The road to 1,000 yards and beyond

Hatcher's Armory
#1

So, as I have posted before, I’ve built a 1,000 yard rifle, and have been actively working on load development for it. to shoot at 1,000+, you need a rifle/load combo with extremely tight intrinsic accuracy.

Using Blank Hills match ammo, I am consistently able to shoot .35" groups with this gun all day long. But after 2 separate ladder tests, my handloads could not produce better than .65" groups. This forced me into examining my precision loading routine and tools. Handloads, properly done, should always beat factory loads.

After a really critical look at my routine and tools, I could find nothing out of order. Case prep looked spot on (turned necks etc). I was weighing every charge, Seating depth duplicated the BH ammo. I could see a node at the 43.0g-43.1g mark, but my chronograph was listing extreme spreads and standard deviation values that were just too high to produce a really small group.

Hmm.

I settled on the charge as the culprit, since all other variables seemed excluded. After a great deal of reading, I learned that most electronic powder scales use a strain gauge as the measuring element, and that strain gauges were accurate to only 1/10 of a grain (4-8 kernels of Varget, in this case). LR competitors reported that this wasn’t accurate enough - you needed to weight to individual kernels of powder. Balance scales generally are accurate to less, as a result of wide lines and reading errors, along with unclean knife-edges. They also take a long time to weigh with.

I’ve been using a Hornady Lock-n-Load powder dispenser. Accurate to .1g, but internet anecdotes report it to be closer to .2g with stick powder.

So, I determined that I needed a scale accurate to within .001G ( 0.0154 grain). Jewelers scales are often this accurate. So I found a Gempro 2 -300 scale on sale for $165 (http://myweigh.com/product/gempro-2-300/), and ordered it. It arrived today. So next step, another mini ladder test, focused around the node at 43.0 grains of Varget. I’ll post results later for the (admittedly few) people interested in this.

So I guess you can take away from this that not all measurement systems produce precise and accurate results. LR ammo requires a lot from the reloader. I guess I’ll save the LNL for hunting ammo and pistol stuff. Mostly, for loading Tapper’s Premium 6.8SPC II HD (Hog Disassembler) rounds.

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#2

You might be looking at only half the variability of your scales. My scales are rated as a +/- .1 grain. So that means your variability could be .2 grains from load to load with the same reading on the scale.

Also, are you using the auto load dispenser with the digital scale or a standard manual powder measure with the lever on the side? Both can be accurate, but the manual lever operated one has to be done the same every time to get charges that are consistent load to load, though it still wouldn’t be my choice.

Last, Are you sure the variability isn’t you or the conditions rather than the load. The .35 group may have been a fluke, rather than the standard your gun always shoots. What range are you basing these groups on? Did you shoot the ammo on the same day in the same conditions?

I’ve found it easy to call myself an expert marksman when I had @Gimli standing over me pointing out all my mistakes and coaching me to tighter and tighter groups. Only to then go out on my own and see how bad I can shoot when not coached.

#3

That’s correct, but it’s probably more accurate to say that the error will produce a distribution of values centered on the mean (selected value), with deviation of (something I’m too lazy to calculate). But you are correct that the absolute deviation is .2 grains. However, bear in mind, that the listed error of .1g means “from the selected charge weight”, so you should never really get more than a .1 error, over or under, for any single round. In a group of rounds, the error spread can be as much as .2g.

The LNL uses an electronic scale. I have used Harrell’s Culver powder measures with good success for many years, but regard other measures as not accurate enough for the reloading I prefer to do. But even the Harrells are not precise enough to play group size games at 1,000yds. They are a worthwhile consideration however, and many benchrest shooters swear volumetric charging produces smaller dispersions than weighed charges (usually due to moisture absorption rates in powder - in other words a kernel on the edge of a charge will weigh more than a kernel in the middle protected a bit from humidity).

As to the rest - been shooting competitively a very long time. My technique is relatively good at the bench.

#4

Well, whatever the deviation is, I am sure it is standard.

#5

Do you have several calibrated weights to use as a reference standard when you start? Ideally 3, one near normal weight and ones near your upper and lower limits.

With calibrated references you can always check the scale before use.

#6

This would solve most of those little issues:

3E5CB337-2C52-4E0F-BBA0-E4367C6CB509
3E5CB337-2C52-4E0F-BBA0-E4367C6CB509.jpeg960×562 32.1 KB

Sorry …:sunglasses:

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#7

Are you leaving your ammo in the sunlight? Or are you waiting keeping a round in the chamber too long to where the ammo it getting warm that way? Leaving the ammo to get hot in the car? Recent changes to the Barrel at all that could change the barrel harmonics?..

Those are a few that come to my mind.

