Primer Weight

[Fuj]

For both Dave and Tom......You both are long range shooters, so let
me ask this......How large of a charge are you loading and it's burn
rate area ?? I mainly shoot short the last few years with cartridges
that load below 35 grains of powder, and powders that are faster
then Varget.....What I'm getting at is; A primer sort is more conclusive
with a much smaller BR cartridge then it would be with something
used in the LR game. Quite honestly, were talking a good average of
a 20 grain charge of more powder, of which it is a much slower powder.
I would offer my conclusion that there is a point that the value of the
sort would get meaningless as the charges increase with slower burning
powders......

 

[RegionRat]

I would offer my conclusion that there is a point that the value of the
sort would get meaningless as the charges increase with slower burning
powders......

Agree, but a little different view is...

What is the expectation for primer weight stats as a stand alone issue?
What are the potential effects in terms of the internal ballistics and the contribution to the total charge?
How does a loader learn to set the tolerance limits on their primers (bullets, brass, powders, girlfriends, etc.)?

Threads like this tend to go into swirl due to false positive and false negatives, and reports that are not put into context. In other words, some folks could never tell you the difference because their capability is too poor, and others are just testing good batches.

The vast majority of primers shipped are not escapes or rejects, thankfully. However...

Primers from all makes and models have had quality control escapes over the decades with a range from marginal performance to very poor performance and even duds. Some have experienced leaks and dimensional issues. It is rare, but certainly not zero.

There is no point to the mob scene of folks who keep reporting there is no issue when they are testing only good primers (bullets, brass, etc.). That isn't as productive as a report of the level of primer weight that does matter and in what context it was tested. Which is the point that Fuj is trying to make.

A 5 grain difference in a 223 case is one thing, a 5 grain difference in a 300 WM is another, and so it runs down the line.

The mob is in denial, It is understandable because there is a cost associated with the work it takes to sample screen or complete sort.

I don't give much advice unless I see us heading into a brick wall.... Rookies should learn how to sample test all their components and learn when they have no worry as well as when those results show the potential for a reject failure. Weight on bullets, brass, primers, powder, etc., is easy because we have good instruments. The hard part is arriving on what those weights and stats tell us.... At the start of a reloader's journey, there are more important basic issues to master. It isn't long before they learn the importance of batch management and setting their own quality controls. YMMV
Carry on.

 

[tom]

For both Dave and Tom......You both are long range shooters, so let
me ask this......How large of a charge are you loading and it's burn
rate area ?? I mainly shoot short the last few years with cartridges
that load below 35 grains of powder, and powders that are faster
then Varget.....What I'm getting at is; A primer sort is more conclusive
with a much smaller BR cartridge then it would be with something
used in the LR game. Quite honestly, were talking a good average of
a 20 grain charge of more powder, of which it is a much slower powder.
I would offer my conclusion that there is a point that the value of the
sort would get meaningless as the charges increase with slower burning
powders......

31ish 4895 in my 6s, one barrel a grain less. 60-63 4350 in my wsm for me.

Tom

 

[Evan]

For both Dave and Tom......You both are long range shooters, so let
me ask this......How large of a charge are you loading and it's burn
rate area ?? I mainly shoot short the last few years with cartridges
that load below 35 grains of powder, and powders that are faster
then Varget.....What I'm getting at is; A primer sort is more conclusive
with a much smaller BR cartridge then it would be with something
used in the LR game. Quite honestly, were talking a good average of
a 20 grain charge of more powder, of which it is a much slower powder.
I would offer my conclusion that there is a point that the value of the
sort would get meaningless as the charges increase with slower burning
powders......

I know you didn't ask me, but I’ve tested with a 22BR (28gns Varget or 32gns H4350) and a 6.5x47 (40gns of RL16). 6.5x47 I thought showed less vertical when I kept primers the same within 0.02gns although I didn’t really quantify that at the time. The 22BR shows no discernible change.

I think it’s a complex relationship with the sensitivity of your tune where a forgiving tune may not wander out of shooting well from primer variations alone whereas a peaky narrow tune might easily get knocked out by primer variations. I am conveniently ignoring the elimination of outliers in the sorting and just talking about the variation that is within the normal distribution of weights. Outliers in any population should be set aside, but sorting for outliers is faster and much less taxing then binning all your primers (what is the correct bin size?)

 

[Fuj]

I think it’s a complex relationship with the sensitivity of your tune where a forgiving tune may not wander out of shooting well from primer variations alone whereas a peaky narrow tune might easily get knocked out by primer variations.

Well put, and noted.

 

[dkhunt14]

When I've set out to test something like this I've not tried nor expected there to be a difference in group size heavy vs light. I've always looked for a poi change, at distance, when firing round robin (alternating shots in this case). Even then a condition can catch your first and/or last shot, but the groups centers either are or are not in the same location. It goes without saying you're gonna want a gun that's good enough, tuned well enough, to see the difference if there is one.

