Case sorting???

[elkaholic]

J.E. The method you described is EXACTLY how I measure the cylinder "and head" volume of my hot rod snowmobiles and they have a lot more displacement than a cartridge case (unless it's a 155 howitzer). The question I have is: what is acceptable variation in your opinion?.........Rich

 

[J E Custom]

J.E. The method you described is EXACTLY how I measure the cylinder "and head" volume of my hot rod snowmobiles and they have a lot more displacement than a cartridge case (unless it's a 155 howitzer). The question I have is: what is acceptable variation in your opinion?.........Rich

That is where I learned also (Race engines).

The max exceptable to me is less than one grain in a batch

If I am going for all out performance I seperate the 1 grain max batch to Zero difference for
enough cases to shoot a match or group.

I also sort these by there concentricity and if I can come up with enough "Perfect" cases I can see
just how well the rifle will shoot (In my hands).

Just the way I do it.

J E CUSTOM

 

[elkaholic]

thanks, that's kind of what I attempt to do as well. I haven't found the weight of the brass alone to be a very consistent method..............Rich

 

[davewilson]

JE, i'm not going to argue that what you're doing isn't a more precise way of measuring volume. but i don't buy that there are inconsistant voids between the balls of powder. i've rechecked individual cases many times and come up with the same measurement every time. i remember reading about water volume testing and one of the limitations is the smaller a volume you're measuring compared to the surface area, the less efficient it becomes. like rifle cases. very small volume compared to the surface area.

 

[J E Custom]

JE, i'm not going to argue that what you're doing isn't a more precise way of measuring volume. but i don't buy that there are inconsistant voids between the balls of powder. i've rechecked individual cases many times and come up with the same measurement every time. i remember reading about water volume testing and one of the limitations is the smaller a volume you're measuring compared to the surface area, the less efficient it becomes. like rifle cases. very small volume compared to the surface area.

No problem. It is still a discussion as far as I'm concerned.

The best way to demonstrate the change in the consistency of the powder is to use a drop tube.

I use to compress some of my powder charges to get the amount of powder that I needed
in a case. while doing so I could hear some grains crunching. A friend older than me told me that
it was not good because it could change the burn rate of the powder and that I should use a drop
tube. when I did I was astounded at the difference.

I filled a case to the top of the neck just like you would when volume testing. Then I dumped this
powder in my powder scale pan and proceeded to pour it through the drop tube into the same case
that was full, when I finished , the powder was below the neck into the shoulder. Now i shoot the
same powder charge without any compressed loads.

So if the same amount/weight of powder can change volume that much you can see why I was
concerned about consistency.

And you are right about the small cases being more difficult to measure but it is mainly a
percentage difference but if you use the right Buret with smaller measurements it is very
accurate.

J E CUSTOM

 

[elkaholic]

Jerry....I too was amazed the first time I used a drop tube! It's difficult to believe without seeing and affects some powders more than others......Rich

 

[Hookturnr]

Call me stupid if you will but.....During the pressure event of firing the loaded round in the gun, wouldn't all cases regardless of previous volume then be expanded to the walls of the chamber of the rifle and thus have an exactingly consistent volume from round to round during the pressure event? The only thing left to change case volume at this point would be the dimensions of the base and web and this should be easily found via weight sorting I would think

just a thought..

 

[gr8whyt]

Call me stupid if you will but.....During the pressure event of firing the loaded round in the gun, wouldn't all cases regardless of previous volume then be expanded to the walls of the chamber of the rifle and thus have an exactingly consistent volume from round to round during the pressure event? The only thing left to change case volume at this point would be the dimensions of the base and web and this should be easily found via weight sorting I would think

just a thought..

Except for variances in case wall thickness from round to round. That's where brands and lots make quite a difference.

-- gr8whyt

 

[Hookturnr]

I agree that there are differences from one lot to another as well as from one brand to another.
This thread has been debating sorting your cases by volume OR sorting by weight.
My point is that if you weight sort your brass and eliminate the outliers, then you should be able to keep a very consistent load regardless of the volume meaasurement because all of the remaining cases will be expanded to a near identical volume during the pressure event. The only variable concerning the case during the pressure event would be the thickness of the base and web and if you already weight sorted then you should have minimized that variable.

I agree that case wall thickness does make a difference in volume but that variable should have already been nearly eliminated by staying with the same brand/lot of brass.
I shoot several different brands of brass in my rifles and have found some have drastically different volumes whereas others are nearly identical. My 300 RUM loads are approx. 1.5gr different between nosler and remington brass, however my 25-06 loads stay identical in both remington and hornady/frontier brass with identical accuracy and identical velocity averages. Thus my conclusion is that the base/web construction of both in 25-06 is nearly identical and my weight sorting has eliminated the cases with a thicker/thinnner base/web than the average of the lot.
Over all, I just don't see how you can derive any true value from volume measurements of the case when the volume is going to change to chamber dimensions the instant you pull the trigger.

 

[elkaholic]

I agree that there are differences from one lot to another as well as from one brand to another.
This thread has been debating sorting your cases by volume OR sorting by weight.
My point is that if you weight sort your brass and eliminate the outliers, then you should be able to keep a very consistent load regardless of the volume meaasurement because all of the remaining cases will be expanded to a near identical volume during the pressure event. The only variable concerning the case during the pressure event would be the thickness of the base and web and if you already weight sorted then you should have minimized that variable.

I agree that case wall thickness does make a difference in volume but that variable should have already been nearly eliminated by staying with the same brand/lot of brass.
I shoot several different brands of brass in my rifles and have found some have drastically different volumes whereas others are nearly identical. My 300 RUM loads are approx. 1.5gr different between nosler and remington brass, however my 25-06 loads stay identical in both remington and hornady/frontier brass with identical accuracy and identical velocity averages. Thus my conclusion is that the base/web construction of both in 25-06 is nearly identical and my weight sorting has eliminated the cases with a thicker/thinnner base/web than the average of the lot.
Over all, I just don't see how you can derive any true value from volume measurements of the case when the volume is going to change to chamber dimensions the instant you pull the trigger.

You would THINK that would be true, but the difference in wall thickness, etc. can, and does, make a difference. It is true that you eliminate a lot of the difference by weighing the same lot out, but if you volume measure as J.E. described, you will STILL find some of the cases with different volumes.
ALSO: I noticed in my previous post that I said weighing to be "consistent" and what I meant to say was "inconsistent" Sorry about that.....Rich