CCI Primer weights.

[Chubbs]

Hi Guys
I thought I would weigh some primers to see what the spread would be. I weighed them on a A&D FX 120i in grams. I don't know how much the difference there would be between the cups and anvils. In other posts I have read they are pretty consistent with their weights. If (Big IF) we just say it's down to the filling then you could possibly see where a flyer could come from. I know there are other factors such as case volume, bullet and powder. The difference between the lightest and heaviest was a bit of a surprise. To the naked eye the anvil did seem to be sitting further out from the cup on the heaviest.
It was a tedious chore and not one I wish to repeat. I certainly don't measure case volume but can't help but wonder if the smallest case capacity was paired with the heaviest primer what would the outcome be at 1000+ yards.

1 GRAM = 15.4324 GRAINS

CCI 200
0.323GMS – 0.344GMS
SPREAD OF 0.021GRMS / 0.324 GRNS

CCI 250 MAGNUM
0.329 GMS – 0.343 GMS
SPREAD OF 0.014 GMS / 0.216 GRNS

 

[Rocketvapor]

Measuring primers with a milligram scale is cutting it close.
These are SRP, CCI 450.


Try some light vs heavy at several hundred yards. Won't make a hill of beans at 100yds.

 

[Ranger188]

And then weigh the empty anvil to see if it was more primer mixture
or it was more metal.
Then see if the ones with the heavier primer mixture made a difference.

 

[Rocketvapor]

From a test I did on CCI450 using AND EJ-54D2 for weight and Garmin for velocity.
Posted a thread somewhere.
Shot round robin, 1 heavy, 1 light.
values are
Primer weight, as fired weight, weight loss, muzzle velocity.
1 -- 3.765, 3.400, 0.365, 3036.8
30 - 3.625, 3.375, 0.250, 2989.2
2 -- 3.760, 3.390, 0.370, 3042.7
29 - 3.625, 3.360, 0.265, 2989.0
3 -- 3.765, 3.385, 0.380, 3054.4
28 - 3.620, 3.360, 0.260, 2987.4
4 -- 3.775, 3.405, 0.370, 3058.4
27 - 3.615, 3.370, 0.245, 2993.1
5 -- 3.755, 3.395, 0.360, 3050.2
26 - 3.610, 3.360, 0.250, 2977.4
6 -- 3.755, 3.395, 0.360, 3046.2
25 - 3.630, 3.380, 0.250, 2996.3
7 -- 3.750, 3.395, 0.355, 3037.8
24 - 3.630, 3.370, 0.260, 2982.8
8 -- 3.750, 3.385, 0.365, 3047.0
23 - 3.630, 3.370, 0.260, 2992.5
9 -- 3.750, 3.390, 0.360, 3055.4
22 - 3.635, 3.370, 0.265, 2987.9
10 -- 3.750, 3.390, 0.360, 3029.2
21 - 3.635, 3.365, 0.270, 3021.1
11 -- 3.740, 3.380, 0.360, 3055.1
20 - 3.635, 3.360, 0.275, 3010.1
12 -- 3.730, 3.385, 0.345, 3053.5
19 - 3.630, 3.360, 0.270, 3010.3
13 -- 3.730, 3.380, 0.350, 3063.0
18 - 3.635, 3.360, 0.275, 3013.2
14 -- 3.730, 3.380, 0.350, 3032.3
17 - 3.635, 3.370, 0.265, 3003.1
15 -- 3.730, 3.385, 0.345, 3044.6
16 - 3.640, 3.375, 0.265 2999.9
Range of primers: 0.165 grains
Range as fired: 0.045 grains
Range of weight loss: 0.135 grains
Extreme Spread of Garmin Xero muzzle velocities 85.6 fps.


In both pics below (two different tests on different days @ 600yds) heavy hit high, light hit low.
In this pic, 9 is off to the left, 10 is high in the 9 ring.


"9" is behind "10"

Believe the scale or let the target talk to you.

 

[Straightshooter1]

From a test I did on CCI450 using AND EJ-54D2 for weight and Garmin for velocity.
Posted a thread somewhere.
Shot round robin, 1 heavy, 1 light.
values are
Primer weight, as fired weight, weight loss, muzzle velocity.
1 -- 3.765, 3.400, 0.365, 3036.8
30 - 3.625, 3.375, 0.250, 2989.2
2 -- 3.760, 3.390, 0.370, 3042.7
29 - 3.625, 3.360, 0.265, 2989.0
3 -- 3.765, 3.385, 0.380, 3054.4
28 - 3.620, 3.360, 0.260, 2987.4
4 -- 3.775, 3.405, 0.370, 3058.4
27 - 3.615, 3.370, 0.245, 2993.1
5 -- 3.755, 3.395, 0.360, 3050.2
26 - 3.610, 3.360, 0.250, 2977.4
6 -- 3.755, 3.395, 0.360, 3046.2
25 - 3.630, 3.380, 0.250, 2996.3
7 -- 3.750, 3.395, 0.355, 3037.8
24 - 3.630, 3.370, 0.260, 2982.8
8 -- 3.750, 3.385, 0.365, 3047.0
23 - 3.630, 3.370, 0.260, 2992.5
9 -- 3.750, 3.390, 0.360, 3055.4
22 - 3.635, 3.370, 0.265, 2987.9
10 -- 3.750, 3.390, 0.360, 3029.2
21 - 3.635, 3.365, 0.270, 3021.1
11 -- 3.740, 3.380, 0.360, 3055.1
20 - 3.635, 3.360, 0.275, 3010.1
12 -- 3.730, 3.385, 0.345, 3053.5
19 - 3.630, 3.360, 0.270, 3010.3
13 -- 3.730, 3.380, 0.350, 3063.0
18 - 3.635, 3.360, 0.275, 3013.2
14 -- 3.730, 3.380, 0.350, 3032.3
17 - 3.635, 3.370, 0.265, 3003.1
15 -- 3.730, 3.385, 0.345, 3044.6
16 - 3.640, 3.375, 0.265 2999.9
Range of primers: 0.165 grains
Range as fired: 0.045 grains
Range of weight loss: 0.135 grains
Extreme Spread of Garmin Xero muzzle velocities 85.6 fps.