Tom

I believe in this. The rifle needs to shoot good enough to see any difference. Also the weight differences these guys are saying is alot smaller then what I have seen. Matt

 

[Sumtoc]

Guys, thanks again for all the great feedback. I know it takes time and effort to weight sort primers. I also strongly suspect that I don't shoot well enough or test large enough batches to see any real difference. (With my current brands/lots.) So my testing seems pretty meaningless. Knowing that some of you guys don't have these handicaps is huge, your input is highly valued.

I personally think that checking for and identifying the outliers is worthwhile. Sort of testing lots for consistency. But for LRP/284 what constitutes an outlier? I also shoot 223 in FTR at 600, what about SRP?

 

[Larry Koch]

Me think there are so many factors that need to be taken into account when shooting small.
On primers it would seem to use a quaility primer that works well with your load. Once established a load. Then I test many different primers thanks (Joe). You will come to find the same one or brand keeps doing the best on your target. Like I said try not to get tunnel vision on one item. You have the gun, the ammo, and you. What can you do for your personal self to improve your shooting???????

 

[Rsadams]

It's a free country for right now so do as you wish... I am not going to take the time to weigh primers... If I miss because of that it's on me I guess I would rather be shooting... I have seen people shooting a thousand with factory Hornady ammo and I promise you they are not weighing anything but powder charge and it's not even within a tenth....

 

[memilanuk]

Yes, but are those people the ones you're competing against?

If they are, then I doubt you're in a shooting discipline where any of this matters. We're not talking 'banging steel' here.

 

[RegionRat]

But for LRP/284 what constitutes an outlier? I also shoot 223 in FTR at 600, what about SRP?

Without a sample of at least 30 primers from a batch, it isn't easy to identify. Without getting into math class or a debate on what an acceptable average and SD is for a brick or batch of primers, I will show a notional normal distribution and an outlier is considered a bad sign. Ones that are more than 3xSD away from the average weight, hi or low, should be pulled out and kept for special testing.


So it is an easy matter to apply this concept to anything else too. With your scale, you can just pull a random sample of at least 30 and weigh them. It is optional to bin them at this point, but you do need to record each one and serialize it so you can double check after the math.

If you see a nice distribution, it is your choice to just go on your merry way, or weight sort and test the -3Sigma set against the +3Sigma set.

You won't have that pretty graph in front of you, so you just watch for ones that are beyond 3Sigma above or below the average and then decide.

If you keep track over the years and batches, it isn't a good sign to see the average batch weight change by more than 1 Sigma, or to see even a few out of a random sample pop out more than 3 Sigma away.

The vast majority of baches will not contain outliers. But it becomes a matter of your own risk to decide if the size of the two tails of a normal distribution will meet your needs or need to be sorted. YMMV

 

[tom]

Wish they didn't stack them on end, but a careful inspection never hurts either

Tom

 

[Evan]

@RegionRat wrote out the more detailed response context for my “ How do we bin them” question. +\- 3 sigma is a much easier sort, since in my experience that would be looking for about 0.1gn away from the average which could e established with even less than the statistically significant 30 that RegionRat suggested. That is less attentive work than reliably sorting them into bins defined by the weight resolution limits of your scale.

 

[quest450]

my head is spinning after reading last few posts ( not tom's post )
I didn't know you had to be a rocket surgeon to sort primers
Sigmamya$$ just set your A&D 120 to grams and go to town, sort them by 0.001 gram and you're g2g

 

[RegionRat]

Most cheap calculators will have an Average and Standard Deviation (sigma) on there and we have taught uneducated third world peasants to run QC samples.

It really isn't hard, our schools just suck.

 

[quest450]

 

[RegionRat]

I saw a gal who knew how to run an abacus once. It was eye watering.

She was probably in her 90's at the time, and this was back in the late 70's so I am sure she is long gone.

She was a "programmer" in WW2, a nun who taught us "front paneling", Basic, and Fortran.

She programmed ballistic tables for Naval guns and Artillery using a slide rule when she worked in places without electricity.

 

[Bottom Fodder]

I’m just glad it’s not mandatory that you weigh primers just an option for those who like to

 

[memilanuk]

Most cheap calculators will have an Average and Standard Deviation (sigma) on there and we have taught uneducated third world peasants to run QC samples.

It really isn't hard, our schools just suck.

Those peasants probably didn't brag about their ignorance of math more complicated than 2+2=4, either.

 

[Rocketvapor]

and now page 5
If you can find an outlier from 30 to 100 primers, you is either unlucky, or got a bad batch.
MAYBE one or two light and/or one of two heavy per 1000. Maybe in one brick, but not another.
Count your Sigmas. A true outlier will be 0.1% of product or less of a process in control.
For those shooting a group with light primers and another group with heavy primers and expecting to see a difference, good luck. Those where ALL good primers. I would also NOT expect to see any difference within the first few hundred yards.
Use grains, grins or grams. Just have the resolution to see "bins".
Here is one brick of CCI450 primers, sorted to about 0.02 grains. I would NOT expect to see ANY difference in performance with any close to the mean. I did not shoot the extremes. Maybe one day.

That's a range of 0.165 grains.
Can your shooting discipline live with a few odd shots per thousand?