Accuracy due to velocity, charge, or random...?

[MudRunner2005]

 

[crkckr]

I have tried matching velocities of an accurate load with a different powder and not had any luck at all. I suspect that anyone that does just has better luck than I do! I've had to repeat the entire process when changing powders for some reason. I will take a wild guess and say that the different burn rates between powders, even similar ones, are enough to cause a loss of accuracy. Sometimes the new powder simply won't shoot at all. Once in a while it does better, too, so I don't think there's any predicting how it will go. Ya pays yer money and takes yer chances!
Cheers,
crkckr

 

[FURMAN]

I have tried matching velocities of an accurate load with a different powder and not had any luck at all. I suspect that anyone that does just has better luck than I do! I've had to repeat the entire process when changing powders for some reason. I will take a wild guess and say that the different burn rates between powders, even similar ones, are enough to cause a loss of accuracy. Sometimes the new powder simply won't shoot at all. Once in a while it does better, too, so I don't think there's any predicting how it will go. Ya pays yer money and takes yer chances!
Cheers,
crkckr

Reread. The node is not 5fps. It is roughly 20-50fps IME. It it worked the way you expected we would all just run a faster burning powder to use less of it. There is not luck to it. It is physics.

 

[Canhunter35]

I have to laugh a little because in other threads you have acted as if you consistency shoot .1 groups and know all about tuning. Nodes absolutely exist and certain bullets prefer certain speeds from certain barrel lengths. If you really care to learn about tuning you would follow what 1000 yard BR guys or Fclass guys are doing. One of many examples is the 300 wsm with 210 VLDs or 215 hybrids will have a node around 2850-2900 from a 28-34" barrel. I have found that typical nodes are 20-50fps wide and about 100-150fps apart. It is going to pretty hard to see, in my opinion, from a rifle only capable of .75-1moa.

I agree with what you said and wanted to add: typically heavier barrels have wider nodes and the nodes are closer together IME.

To the op:
My 300wby is a sporter contour so the wall of the barrel is thin, making tuning the load trickier, there's a reason why I used 3 different powders trying to find the best es, because the es with 7977 it would literally take it out of the node and the shots that didn't group would be a really high or low velocity

 

[MudRunner2005]

I have tried matching velocities of an accurate load with a different powder and not had any luck at all. I suspect that anyone that does just has better luck than I do! I've had to repeat the entire process when changing powders for some reason. I will take a wild guess and say that the different burn rates between powders, even similar ones, are enough to cause a loss of accuracy. Sometimes the new powder simply won't shoot at all. Once in a while it does better, too, so I don't think there's any predicting how it will go. Ya pays yer money and takes yer chances!
Cheers,
crkckr

I've never tried to recreate a factory load... I just do my own thing, and work up a whole new load, which is almost always faster, and definitely more accurate than the factory fodder.

 

[crkckr]

Reread. The node is not 5fps. It is roughly 20-50fps IME. It it worked the way you expected we would all just run a faster burning powder to use less of it. There is not luck to it. It is physics.

I just replicated the exact same velocity with a different powder, as the OP suggested. I didn't say anything about a node, nor if I used a faster or slower powder (hint: I've tried both and still had no luck). When you have two velocities that match and one shoots and the other doesn't it's not physics it's freakin voodoo! Physics makes sense and has rules... rifles don't follow anyones rules!
Cheers,
crkckr

 

[skipglo]

Sigh.

1) I've never said they don't exist.
2) I suspect I have similar knowledge of harmonics to you, unless you're actually an engineer or physicist.
3) I don't build rifles, unless you count AR15s and slapping a drop in Shilen barrel onto a Savage LRH...

Would it be possible to get back to the substance of my original inquiry now? Or would folks prefer to keep valiantly defeating straw man caricatures of my opinions?

I will support you on this response. I didn't see where you stated ...they don't exist...you said...
You just can't find one! So my question....what gap are you using between your test bullets...as in...how many decimals of grains of powder? Your gaps may be too large to see the node.

 

[crkckr]

I've never tried to recreate a factory load... I just do my own thing, and work up a whole new load, which is almost always faster, and definitely more accurate than the factory fodder.

I have several firearms that have never seen a factory round, including my .338 WM, .308 (both of them) and the .270 Win. Only if I get weird signs of pressure or some other oddity will I get a box of factory ammo to compare things. Doesn't happen very often!
Cheers,
crkckr

 

[ar10ar15man]

very helpful at emptying your wallet and little else.
std ladder is cheaper and quicker.
bs on round robin bs fouled bore
wind is a bigger issue in load development

http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134

This will be very helpful in potentially taking you hand loads to the next level .

 

[FURMAN]

very helpful at emptying your wallet and little else.
std ladder is cheaper and quicker.
bs on round robin bs fouled bore
wind is a bigger issue in load development

I do agree the ladder is quicker and better but the OCW does work if you are limited on distance. I do not believe you need to do round robin. I would make sure the barrel is sufficiently fouled before starting either method. In every magnum I have ever shot it takes 8-10 rounds after cleaning before they will group tiny. As far as fouling effecting the load development I would agree that it will not as you progress through the shots. I have not seen it anyways.

 

[brutis.270]

After reading your post I went to the log book for my 338rum and found velocity for the same bullet 300gr Berger otm the sweet spot was nearly 100fps different from my retumbo and US869 loads. all else equal seating depth ,once fired brass shot on the same day ,and no cleaning between . From my experience the accuracy came from the lowest ES 10-15fps not a specific velocity. my rifle would typically cross two nodes or sweet spots in my workups before pressure signs

 

[entoptics]

Interesting results. Sounds like something as drastic as changing powder negates a recipe. This is sorta my experience too. I hope the brass change isn't as critical, but we'll see.

When you have two velocities that match and one shoots and the other doesn't it's not physics it's freakin voodoo! Physics makes sense and has rules... rifles don't follow anyones rules!

I gotta agree in practice. I'm sure there are rules, but tiny explosions in tubes just has too many of them to keep track of...

I've tried several ladder tests recently, with 270 and 300WM, and used 0.3 gr increments for a total velocity spread of about 75-100 fps. That range may be too narrow, but I tend to run rifles just under their max capability, and giving up more than 100 fps is hard to swallow, without some miraculous benefit.

My results showed no discernible pattern in the 300 WM, beyond "more powder = more speed". The 270 was utterly random. It's not that great of a shooter though, so I didn't expect to find a magic recipe.

At one point, for both rifles, I thought I was seeing something, so I repeated the tests to overlap the potential "node" and didn't see any sign of it the second time.

 

[FURMAN]

Interesting results. Sounds like something as drastic as changing powder negates a recipe. This is sorta my experience too. I hope the brass change isn't as critical, but we'll see.

I gotta agree in practice. I'm sure there are rules, but tiny explosions in tubes just has too many of them to keep track of...

I've tried several ladder tests recently, with 270 and 300WM, and used 0.3 gr increments for a total velocity spread of about 75-100 fps. That range may be too narrow, but I tend to run rifles just under their max capability, and giving up more than 100 fps is hard to swallow, without some miraculous benefit.

My results showed no discernible pattern in the 300 WM, beyond "more powder = more speed". The 270 was utterly random. It's not that great of a shooter though, so I didn't expect to find a magic recipe.

At one point, for both rifles, I thought I was seeing something, so I repeated the tests to overlap the potential "node" and didn't see any sign of it the second time.

What distance did you perform this ladder?

 

[entoptics]

What distance did you perform this ladder?

400 yds for all of them, though I faintly recall 500 yds for one of the repeat tests, simply because I already had a 500 yd target out there.