Vertical Dispersion - Weighing Primers

[whatwind?]

Despite somewhat less than super precise weighing methods and showing results more precise than recorded, I still like the stuff in the attachment below because other factors or variables found in the loading process were eliminated. The primer blast waves were the only item measured and recorded.

https://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

Possibly, the group shapes or bullet holes are just vertically dispersed for reasons other than ammo characteristics - another variable.

conclusion...
With mass sorting on a sufficiently fine scale, the experiment to determine whether primer strength or uniformity has the bigger effect on muzzle velocity variations is simple: prepare a group of test samples with both unsorted andsorted primers and compare their standard deviations from the mean muzzle velocities. If one obtains the same result for numerousloads, then confidence builds that the result will likely be the same for other loads as well. In contrast, it is also possible that some loads are more sensitive to primer uniformity than others, in which case it might not benot possible to know whethermass sorting of primers will benefit a specific load until it is tried for that load.

 

[fyrewall]

I see your point actual velocity measuring and comparisons between weight sorted and just dumped out of the box with equal and reasonably uniform components and assembly

Why I like the attachment is that I have better things to do than weigh primers and run extensive velocity comparisons for my requirements. I am not a bench rest shooter and more than adequate results using primers having established high quality ratings is sufficient.

Would primers having uniform blast pressures be likely to produce uniform velocities?

Despite my causal approach to primer weight variations some of my extreme velocity spreads measure less than 15 fps. I think the actual group shape, like vertical spread, would be more important for long range results and that should also be considered

The attachment to me is a sensible way to determine primer quality bypassing variations introduced by the loading process.

 

[Joe Salt]

Look if you don't want to spend time Weighing them then don't. But you have a lot of time on your hands right now so go try it, you might like it.

Joe salt

 

[Alex Wheeler]

Its not as simple as velocity. Poor primer ignition will kill accuracy or cause fliers that wont show up in velocity. I know that from working on ignitions and fixing poor shooting rifles. Changes in the pressure curve may change exit time without changing speed. The only way to test for yourself is to shoot groups at the distance you will compete imo. If you just look for velocity changes you may not see the whole picture.

 

[dmoran]

The velocity variations between primers attribute to very small amounts of velocity in terms of the actual velocity, that is easily "lost in the noise" of the ammo's own standard deviations and the chronographs error factors. Sort to speak, if the ammo used has an SD of 5-fps and the chronograph has an error factor of 3-fps, for a total of 8-fps deviation error, the primers being tested would have to have more then 8-fps ES of variation to not get "lost in the noise". Ballistically, 8-fps can easily attribute to 3" of bullet path variation at 1000yds with popular calibers & bullet combinations that are commonly used at 1000yd competitions. Hence, why primer induced fliers are more easily seen on the target, then within the velocity data - IME.

 

[fyrewall]

Just trying to get a grasp on the stuff above.

I see it as velocity differences of 8 fps would be .26 percent around a velocities of 3100 fps but might cause 3 inches drop variations at 1000 yards (1.5 up & 1.5 down?). Would determination of .26 percent velocity differences require an inordinate amount of chronograph set up uniformity to achieve shot to shot consistency and lacking that uniformity velocity variations would be introduced?

Inconsistent primer ignition (poor primer ignition?) independent of total primer and explosive content weight but yielding closely equal velocities? Would primer pressure wave slopes vary causing bullet acceleration variations but equal muzzle velocities? Some time ago I measured 13 CCI 41 primers and found their average length to be .1217 inches, with a spread of .005 inches, SD = .0015 and using a 95% confidence level the primers would range from .123 max to .121 min for 1,000 population (df). Running the same routine for 50 samples yielded slightly closer max min results. My question now would these minute dimensional differences have an effect on accuracy that would not show up with measuring velocity differences.

 

[dmoran]

@fyrewall
Not wanting to open another can of worms ...lol, ... so not going to say one way or the other. But will say, besides weight qualification, I also measure my primers, sorting them into .0005" increments, and seat them to a measured depth/crush (K&M gauged primer tool #PGMOD2).

 

[fyrewall]

@fyrewall
Not wanting to open another can of worms ...lol, ... so not going to say one way or the other. But will say, besides weight qualification, I also measure my primers, sorting them into .0005" increments, and seat them to a measured depth/crush (K&M gauged primer tool #PGMOD2).

Good answer!

 

[Acyr]

Since I like many others have lots of free time on my hands I have been sorting everything. Brass, bullets and primers. Quite an eye opener for sure. I came across this guy today. One on right normal, left one double anvil. Wolf small rifle magnum. Do any of you think you would have spotted it without weighing it? How do you think it would have looked on paper at 1000 during a match. I am glad I won’t have to find out.

