.264 Win Mag, Barnes 120gn TSX, Retumbo - target analysis

[Shinbone]

Hi All,

This is my first serious effort at loading my own ammo, and also at shooting something besides simple groups to find the best load. This being a culmination of my reloading bench build, seen here:

http://forum.accurateshooter.com/threads/reloading-bench-build.3975916/

The gun is a Winchester M70 Extreme Weather in .264 Win Mag w/26" barrel. Ammo parameters are Barnes 120gn TSX; 0.050" jump; Retumbo in 0.5gn steps from 61.0gn to 66.5gn; Hornady virgin brass; Federal 215M primer. Distance is 100yds. 2 shots per load.

The target:


This graph is of height-above-POA vs powder charge:


This graph is velocity vs powder charge:


To my amature eyes, the height-above-POA graph shows a strong node at 62.5gn -- 63.0gn, and somewhat of a node at 63.5gn -- 64.5gn.

The velocity graph shows a strong velocity node at 62.5gn -- 63.0gn, and a node at 64.0gn -- 64.5gn.

Correct?

Looks like the best place to further develope would be the 62.5gn -- 63.0gn charge weight range. And, 64.0gn -- 64.5gn, may be worth further development.

There were no signs of pressure at my highest charge weight of 66.5gn. The Barnes website shows 67.6gn as max charge, so I will load up some rounds approaching that weight to see if there is another node at a higher velocity before further developing either of the above nodes.

Make sense?

 

[Bc'z]

I like the top left 2 targets split the difference on charge and fine tune seating.
Center row 3 targets on left great horizontal, agian middle charge and fine tune seating.
I know components aren't cheap, but shoot at least 3 next go around.

 

[corsair4360]

I cannot see how two shots tells you much... I use 3 shots on my hunting rifles and often repeat the three shots to get a better idea of what is going on. Often my hold etc are at fault especially on hunting rifles

 

[Bc'z]

I cannot see how two shots tells you much... I use 3 shots on my hunting rifles and often repeat the three shots to get a better idea of what is going on. Often my hold etc are at fault especially on hunting rifles

Look at it as a horizontal ladder

 

[Shinbone]

Look at it as a horizontal ladder

That is a good way to put it. I've never shot a ladder test, before, so I kind'a cheated by making it a combination ladder and shooting groups. Plus, I was shooting at only 100 yds.

And, I know you get better statistics with more shots in the group, but for the first run with this gun, I did 2-shot groups just to get a coarse idea of what it could do. In other words, while it takes a 5-shot group to test for accuracy, it only takes a 2-shot group to test for inaccuracy.

 

[Bc'z]

That is a good way to put it. I've never shot a ladder test, before, so I kind'a cheated by making it a combination ladder and shooting groups. Plus, I was shooting at only 100 yds.

And, I know you get better statistics with more shots in the group, but for the first run with this gun, I did 2-shot groups just to get a coarse idea of what it could do. In other words, while it takes a 5-shot group to test for accuracy, it only takes a 2-shot group to test for inaccuracy.

I'd take a closer look at second target from left middle row. The first 3 are showing alot of horizontal with minimal vertical. Middle target is pretty tight and if velocity is good for you I'd go to seating. IMO

 

[Shinbone]

Bc'z - thanks for you input.

 

[Rdlningcltchdmpr]

Hi All,

This is my first serious effort at loading my own ammo, and also at shooting something besides simple groups to find the best load. This being a culmination of my reloading bench build, seen here:

http://forum.accurateshooter.com/threads/reloading-bench-build.3975916/

The gun is a Winchester M70 Extreme Weather in .264 Win Mag w/26" barrel. Ammo parameters are Barnes 120gn TSX; 0.050" jump; Retumbo in 0.5gn steps from 61.0gn to 66.5gn; Hornady virgin brass; Federal 215M primer. Distance is 100yds. 2 shots per load.

The target:


This graph is of height-above-POA vs powder charge:


This graph is velocity vs powder charge:


To my amature eyes, the height-above-POA graph shows a strong node at 62.5gn -- 63.0gn, and somewhat of a node at 63.5gn -- 64.5gn.

The velocity graph shows a strong velocity node at 62.5gn -- 63.0gn, and a node at 64.0gn -- 64.5gn.

Correct?

Looks like the best place to further develope would be the 62.5gn -- 63.0gn charge weight range. And, 64.0gn -- 64.5gn, may be worth further development.

There were no signs of pressure at my highest charge weight of 66.5gn. The Barnes website shows 67.6gn as max charge, so I will load up some rounds approaching that weight to see if there is another node at a higher velocity before further developing either of the above nodes.

Make sense?

First, go down to the 100ttsx as it wins in every respect. Second forget the half grain stuff. Go up in one grain increments and many of my best accuracy loads are at max or one grain over. Pm me with question's

 

[DUSTY NOGGIN]

if you are saving life / wasted components i would agree ... but when im looking for a result on a new to me rifle , i want all the data i can get from the same day from the same shooting position... im on the other side of the fence , and even drop it to .3 on rough load test shooting up to 4 shots depending on cartridge , i prefer the idea of getting all the accuracy and inaccuracy data all on the same trip , you can lose/confuse alot of info based on a different days conditions and shooting conditions