Precise bullet seating and crimping using computer control

[Josh]

I don't know much about reloading and am new to the subject. I read that for really accurate ammunition u want the force required to separate the bullet from the case to be of a value so that they separate when the gas pressure has reached the value required, optimum. So I want to have an assembly machine that can create a precise tension so that the bullet and case will separate at the desired force\pressure.

match ammo is almost never crimped. Neck tension is controlled by how thick the brass is in the neck and how much its sized down by the die vs the bullet used.

[sam007]

fairfaxjim, I want to be able to control the crimping force so that I know exactly what force will separate the bullet from the case mouth. I also want to be able to vary the crimp force so that I can have bullets separate at different pressures. Bullet seating depth also contributes to accuracy\performance of ammo, how? not sure . I would have to find out what precision of seating depth matters to accuracy. from what source I can found this out I don't know.
Do u have an idea to what accuracy a servo or stepper motor will be able to move?

[sam007]

josh so for non crimped ammo u are saying that the tension between the bullet and case is determined by the thickness of the case and the bullet as the tension is created by a forced fit between the two components. What about how deep the bullet is seated will this affect the tension between the bullet and the case?
josh, its a project for my final year university degree. I won't be making it just designing it. I wanted to design an ammo assembly machine that produces better accuracy and a machine that needs the minimum of retooling\resetting when another calibre is produced.

[sam007]

Just run over to Olin and pick up one of their used ammo machines out back
and throw some gizzmos on it.

http://www.youtube.com/watch?v=3AXANIjdrg0&feature=related

[Josh]

josh so for non crimped ammo u are saying that the tension between the bullet and case is determined by the thickness of the case and the bullet as the tension is created by a forced fit between the two components. What about how deep the bullet is seated will this affect the tension between the bullet and the case?
josh, its a project for my final year university degree. I won't be making it just designing it. I wanted to design an ammo assembly machine that produces better accuracy and a machine that needs the minimum of retooling\resetting when another calibre is produced.

Almost all ammo, the interference fit between the case neck and bullet are what determine tension.

The crimp is primarily to keep the bullet from moving around during recoil or feeding.

Crimp also deforms the bullet and can be detrimental to accuracy.

Bullet depth is a function of accuracy in how it relates to the chamber of the firearm. Seating depth determines how far the bullet has to jump to reach the lands of the rifling and can also affect chamber pressures.

Anytime you change one component it affects everything else when it comes to loading match ammo. For an easy way to adjust next tension automatically i would correlate the force used to seat the bullet with neck tension and design a finger collet type neck sizing die that can be adjusted in and out do vary the neck size.

[sam007]

That is another thing I need to find out which I haven't been able to find a source for the info. What level of precision in seating depth, tension between bullet and case mouth, amount of powder , will effect accuracy and to what degree I don't know yet. Another issue that can affect accuracy in ammo is the angle that the bullet is seated. Maybe it only really matters for sniping ammo.
so how could it be done with hydraulics or pneumatics?

[sam007]

josh, its mechanical engineering. As Isaid I don't know much about reloading. I have done some stuff on computer control and instrumentation to control mechanical devices such as a stepper motor and pneumatic pistons but other than that I don't have much experience in automated machinery and sensing. Anyways I am not making it. I will just design it and list the componnets needed to get it to work.

[Josh]

That is another thing I need to find out which I haven't been able to find a source for the info. What level of precision in seating depth, tension between bullet and case mouth, amount of powder , will effect accuracy and to what degree I don't know yet. Another issue that can affect accuracy in ammo is the angle that the bullet is seated. Maybe it only really matters for sniping ammo.
so how could it be done with hydraulics or pneumatics?

to give you a starting point, headspace for a firearm is usually measured to +/- .001in

powder is usually +/- .1 grains as that is what most digital scales are rated for.

neck tension is not usually measured as a force as it is changed with different size collets and the force a certain collet size will impart on the end result will vary with the properties of the brass, neck wall thickness and bullet sizing.

People usually try different collet sizes with the specific brass and bullet they are using untill they find a combination that works.

[westcoastr]

As a "recovering" engineer, I applod your efforts - I'm all for a cool new project. But I have to say that these days, with the stellar quality match/competition grade dies and equipment, your efforts will not likely be significantly helpful. That is: high-end reloading equipment will produce results more repeatable that is actually nessessary. the weak link these days are the components themselves (bullet quality, powder ("old" vs "new" Varget!!, and primer consistancy). and then there are the shooting conditions themselves. for example: wind can vary at different speeds and directions along entire path of bullet and this is impossible to detect w/o indicators set up every so often...