What has your experience been with the spacing between tuning nodes?

[BoydAllen]

If a load is perfectly in tune, and you increase or decrease your charge weight until it is again in perfect tune, what is the difference between peak tune charge weights? Be sure to list the caliber and bullet weight you have use for this determination. Thanks.

 

[RegionRat]

About 1.5 grains of Varget apart in 6 Dasher with Berger 105 hybrids, or roughly 100 fps apart for powder nodes.

 

[Clancy]

I can’t say for certain about the amount of powder, but certainly agree that it seems to come and go in 100 fps windows.

 

[Ranger188]

.6g

 

[Chris Edmondson]

Not scientific by any stretch but, here goes.

6.5 Creedmoor, 140gr Hornady BTHP, H4350, CCI BR2, 0.023" OTL seating.

Sig SSG 3000, Benchmark 24" barrel.

A load ladder showed POI at 10:00 o'clock with 41.1 gr, POI at 5:00 o'clock with 41.3 gr. Both were excellent 3-shot groups, <.25 MOA at 200 yards. After shooting two sets of 5-shot groups on different days, 41.3 gr appears stable at 3:00 o'clock, holding 1/2 MOA-ish groups. It may be a narrow node but the median velocity of 2750 fps is a well-known velocity node for the caliber.

Convergence to a seating depth and charge took roughly four sessions and 150 rounds downrange, not cheap, not fast but, I feel confident anything that goes haywire now will be caused by the triggerchimp :0

 

[Doom]

I use OCW in 223 and 308 and have found that "nodes" tend to be around the 3% of charge that Dan Newberry quotes, with one possible exception. In 308 with a 168 SMK I seem to have nodes at 43.4 and 43.8 gr of IMR 4064 in Win brass. I never took the 43.8 out to test at distance beyond 300 yds, so I don't know if it would hold or not.

 

[Ackman]

Don't remember what the spacing has been, several different rifles. But here's something I'd never experienced before. Fireforming a 6BRX. These is first time shooting this one. Except for the 1st group, top left which is 3 shots and mislabeled, all are 2 shot groups. Again, this was to see what the new rifle would do.. And 75yds because of a peculiarity of the range. Even at 75yds this kind of accuracy over 1.2gr, fireforming, was a nice surprise.

 

[BoydAllen]

.6g

Caliber?

 

[RDavies]

Ive always worked on about 120 fps between nodes

 

[CharlieNC]

I use OCW in 223 and 308 and have found that "nodes" tend to be around the 3% of charge that Dan Newberry quotes, with one possible exception. In 308 with a 168 SMK I seem to have nodes at 43.4 and 43.8 gr of IMR 4064 in Win brass. I never took the 43.8 out to test at distance beyond 300 yds, so I don't know if it would hold or not.

In addition to working with hundreds of long range students annually, Dan also does ocw load development consulting. In other words he has an enormous data base from which to develop these guidelines. Bear in mind that he defines a node based on stable vertical poi, not group size as a bench rest focus.

 

[Field_2_Fork]

The common theory from some of the top shooters in my area is that nodes are spaced approx 1.2 grains, 6PPC with N-133.

I haven't tested this yet, several other things I'm more concerned about at the moment, but that's what they say.

 

[RegionRat]

In addition to working with hundreds of long range students annually, Dan also does ocw load development consulting. In other words he has an enormous data base from which to develop these guidelines. Bear in mind that he defines a node based on stable vertical poi, not group size as a bench rest focus.

I agree.

It can take watching dozens and hundreds of barrels to get a clear picture of how a particular design's characteristics develop into a recognizable, useful pattern. When the design is good, and the QC is tight, the patterns can show up sooner.

And, if there is then a variety of designs going past, you have to try your best and tease out the characteristics of the barrel and recipe combinations without the benefit of a mountain of data to stand on. That is where his experience pays off. YMMV