Testing primers

[lastshot]

If I remember correctly Brian litz said that "after powder, primers were the second thing that affected fps the most" so the change on es and sd would be evident on SOME rifles.

 

[skipglo]

I've read that changing primers can effect accuracy and ES when the right one is found. I've always wanted to test it for my self and am gearing up for it. How do you test your loads with different primers but keep the round count down to save barrel life and components? Since ES is a testing parameter, seems that 5 shot groups would be a minimum.

How would you go about testing them without redoing a full load workup? 338 components aren't cheap and I'm on my last keg of Retumbo.

If you currently have a good load that you are real happy with 5 rounds will tell you more than enough. Don't change your powder, or the grains..just like you said...only the primer. I have used Fed 215 and Fed 210 for many many years and was blown away by the difference ( bad) that Fed 215 match made....stupid me... I thought WOW MATCH GRADE PRIMERS...bought a sleeve...1000 primers....jumped right in hook line and sinker. Loaded 50....shot ten rounds not believing the first five....thought maybe I had contracted super aggressive muscular dystrophy! Pulled 40 bullets, dumped the powder back, punched the primers out and through out 940 primers! So the short form morale of the story....5 should do it!

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[crkckr]

Since every rifle is unique some will be more affected by primer change than others. It also depends on the potential accuracy of each rifle. The bottom line is, if you can prove - to yourself, at the very least - that one primer has better numbers than other primers, it's pretty clear that's what you should be using. If you have the numbers, it's not opinion, it's fact.

I suspect that where problems may insert themselves is in the consistency of each brand of primer. I know they all strive to make each batch the same as the last one, however some may be better at it than others. Plus it could depend on the makers 'standards' as well. If you're loading on that ragged edge of pressure then it might be wise to do some testing each time you're forced to change lots of both powder and primers. While I don't have numbers to prove it, I suspect that powder has more potential to effect the bottom line than primers. Then again, if you're trying eke out that last 0.01" of accuracy, primers certainly could play a role. Test, test, test is the only way to prove to yourself that the individual lots are the same. It's what keeps many of us at the reloading bench!
Cheers,
crkckr

 

[L.Sherm]

I shoot the ones that are the most accurate. Test them at atleast 500 you will see a difference.

 

[J E Custom]

It is just My opinion based on experience with different primers that different primers will/can Improve SDs. What works best for me is to take a load with already good SDs because the bullet weight, powder and case capacity are a good combination and work well combined. armed with an already good load, I chose other brands of primers that are in the same class and Brisance (Only change one component at a time) I like to shoot at least 5 rounds of each test loads, starting with a clean barrel each time. This assures an apples to apples test.

Revue the results and look for the best SD. what this test method tells you is which primer is best for that load with that group of components. It may also encourage you to try other powders with the same bullet weight and case capacity to find out if there are better primers for that cartridge using that Primer.

This also tells you that a particular primer works better for that Powder. Even slight improvements in SDs do contribute to better accuracy at longer distances, where at close distance it is hard to recognize this improvement. One such rifle of mine went from a SD of .07 to .05 and improved the group size from .071 5 shots @ 100 yards to .054 Not a huge improvement in ether SDs or group size bur a large Percentage improvement and at distances of 400 to 1000 yards, a significant improvement.

Test your rifle and find out what primer it likes best. Just because someone else uses one brand, doesn't mean your rifle will like the same primer.

The match grade primers "Should" be better because of quality control requirements. But don't depend on this, because different combinations of powders, bullets, cases react differently and in many cases the standard primer can/will produce better results.

J E CUSTOM

 

[jrock]

The gun is 1/4 MOA on a bad day so on paper it shoots great. ES is 30 with SD in the teens and sample size is still low. I also have a factory .243 that shoots about 1/2 MOA but the ES values are in the 40's. So depending on what the 338 does with primers, I might switch from the .243 as well. I have to say that I have chrony so standard errors and light conditions could be skewing my data.

 

[hpmag308]

I use federal mag primers for both mag an large rifle. Not much difference if any in price an you don't have to worry about keeping them separate

 

[Wedgy]

I have to say that I have chrony so standard errors and light conditions could be skewing my data.

The best thing that ever happened was when my buddy borrowed mine and shot it, I then got a MS and Labradar and all the craziness went away. Same thing when I got a good scale, the FX120.... no more scratching my head.

 

[TRG65]

I've tried magnum primers in a couple of "magnum" loads, 7WSM and 338WM. However, even match magnum primers gave poor SD's and ES's. When I put in the CCI LR BRs, the groups and the SD's shrunk. The 7WSM load was 65'ish grs of powder and the 338WM is 71.5. Both have been shot in the cold and work just fine. If I ever get a 338LM I might find a use for my magnum primers, but until then...

 

[jrock]

I've heard that LR primers in loads less than 70 grains can work better than magnum loads.

 

[keithcandler]

Nothing like trial and error.

Sherm, I found a niche for the win mag primers with R#25 in the 7Mag, SD was 9fps with amazing accuracy. Groups opened with fed 215's.

Through the decades, I have seen over and over again that a particular power may certainly have it's own preference on a primer choice.

Also, we have no control over primer quality and lot to lot variations in primer differences.

an attitude of not liking one primer over another will leade you to short changing yourself at times on serious accuracy.

There is no telling what a particular powder and bullet will like, we are humbled constantly by this.

We load at the rifle range.

[/URL]

 

[JusSayin']

https://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf
A little light reading on the subject, hope the link worked.

 

[Dave 308]

I've read that changing primers can effect accuracy and ES when the right one is found. I've always wanted to test it for my self and am gearing up for it. How do you test your loads with different primers but keep the round count down to save barrel life and components? Since ES is a testing parameter, seems that 5 shot groups would be a minimum.

This is true but to save you some time you could just use cci Primers , small rifle primers have proven to provide longer primer pocket life and better velocity spread so a cci 450 magnum with the 6.5 works well. I've gotten as low as 4 with mv so may work for you as well.

 

[J E Custom]

I've heard that LR primers in loads less than 70 grains can work better than magnum loads.

It is true in some rifles. I like to give examples that have proved this in certain rifles. My 31" barreled 7 STW went from a SD of 17 to a .04 when I switch from a Fed 215 to a Remington LR 9 1/2.

The accuracy at 600 yards also improved 100% but the velocity went down almost 40 Ft/sec. The powder charge was 87 grains of H 5010
and the Large Rifle 9 1/2 primer seamed to produce a more consistent pressure and brass life was great.

Sometimes it just pays to try different primers, but be sure you start low, especially when going to a magnum primer. Typically it is best to start with the recommended primer listed in the load data.

J E CUSTOM