7mm-08 Improved help...

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std7mag

New member
Ok, so I did the rechambering of my Stevens 200 in 7mm-08 to 7mm-08 Improved 40 degree.

Chamber is done, so no need for discussions on that issue, please.

I fired a box of PPU ammo through it today, and the casings turned out beautiful!

Was looking at some of the load data for the 7mm-08 Imp.
Had to add cartridge to Quickload. Pretty much used the standard 7mm-08 listing, and refigured for my weight in grains of water to overflowing.
On +0.2 grain difference between standard 7mm-08, and 7mm-08Imp.

I took one of my old casings(again PPU). Tared it, and loaded to top of neck with RL19. 53.4gr.
Did same with fireformed casing, and got 53.2gr. :confused:

What the heck is going on???
Everything I've seen for load data on the Improved chambering is 4-5gr. more than a standard 7mm-08.

Some help explaining this would be GREATLY appreciated!!!!!

Thanks

Std7mag
 
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Snyper

New member
What the heck is going on???
Click to expand...
There will always be variations when measuring by volume

To prove it, fill a case as full as you can, then vibrate it or just tap the side a few times and watch the powder settle and make room for more

It's nearly impossible to be 100% consistant in how you fill a case
 
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Bart B.

New member
There'll easily be a 3% spread in case volume between when its new and after being fired. Best results comparing case volume is when all cases have the same outside dimensions. Otherwise, volume will vary with case weight, dimensions and how much out of round each one is.

I tried sorting case by volume and weight. No difference in accuracy with a 1% spread in either one; very little difference with a 2% spread and only then at ranges 500 yards and greater. Weighing cases takes a lot less time and is a lot less messy.

Sierra Bullets gets 1/4 MOA accuracy with their best match bullets at 200 yards and doesn't sort their test cases by any property nor prep them in any way.

That aside, if such measuring makes you feel better, do it.
 
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std7mag

New member
Yes, but I'm not talking about the capacity/volume of a fired 7mm-08, and an unfired 7mm-08.
I'm talking about the volume difference between a standard round, and an Ackley Improved fireformed casing.
 
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HiBC

New member
STD 7,I may be able to give you a clue.

How did you determine the water capacity of your PPU brass before you fireformed it from new factory ammo??

Do you by any chance have a piece of fired PPU brass from the original,non AI chamber?

If so,without decapping or sizing,slightly egg shape the as fired neck.It needs to hold a bullet,yet leak water past the bullet.
Take one case,as fireformed,not sized,not decapped AI brass.Egg shape the neck on that case,too.

Weigh both cases,write down the weight.

Weigh two bullets,write down the weight.

Fill the cases with water.Then seat a bullet to your loaded depth.

Now weigh the water filled loaded rounds.Write that down.

Now clean up the water and make sure your dies won't rust.

Now play with your numbers.
 
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steve4102

New member
I'm surprised you had to "add" the 7mm-08 AI to your Quickload. Mine has always had it.

Do as suggested and test your case capacity of a "fired" case in grains of H20. Also make sure your fireformed and standard cases are the same length. Fireforming can often times cause the case to be reduced from head to case mouth.

Here is my version of QL. I did not add this, always was.

Screenshot%203_zpseakj0mtq.png
 
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