A while back I performed a test using 175 gr Nosler CC BTHPs, Varget, FC 308 brass, and Wolf LR primers. I loaded 44.0 to 45.2 in increments of 0.2 grains. I plotted impacts at 316 yards which was the maximum distance of the range.

There was a node at 44.2 grains.

Yesterday, I tested that load shooting groups at 100 yards while helping a buddy break in a barrel.

Here were my results with various types of brass:
Brass, Average Velocity, SD
FC15 2,631 14
FC 308 2,651 9
Lapua 2,650 17
LC 14 2,646 11
LC LR 2,657 8
PPU 2,652 9
RP 2,643 6
Winchester 2,607 12
WRA 2,628 6

Some of this was surprising. Winchester having the lowest velocity was expected.

The Lapua was unsized but chamfered. All groups except FC 15 were MOA or less.  FC 15 likely should have been better. I had too much glare on my scope’s front lens.  Velocities were recorded with a Labradar.



Brass results

This week, I’ll test velocities with an assortment of primers.

Use Imgur.com

Primer groups

I shot the load again varying primers.

Primer Velocity SD
CCI 200 2,648 14
CCI 34 2,675 32
CCI BR2 2,646 22
Winchester LR 2,660 17
Fed 210 2,656 single digit SD but labradar didn't register all the shots

Primer selection definitely affects consistency of velocities.

Originally Posted By AR-180:


"I shot the load again varying primers.

Primer Velocity SD
CCI 200 2,648 14
CCI 34 2,675 32
CCI BR2 2,646 22
Winchester LR 2,660 17
Fed 210 2,656 single digit SD but labradar didn't register all the shots

Primer selection definitely affects consistency of velocities."

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Your testing has glaring deficiencies

#1 You ought weigh the empty once fire cases first.  Then you should weigh the fired brass with a spent primer to see how many grains of water they hold.  This will show the Winchester has the most case capacity and hence more room for the powder burning to expand so to speak. The less capacity builds pressure sooner.
#2 Accuracy is KING not velocity with measured with ES and SD.
#3 Your Varget Powder charge is way over the line for most brass except Winchester. Consult a Sierra 5th edition for Varget data and Federal brass, the 6th edition uses Winchester Brass as does Hodgdon online data.
#4 You need factual foundation to draw conclusions.  Like work up a load with CCI 200 and Compare to CCI BR-2 Primer and CCI #34 primers

http://optimalchargeweight.embarqspace.com/ocw-test-example/4529811475

My test was set up for a load that works in my rifle. The theory of ocw is that it accounts for small differences in components. Well, how small is small?  Primer type could not be substituted as well as brass type for my load. This test helped me see how an ocw load responds to differences in components.

The data listed in reloading manuals is a guide. It generally lists a very specific set of components and a single firearm’s action or worse, a universal receiver.

I don’t know anyone doing the bulk of their shooting with a universal receiver. Therefore, these data aren’t useful for drawing direct conclusions.

Sierra tests their 155 grain Palma bullet at 2.775” and lists less than 45 grains of Varget as a max. I don’t know a single Palma shooter using such a short length or so little powder.

My rifle likes 46-47 grains depending on the throat of the barrel. For most competitive shooters, reloading manual data are a starting point and virtually never an ending point.

Yes accuracy is important, but the ES and SD are telling a story. If you have 2 loads that are accurate, one with single digit SD and Low ES, and that data holds up, that will make for more consistent shooting at distance. That velocity spread will become a Vertical spread at 1000 yards. So for example I shoot a 1/4 inch group at 100 yards with a 40SD and a 3/8 inch group with a single digit SD, I am going to test again. If this data holds I am loading that single digit load all day.

Hey, you're a Palma shooter in NC?  Do we know each other?

The nuances that are caused by changing components aren't properly recognized until you have about 20 samples at a bare minimum.  Even that data is subject to be off enough that I wouldn't compare it to other data with confidence.

For example, I recently tested .223 bolt gun loads with Fed 205, CCI 400, and CCI BR4 primers, keeping everything else the same and shooting 35 shots of each.  Velocity averages varied slightly but SD and ES were negligibly different.  What is cool, however, is to watch various tests progress with a "running" average and SD plotted in Excel.  You see a TON of noise up to about 25-30 samples, then everything starts to level out-- much slower movement.

It's not what anyone wants to hear, but if I pluck any of the sampling I've done at 5 shots, the results are ENTIRELY inconclusive as to what the final result will be at 35+ shots.