neck-sizing

[Col]

Hi guys. Could someone please explain to me the theory behind bumping back
a case which has been necked sized 3-4 times.I understand that as the rifle fires the brass flows towards the neck and that occasionally the case needs to be shortened back to size,but if the case has fire formed to the chamber,and I assume fills the space between the bolt and the chamber how exactly does it lengthen enough to stop the cartridge from loading. I know it happens,it has to me,,but I just cannot get it into my head as to how

 

[Walkalong]

There are multiple threads on this, many of them here lately.

The brass is hammered by pressure to fit the chamber shot after shot, and eventually it becomes work hardened, fits very tightly, and extraction/chambering gets sticky.

That is when the body and shoulder need a little sizing. I would rather just partial full length size every time for anything but true match rifles. Even then, using a bushing die with a custom sizer set to barely size is the way to go, but some people neck size with a bushing die, and use the body die when they need to.

 

[fguffey]

reloaders exemption, size the body without moving the shoulder? Bump the shoulder..

Beats me, I have often wondered, for sure they do not purchases cases from the same place I purchase my cases, I fire a case 5 times and get 5 time fired cases, there is no way I can start over by full length sizing, I have often wondered, is there a place like the one Jack got his magic beans, a place that sells magic cases?

No one will consider the effect hammering on the inside of the case has on working the brass, during manufacturing when the case is formed, from start to finish, the case is annealed at least 5 times, with the way some of of the stories told by reloaders one would think reloaders have an exemption to all the rules.

Bump? To me? Bump sounds like an accident, I do not have less than 10 presses, some bump, some do not, all my presses that bump, bump twice. For me, nothing is gained by standing on the handle because of bad habits, again I do not abuse the press, by design, the press wins, if it does not there is the feeler gage, the standard, the transfer, the companion to the press, Redding calls it a thickness gage.



I do not bump, I control the distance from the deck of the shell holder to the shoulder of the die, if the case shoulder of the case hits the shoulder of the case, the shoulder moves back, when the shoulder moves back the case body increases in diameter, with out case body support the shoulder can not be bumped back without causing an increase in the diameter of the case (back to fire forming and keeping up with two thoughts at once), A fire formed case fits the chamber, if when bumping? the case expands the case will no longer fit the chamber it was fired in. I can use a 'BUMP PRESS' to size cases without throwing a press into a 9 line bind, it is all in timing and knowing your press.

And there is "TIME IS A FACTOR", a term wasted on those that purchase their cases from the same place Jack got his beans.

There is case stretch, there is case flow, or is it stretch and flow, or one or the other? The outside of the case lock onto the chamber, what doe the inside of the case lock to? If the outside of the case locks onto the chamber and stretches and or flows, where are the skid marks?

I am not a fire former, I form first then fire, to form first the reloader must know the length of the chamber before firing.

F. Guffey

 

[gamestalker]

By partial resizing fire formed brass, you are reducing the shoulder, or wall and shoulder, by just enough to allow the case to once again fit the chamber.

As Fguffy stated, some of us fire form, and others form first. After years of pushing shoulder's and walls back when necessary to facilitate normal chambering, I am now seriously considering the form first method as it just makes more sense.