accuracy & 'Node'

[zdr]

I've been reading some of the info on here regarding 'nodes.' I am by no means an expert reloader - learning over the last few years really.
I just purchased my first chrono and tested some loads this week. My results are:
Set 1: V ave: 2622, ES: 27, SD 12.8
Set 2: V ave: 2690, ES: 104, SD 42.6
Set 3: V ave: 2699, ES: 28, SD 14.7
Set 4: V ave: 2738, ES: 103, SD: 45
Set 5: V ave: 2752, ES: 20, SD 8.2

Sets 1, 3 & 5 were similar in accuracy and no pressure signs (set 5 is slightly over book max).
I assume that these 3 sets are considered the load accuracy nodes? or would only set 5 be considered that? Or is it something else?

zdr

 

[Engineering101]

zdr

It is something else. Check out this link if you want to know about accuracy nodes.

Optimal Barrel Time Paper

Now that you have a chrono, you are only one tool (QuickLoad) and a bit of knowledge away from being able to master "node" theory.

 

[Deleted member 46119]

With the barrel length and the OBT table or spreadsheets, you will be able to determine the timing.

With QuickLoad, some simple measurements and data entry you will be able to model your load and QL can estimate the barrel time.

Then a little fine tuning.

Below is why...

It's really cool and using it I have been able to get acceptable accuracy for the task of that load in as few as 10 shots. I shoot alot and the price of QL is well covered by the savings in bullets, powder, primer and range time. Range time hitting the steel at 700 yards is the goal. Proving loads is fun but not as fun as whacking 5" dueling tree swingers at 700 yards. Well other than hunting and 1000 yard match's.

 

[zdr]

Thank you for the OBT link and QL recommendations. Much appreciated!

zdr

 

[Mikecr]

I think you should know it's a little more complicated than expressed so far.
There are pressure nodes, seating nodes, and barrel nodes, which are completely independent of one another.
Then you have compatability as an attribute between reloading components, brass, powder, primers, and bullets -to chamber & bore.
That is, some combination, which is in no way predictable, is best amidst other combinations. Some are terrible.
Every barrel is different & unpredictable until proven to be just what it is.

OBT is limited in accounting just as OCW(optimum charge weight) is limited.
Then there is the reality that most sources of advise don't even know the difference between accuracy and precision..

Given this, accuracy tuning where much is unknown, is not always easy, and there is absolutely no predicting of it. No magic shortcuts.
Search around a little bit, read some articles out there on the net. You'll see it can get complicated beyond luck.

 

[Engineering101]

Maybe Fred and I were lucky but I also have been able to work up loads that are very accurate and repeatable in as little as 9 shots using QuickLoad and a bit of powder burn rate calibration. I won't say that there is not a learning curve but it works for me and does save a lot of powder and bullets, not to mention barrel wear.

 

[dsculley]

Another good read on "nodes" is here: OCW Overview - Dan Newberry's OCW Load Development System

If you take the time to read this entire site and Chris Long's Optimum Barrel Time paper you will get a good understanding of what a "node" is. You can find a good node with more than one powder, bullet and primer combination. While there may be one "best" for your particular rifle, it is possible to shoot the barrel up trying to find it. For me at least, I try to use the slowest powder for the application that I can find available. Availability is the key right now.

As others have stated, a chronograph, Quickload and a good understanding of barrel harmonics will go a long way in finding a good node.

Dennis

 

[zdr]

Lots of good reference material...I'll be reading for a while...