 

[memilanuk]

How do you think it would have looked on paper at 1000 during a match. I am glad I won’t have to find out.

Now that's one I think you should make a special mission to load normally, set aside in a zip-loc baggy with a note, and shoot it during unlimited sighters on a day with *really* good conditions - just to see what it really does.

 

[Acyr]

Now that's one I think you should make a special mission to load normally, set aside in a zip-loc baggy with a note, and shoot it during unlimited sighters on a day with *really* good conditions - just to see what it really does.

Monty that's a great idea! Once I get back to shooting I will follow up.

 

[Ned Ludd]

Now that's one I think you should make a special mission to load normally, set aside in a zip-loc baggy with a note, and shoot it during unlimited sighters on a day with *really* good conditions - just to see what it really does.

If the holes in the two anvils were aligned, I'd bet it would shoot normally. However, it looks like the two anvils are offset, with the one underneath covering up the holes in the one on top. potentially blocking or diminishing the primer brisance. Even though I like the idea of knowing how it works, I'm not sure it's such a great idea to test that one. You might end up with a round that won't fire, or even a squib. Not worth it, IMO.

 

[CharlieNC]

@fyrewall
Not wanting to open another can of worms ...lol, ... so not going to say one way or the other. But will say, besides weight qualification, I also measure my primers, sorting them into .0005" increments, and seat them to a measured depth/crush (K&M gauged primer tool #PGMOD2).

Donovan I wish I was as motivated as you to investigate so in depth. Guess I have too many other distractions! Stay well.

 

[dkhunt14]

No, but I may hit you up for some 215s lol.


Tom

What powder you gonna shoot in that 30? Matt

 

[dkhunt14]

conclusion...
With mass sorting on a sufficiently fine scale, the experiment to determine whether primer strength or uniformity has the bigger effect on muzzle velocity variations is simple: prepare a group of test samples with both unsorted andsorted primers and compare their standard deviations from the mean muzzle velocities. If one obtains the same result for numerousloads, then confidence builds that the result will likely be the same for other loads as well. In contrast, it is also possible that some loads are more sensitive to primer uniformity than others, in which case it might not benot possible to know whethermass sorting of primers will benefit a specific load until it is tried for that load.

The chronograph will not show it. Just like it doesn't show the best load. Matt

 

[dkhunt14]

View attachment 1166822 View attachment 1166823 View attachment 1166824 Since I like many others have lots of free time on my hands I have been sorting everything. Brass, bullets and primers. Quite an eye opener for sure. I came across this guy today. One on right normal, left one double anvil. Wolf small rifle magnum. Do any of you think you would have spotted it without weighing it? How do you think it would have looked on paper at 1000 during a match. I am glad I won’t have to find out.

I found one without an anvil. It was a Federal and from a lot that was super thick coated. Without the scale, I wouldn't found it. It was way lighter and I looked at it and don't see it right away because of the thick coating. If that primer was in my record rounds, my whole season would of been over. Matt

 

[tom]

What powder you gonna shoot in that 30? Matt

I've shot 4350 and 16 so far, but only with 210fed and br2 so far. I like the 215s in my 338s though. With no matches going on, I will probably play with some 4831 and similar in my 300 as well

Tom

 

[dkhunt14]

I've shot 4350 and 16 so far, but only with 210fed and br2 so far. I like the 215s in my 338s though. With no matches going on, I will probably play with some 4831 and similar in my 300 as well

Tom

In most my testing with a WSM, the 210 primer was better then a 215. I know you have a little less capacity then the WSM so it might even be better. But I shoot H4350 and a 210 bullet. I believe H4350 and the weight of the load doesn't need a magnum primer. It's not that much more powder then a 30-06. Maybe the RELOADER powders or something slower then H4350 woukd like the magnum primers. Matt

 

[INTJ]

With both 300 WSM LR BR rifles I have had, one from a dozen years ago and one right now; Fed 210s have easily produced single digit ES with H4831SC and now with RL-23. Groups on paper look good too and I have never had any issues whether shooting at 30 degrees or 100.

 

[Dave Way]

For those who may doubt a primer adds much energy to the to the loaded round, here is a photo I took. 205M (primer only) in a 6.5x47 case. Barrel on that rifle was 25.5” long with the brake removed. In addition to energy I would have to assume the primer ignition also affects barrel vibration as it begins the ignition process. Like Tom, I have verified a direct relationship between primer weight and compound weight.

http://forum.accurateshooter.com/threads/weight-sorting-primers-test.3966861/



I sort primers,
Dave.