Additionally I hear the Hornady electronic tends to drift. (Not personal experience)

You can get a better beam scale, RCBS has/had them around that go beyond .1 grain. I haven’t seen one for a while but its not the standard 505.

Here is another electronic… you better be sitting down almost 1,000$
https://balance.balances.com/scales/569

#8

What are you using for projectiles?

#9

Yes, I have 3 SEK-2 calibration weights.

No, shooting from shelter, car air conditioned. I haven’t really noticed much drift from the hornady, but it is listed as accurate to .1g and various inet users have said even that was generous.

RCBS has the 10-10 scale, which has large enough balance to get to .001g accuracy, but it requires a few mods to get you there.

175g Sierra Matchkings, same as the Black hills load.

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#10

So I’m confused as to your bench mark of .35 inch group. Is this an average grouping of multiple sessions/targets or just the best grouping you managed to shoot ever with the box rounds? I ask because target shooting is often a mix or science and art. 1 data point is not great for the scientific approach.

Second, are the sierra match king bullets you are using in the hand loads the same bullets that were in the box ammo you purchased? Same question with the powder being used in the hand loads same type and charge?

All of this gets back to fully defining your bench mark before trying to beat it/

#11

This is a reference to my initial group tests with the rifle, using 6 3-shot groups with Black Hills Match, where the max size was .501", and the min size was .30". The average was about .35".

Federal Premium Match produced an average of .77" with the same gun, on the same day.

I normally clean and cool after every 20 rounds, and cool 5 min between strings.

I’m loading up for a second ladder test with the new scale now, hope to shoot it this weekend, so we’ll see if my theory holds water.

Sierra doesn’t produce 2 types of 175g MKs. Black hills told me they were MKs, but wouldn’t share the powder type, which I believe to be RL 15 based on its looks. The Varget I’m using is a stick powder used by most LR .308 shooters, and known to be excellent in this loading. I’m not really looking to duplicate the BH ammo, I want to better it. It’s the erratic results (high ES and Sd) that have me looking for problems.

#12

Back in my grandfathers target shooting days he modded a balance beam by soldering a 2" flag to the bottom of the beam. The flag sat in a little jar of oil and provided some dampening resistance to the beam. Not sure it’s any more accurate than today’s electronics, but it’s still dependable… and slow.

Old tyme trick for the day.

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#13

One issue with some electronic scales, at least as of a few years ago, is that often, the software expected changes in load to be in sizable chunks. Put your pork chop on, take it off, measure out seasoning in large enough increments to be tasteable. But below a certain increment, they presume that the change is a drift in the strain gauge due to temperature or other environmental factors, and subtract the tiny delta back out. Obviously this can be an issue with trickling powder. It might not hurt to double weigh some charges after slow trickling, and see if after repeating the zero, and bringing the charge back in one add, if you are getting appropriate results.

#14

Just as an update, I did a little testing with the Gempro scale.

To do this, I first plugged them both in, and fired them up. I allowed them to run for an hour, stabilized the temperature to 72F, turned off all fans and AC. I adjusted the Hornady scales operating parameters according to Hornady’s recommendations for the type of powder i was using (Varget). I also left the “straw trick” in place, since it was there when I shot the last ladder test.

I then calibrated both scales and allowed them to sit for an hour and get fully temperature stabilized. And calibrated them again.

I then tared the Gempro with the powder cup from the Hornady, and started throwing 43.0 grain charges on the LnL dispenser, then weighed them on the Gempro. Every five charges, I verified the scales with the checkweights.

After 20 iterations, I got the following:

Minimum Charge thrown: 42.92gn (6 times)
Max Charge thrown: 43.08 (once)

Average: 42.98gn

Extreme Spread (ES): 0.16 grains

Standard Deviation: 0.06

Consider that, in relation to the velocity values seen:

image
image.png886×389 7.73 KB

This result also matches what I saw in the rifle - vertically opened groups, with very little horizontal dispersion.

The next test, will be a more intense ladder around that 43.0gn mark that looked like a node, using charges weighed on the Gempro. Guess I need to go to the range soon. How awful.

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#15

Any day at the range is a good day.

#16

What is the OAL of the cartridges you’re making vs. the factory rounds? Those speeds are too far off to look like that little amount of powder is the problem.

If they are longer than the factory rounds, measure it, chamber it, and measure it after you pull it.

#17

These were seated .015 off the lands (from ogive).

When you consider tthat in this pressure region, it looks like 0.10gn is worth about 30-40fps, its a reasonable theory that charge weights variance is the sourceof the issue, but perhaps not the only source, or even the source this time. But so far, its the only thing I can see to chase.

#18

I don’t recall, Did you check the volume of the cases, then match them?

#19

I sorted them by weight, but as is usual with Lapua bras, only a few culls. Their dimensions are remarkably consistent.