trimming brass

[44 AMP]

An added 0.002 inches in trim length increases the velocity of the round by about 1 fps.
Shooting a cartridge with the exact same seating depth with a variation of 0.010 would mean that you would have a difference in 5 fps in muzzle velocity.

Where does this come from??

Not that it really matters, its meaningless data, even if it is correct for some specific instance.

 

[Rimfire5]

44 AMP

I assume you are referring to the relationship between trim length and velocity.
Try using QuickLOAD and adjusting just one parameter.
It tells you a lot about what happens when you adjust one thing.

Interestingly, a 0.010 increase in seating depth makes the same adjustment in velocity in the opposite direction.

It only matters if you are a precision reloader.
As I indicated, most would never even notice the difference.

 

[RC20]

And the one thing it changes you can't see in the noise level (variation) of other causes.

Kind of one of those, ok, we can ignore this if it comes up

Think about it, aside from things like expander ball dragging in the necks of bottle neck cases, what sizing does is squeeze a brass tube (closed at one end) SMALLER in diameter. This results in the "tube" getting LONGER.

I do get around the expander ball by using an M die. Vastly smoother and I think better.

 

[Paul B.]

I process my brass whether brand new or once fired the same way. First I resize, then trim and chamfer the neck. The I ream the inside of the flash holes and uniform the primer pockets. Fortunately the last two only need being done one time only. Why? To make my brass as uniform as I possibly can within reason. Usually after that I only need to trim after every third to fifth reload depending on the cartridge. Some stretch more than others due to their design.
Paul B.

 

[hounddawg]

SAMMI Specs are 2.015 -.020 which means the maximum is 2.015 the minimum is 1.095. it is just as easy to trim to 1.095 as it is to trim to 2.015 and you won't need to trim so often

 

[USSR]

Some people turn neck and use bushing dies though. I want to try it eventually. How does that effect neck growth I wonder

Shadow,

I've done both of the above, and there is no difference; brass grows.

Don