into the bullet.
How much neck length do you need if you crimp?
Shouldn't recoil velocity be a factor in the computation?
How much surface area is required to secure a bullet?
What is a minimum workable ratio of neck length to bullet diameter?
Should we factor in irregularities of brass thickness or bullet material/s?
Has anyone tested the force it takes to push in or pull out a bullet?
How much resistance is necessary?
Not all crimps are created equal.
Some bullets do not have the same surface area due to bands.
Don't get me wrong, I like giraffe cartridges.
Any Big Bore Myth Busters out there?

I don't think there is a true formula for neck length, as you know, early cartridges had necks that the bullet would not fill, at least a quarter was free of any bullet shank.

It was soon discovered that a shorter than bullet diameter neck length still worked and did not impinge on accuracy, this was thought to impact accuracy negatively at the turn of last century.

The old way of crimping was not very well done, I have several boxes from around 1915 made by Kynoch in 416 Rigby that the bullets rattle in the necks and the only thing holding them in place is the crude 3 depression type crimps in the neck. I am a shooter more than a collector, and I shot a few of these and they were inaccurate to say the least, good enough for buff or ele hunting I guess.

I have tested the force on bullet seating, no relationship between accuracy and the force needed to seat the bullets was found, BUT some cartridges/rifles like a lot of tension, and some like a little.
It must be understood that neck tension only influences start pressure for a few milliseconds, as soon as the primer ignites the pressure generated is already effecting the neck expanding it. Bullets are not held throughout the powder ignition, it is released early on in the burn and neck tension is not what guides the bullet from the case, it is the throat that does so.

Cheers.

Use a taper crimp die..it has much more to offer, without going into detail...A tight crimp can up pressure as much as 2000 PSI im told, but thats not enough to endanger a shooter with a properly loaded round.

Soooo a taper crimp with how much for a minimum neck length? Or how small is too small? Is 1/4 of the diameter of the bullet too small? 1/3?

If you can push the bullet against your reloading bench hard with the heel of your palm without budging it you have enough neck tension. The crimp is practically ornamental after than.

On the other hand, if you don't have enough neck tension, crimping won't help much.

I like to seat bullets to a depth of one bullet diameter. The neck doesn't need to be longer than that, IMO.

The rule of thumb that I have always applied is that the neck length should be at least the bullet diameter. I have no idea where I got it. I have always applied it to the wildcat cases I have designed, such as this one:

quote:

Originally posted by xausa:
The rule of thumb that I have always applied is that the neck length should be at least the bullet diameter. I have no idea where I got it. I have always applied it to the wildcat cases I have designed, such as this one:

This is what was thought to be the influence to accuracy, which has been proven to be incorrect.

To the OP, it has been proven time and time again that as long as the bullet doesn't fall out or get pushed back into the case a bullet can have a 1/4 of it's diameter in the case with no problems.
I shoot 75gr HP bullets in the 25-06 with about .120-.130" of the bullet heal in the neck, this shoots very small groups and is my long range fox outfit, you guys would use it for coyotes with spectacular results.
The old notion that it was the neck that kept the bullet straight and true on it's journey to the rifling is simply not the case, it's the throat or leade that does this.

Cheers.

quote:

The old notion that it was the neck that kept the bullet straight and true on it's journey to the rifling is simply not the case, it's the throat or leade that does this

I would venture a bet that there are many would disagree with this statement

There are literally volumes written, pontificated studied and experimented with when it comes to the subject of case neck tension and concentricity of bullet engagement with the bore and ultimately precision ! Both in lay and scientific literature.

quote:

Originally posted by ALF:

quote:

The old notion that it was the neck that kept the bullet straight and true on it's journey to the rifling is simply not the case, it's the throat or leade that does this

I would venture a bet that there are many would disagree with this statement

There are literally volumes written, pontificated studied and experimented with when it comes to the subject of case neck tension and concentricity of bullet engagement with the bore and ultimately precision ! Both in lay and scientific literature.

Breech seating match shooters would disagree with those studies, wouldn't they?

Careful with too much neck tension through crimping I have learned.
I had some nice 450 gr 458 loads blow primers out because I over crimped them without properly centering the crimp in a canelure on a Barnes TSX
I prefer the Lee Crimp Die as it is easier to feel how much crimp youre putting on the bullet.