How important is one kernel of powder?

[Alex Wheeler]

Here's a 1,000 yard "ladder" ran round Robin over around a 30 second time frame for all shots. I guess the answer could vary, depending on where you are within the tune. This is a 6 bra with h4895, so each increment is about 6 kernels.

Tom

View attachment 1280478

Look at that target. That barrel broke an agg record, so it's a good barrel. How big is the node? Distances matter here so keep that in mind.

 

[JFrank]

Nice little overlap too, that higher node is deadly.

 

[tom]

Look at that target. That barrel broke an agg record, so it's a good barrel. How big is the node? Distances matter here so keep that in mind.

That barrel got ruined in one match, but did get a national group trophy. That ladder was in January at deep creek, before I knew her limits. Here was a follow up in April, once the temperature became a bit more reasonable, and barrel speed had settled. It had right around a 8 kernel window like every other 6mm barrel I've ever tuned with 4895 at 1,000, lol.

 

[Alex Wheeler]

Oh that was the Broughton, I was thinking it was a different one. Still a good one, probably better than the one I had in mind. But still a very good example of a normal "node" width for a 6mm at 1k. The only way your getting a .5gn. node at 1k is if your ok with 1/2-1 moa groups.

 

[Ccrider]

That barrel got ruined in one match, but did get a national group trophy. That ladder was in January at deep creek, before I knew her limits. Here was a follow up in April, once the temperature became a bit more reasonable, and barrel speed had settled. It had right around a 8 kernel window like every other 6mm barrel I've ever tuned at 1,000, lol.

View attachment 1281818

Please expound in how the barrel “got ruined.”
Btw, thanks for the informative response regarding your experience with 6mm barrels. Hope the op did not miss it.

 

[tom]

Please expound in how the barrel “got ruined.”
Btw, thanks for the informative response regarding your experience with 6mm barrels. Hope the op did not miss it.

I took one gun to an event I should've taken 6 guns to lol. It got a touch warm. May set it back one day as it's the throat that takes the beating.

Tom

 

[BoydAllen]

Even though I have not, and currently do not shoot long range, I HAVE done some experimenting that relates to this issue. I have tuned several balance scales so that they repeat very well. Using one of these, and a web cam set very close to to the beam pointer and scale, observing the image at several X magnificaton, I can easily read the scale to .05. Looking at the targets that have been provided it would seem that with a node of much width, that that would be sufficient for many purposes, including some initial dabbling at 1K. On the other hand, if long range shooting became a serious pursuit, at minimum a milligram magnetic force restoration scale would be my choice. Currently, a friend is testing a new .0001 G scale that falls in the same general price range as those those in common use. If he likes it, I will try to get him to do a report.

 

[RegionRat]

0.0001 gram = 0.0015433 grain , So roughly speaking that splits the tenth of a grain issue into 65 parts.

 

[BoydAllen]

On the subject of node width, have any of you who regularly compete at 1K seen or heard that adding weight at the muzzle can broaden nodes? I am talking about tuning up and then refining with a tuner, then leaving it alone and sticking to "normal" tuning methods.

 

[INTJ]

These two comments point to the reality of the matter. All just my own opinion....

There was no choice for an easy turnkey automatic system beyond the Prometheus until the AutoTrickler/AutoThrow FX120i was introduced.

The alternatives to get below the ChargeMaster were to close a loop on a balance using something like the Dandy vibration trickler using a tuned balance beam with transducers, or to close loop on an electronic scale. Folks have been hand trickling for decades and still can if they choose. That is just reality without even getting into the effects of a kernel.

The other reality, is that it isn't very difficult to show the improvement over a ChargeMaster in terms of the powder weight ES from a sampling, or to show it on the target at distance. The AT/AT FX120i is at least a factor of three more accurate and still faster than the CM even when you accept the occasional overthrow on the FX120i. Unless you are very disciplined and protect yourself from over/under throws and electronic drift, the CM is not a +/-0.1 grain machine. It can easily exceed an ES of 0.3 grains in a batch session.

In reality you are comparing a range of powder throws something like 0.07 grains, to 0.3 grains, not a single kernel.

Many shooters know how to tune for a forgiving node. Some of them are willing to run to their margins with a CM and shoot their game. Others choose not to surrender the safety margin or spare themselves the fatigue it takes to focus on the trickle doing large batches.

So, at the end of the day, it is more about keeping your tune safety margin than it is about a single kernel.

Like Alex says, the reality is the AT/AT FX120i is the only easy alternative to keeping tune margin but certainly not the only one. Once you step away from the tedious methods or the CM, for the same trouble you are at the plus minus kernel level if you guard for over throws.

So, like BHO said once about healthcare.... "If you like your charge method, you can keep your charge method.... YMMV

I take mine (V3 on A &D FX-120i) to the single kernel for my LR BR rifles. I do that by turning on the scale, then putting the cup on the platen, then zeroing. That way each time I pull the cup I can watch for drift. It slows me down a little but I typically don't have to load more than 75 rounds at a time.

When I do it the way most do (not checking pan weight for each charge), its is 2 kernel variation, or .03 to .04 grains. I tested all this and weighed the charges on my Sartorious Entris, which has .001 grain accuracy.

In practical terms, 1 kernel vs 2 kernels matters not. Unless perhaps we are loading N570 in a 6BR or smaller case.......

One thing I don't do is accept an overcharge or an undercharge--I correct those.

 

[Rockchuck]

I don't think 1 kernel make a difference at all. But the smaller the case the more accurate you need to be on your charges. I have been tinkering another. 22 long rifle loading and 1 tenth of a gr means alot. The common reloading scales are not accurate enough.

 

[Ccrider]

To the op, do you think that all of the short range benchrest shooters that threw powder all the way into the hall of fame were throwing to the accuracy of one kernel?

 

[Link]

Has anyone weighed the powder in there favorite factory round? How close are they?
Don

 

[Devin Wiggett]

Don't forget competitive shooting is as much a mental game as it is equipment.
Why not load to the kernel, if that makes you think you have done the best you can to enhance your performance that a good thing. Most people who argue the point probably have never shot a competitive match at distance. Every top national shooter I know measures the load to precise amounts on very expensive scales.
Proof is in the scores and awards hanging on the wall.

 

[Rsadams]

To me I don't care... It also depends on how well you can shoot the rifle....

 

[RegionRat]

Has anyone weighed the powder in there favorite factory round? How close are they?
Don

https://precisionrifleblog.com/2021/05/11/6-5cm-ammo-test-measured-round-to-round-consistency/

This was a multi part series of articles but the one I linked contains a set of data where they deconstructed a sample of a few of the factory ammo spread in the study. If you are interested, the other articles are linked.