In both pics below (two different tests on different days @ 600yds) heavy hit high, light hit low.
In this pic, 9 is off to the left, 10 is high in the 9 ring.
View attachment 1579597

"9" is behind "10"
View attachment 1579600
Believe the scale or let the target talk to you.

I put your numbers in a spreadsheet and sorted by the "Weight" you listed and the second sorted "as fired weight". Here's what that looks like:

 

[Rocketvapor]

Pretty easy to see sorted.
If you look close there is some overlap in velocities caused by Cup/Anvil weight.
Looks like 1/4 of the weight variance can be metal and not primer compound.

 

[Doom]

Looking at @Rocketvapor's data it is not surprising that there is very good correlation (R^2=0.87) between the weight loss on firing and velocity since it represents an increase in energy input and would be expected to show up in velocity. There is very little correlation between the total weight of the primer (R^2=0.27) and a somewhat greater correlation (R^2=0.56) between the fired weight and velocity.

To make any firm conclusion would require that additional test be looked at but based on this test it doesn't appear that weighing primers is going to produce the intended results.

 

[Rocketvapor]

No more tests from me
I did 10 shots on target, 10 more on target, and a 30 round Round Robin for velocity.
All out of culls for now.
Someone else can test their culls.

 

[RegionRat]

Looking at @Rocketvapor's data it is not surprising that there is very good correlation (R^2=0.87) between the weight loss on firing and velocity since it represents an increase in energy input and would be expected to show up in velocity. There is very little correlation between the total weight of the primer (R^2=0.27) and a somewhat greater correlation (R^2=0.56) between the fired weight and velocity.

To make any firm conclusion would require that additional test be looked at but based on this test it doesn't appear that weighing primers is going to produce the intended results.

Doom, not sure how you got R^2=0.27 on the sort by weight of primer versus velocity?
I plotted the data and included the regression. R^2=0.8382
Looks like a pretty clear cut case to sort by weight.

 

[Straightshooter1]

No more tests from me
I did 10 shots on target, 10 more on target, and a 30 round Round Robin for velocity.
All out of culls for now.
Someone else can test their culls.

Very likely, I'll be doing this. But not until it cools down some around here (Arizona).

 

[RegionRat]

And since folks asked... and one says he will ply me with Macallan 18...
Here is the primer weight loss versus velocity.



ETA: On average, the slope indicates the velocity change per grain difference in primer compound. So the k = 538.81 fps per grain of primer compound. But, since we can't measure the primer loss till after the fact, we look at the above graph and see the slope k= 434.74 fps/total grain, so still a significant value.

 

[Rocketvapor]

Seems I've seen those before

 

[RegionRat]

Okay, so in Rocketvapor's example, not sorting would cost him the potential of 50 fps added to the ES to put it in simple terms.
To get the picture, the batch on the left will run roughly 2995 and the batch on the right will be roughly 3050 on average.
That isn't a huge difference at say 600 yards, but it does start to show when the rifle shoots tight and he is on his game. Now ask yourself if you want that extra 50 fps in your ES at 1000 when a simple scale sort will remove it? YMMV Carry on.

 

[Fire Dog]

Very likely, I'll be doing this. But not until it cools down some around here (Arizona).

Monsoon rains now so should be getting cooler but of course the humidity is up…

 

[RegionRat]

Monsoon rains now so should be getting cooler but of course the humidity is up…

Darn. Two good water years in the SW and we finally have the doves and quail, and now the Monsoons will flush them south.....

 

[Fire Dog]

Darn. Two good water years in the SW and we finally have the doves and quail, and now the Monsoons will flush them south.....

They will be welcome in Southern Az…. Plenty of fresh feed coming up now…{:~)

 

[Straightshooter1]

Monsoon rains now so should be getting cooler but of course the humidity is up…

Yes, the monsoon rains cools things down quickly and humidity rises quickly . . . it often moves through, heats up and drys out within hours and we're back to HOT!

 

[Doom]

Doom, not sure how you got R^2=0.27 on the sort by weight of primer versus velocity?
I plotted the data and included the regression. R^2=0.8382
Looks like a pretty clear cut case to sort by weight.

View attachment 1579938

Not sure what happened when I translated/imported the data but it didn't get all the initial weight correct on all the points. I'm slightly different than you but close enough.

 

[Rocketvapor]

This tells me what is going on with primer mix and cup/anvil weight.
Granted there is likely a range of crud left in the cups, and Cup/Anvil weights and Mix weights (loss) overlap some.
Range of primers: 0.165 grains
Range as fired: 0.045 grains
Range of weight loss: 0.135 grains
Extreme Spread of Garmin Xero muzzle velocities 85.6 fps.

 

[Area51]

How is heating and cooling, continual fouling of the bbl vs friction taken into account?
Bullet uniformity, weight and ogive sorted?
Obviously the same brass for test lotts.
This is an interesting and informative thread with some decent science, needs more confirmation and test validation of the other variables.
Good thread.
Acid