Vertical Dispersion - Weighing Primers

[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.

 

[dkhunt14]

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/

View attachment 1167018

I sort primers,
Dave.

I believe you are into the reason why it matters. It's not the velocity but the ignitial blast or shock. Maybe it changes the way the barrel vibrates. Matt

 

[tom]

I believe you are into the reason why it matters. It's not the velocity but the ignitial blast or shock. Maybe it changes the way the barrel vibrates. Matt

I think it almost has to (opinion of course), because I have 3 6mm's tuned right now. They're shooting smaller than anything I've ever seen before on a consistent basis, at my testing range that I've tuned several record barrels on, and all 3 chose different brand/type primers. One will always give me the "ladder shape" I'm after, more so than the others. I won't begin to venture a guess at why, I just roll with whatever the paper is telling me.

Tom

 

[Nature Boy]

I found one without an anvil.

I found this in a new pack of pistol primers

looks like it was fired

But it had no primer compound in it. I’m still scratching my head over this one

 

[fyrewall]

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

I believe you are into the reason why it matters. It's not the velocity but the ignitial blast or shock. Maybe it changes the way the barrel vibrates. Matt

Fig. 2 of the attachment shows blast pressure wave forms, possibly this would affect barrel vibes, generation rates of chamber pressure, and accuracy.

The attachment does not condemn velocity measurements in fact it suggests comparing velocity SD's from mean sample velocities to build load confidence. Chronographs are way cheaper than pressure transducers. The attachment did mention, "numerous loads" Super accurate scales are also expensive.

I visually inspect every primer I use with a 10X magnifier (does not take that much time - line them up and look at each one). I have never (not yet) found an empty primer or double anvil(S). But I have found some with uncentered or tipped anvils. Reading about primers tells me that the anvils have a somewhat flattened top which is intended to increase the firing pin strike area.

Seating that double anvil primer would squash the insides and all sorts of bad stuff could happen.

 

[JFrank]

A good question, and one I asked myself. I do it to ensure that each primer is seated to a precise depth.
Will link you to the tool we use and it's description: https://kmshooting.com/product/primer-gauge/


------------------------------------------------------------------------------------------------------------------------

Some try to shoot extremely small and precise on every target, and do just that almost every time they shoot a match. When I see your winning results and aggregates, I will pay more attention to your inputs and advises. Until such a time, I will continue paying most attention to the inputs, advises, and methods used by those that are winning. Myself will continue testing as many aspects that I can, and put in the due diligence to every probable effecting aspect that I choose to test and/or utilize.

------------------------------------------------------------------------------------------------------------------------

Well I haven’t won and really don’t expect to,considering the level of competitors at DC I may never win and that’s fine as well. I did manage to reduce my aggs by 3 in over the last 6 targets so that’s an improvement I look to build on.
Nice to visit with you last June at the range and hope all is well.
Jim