PRIMER CHOICE

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Last Post 29 April 2019

CBA Member

joeb33050 posted this 24 April 2019

There are a few questions.

Are small primers more accurate than large primers?

Does firing pin strike force variation vary accuracy?

We have the report of Charlie Dell’s test, saying NO. Stevens 44 1/2 rifles, I’m told, have adjustable firing pin force. Testing is simple.

Does primer choice affect accuracy?

My experience and testing says NO, that either the primer sets off the powder charge, or it doesn’t. If the gun fires, accuracy does not vary with primer choice.

My test results for primer choice with cast and jacketed bullets are not satisfactory, other variables are included and/or sample sizes are too small.

A search of the internet found no reports of reasonable tests. There are reports about brisance and primer energy and cup dimensions and anvil location; but the reports that I found connecting primer choice and accuracy have distressingly small sample sizes.

One of the reports counts primer choice in loads recommended by competent shooters. This seems to be a reasonable though fuzzy way to look at the question, so I did.

CBA NM primer choice, by place, (1 = first, 2 = second,&hellip.

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joeb33050 posted this 24 April 2019

These tables suggest that there is no much-more-accurate primer, else it would appear in greater numbers. Unfortunately, this suggestion is based on the assumption that the shooters have conducted tests, which may be/probably is, false.

It is NOT possible to prove that there is NO shooter/bullet/gun combination that shoots smaller groups with one primer than another.

If a shooter/bullet/gun combination IS found that shoots smaller groups with one primer than another, with reasonable sample size; then we can examine the better primer’s characteristics and perhaps make progress toward improved accuracy.

So, I’m looking for tests and test reports, with a reasonable sample size, showing that primer A shoots more accurately than primer B. A reasonable sample size is five, 5-shot, 100-yard groups.

(All other data is on castbulletinfo, a yahoo group.)

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CBA Member

Ken Campbell Iowa posted this 24 April 2019

here are results of a google search for discussions of primers by very obsessive shooters within Benchrest.com.

many shoot teensy little groups with mj bullets; but remember there are also opinions of shooters who choose primers because of the artwork on the primer box.

https://www.google.com/search?sitesearch=benchrest.com&q=primers&submit.x=0&submit.y=0&domains=benchrest.com

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CBA Board

John Carlson posted this 25 April 2019

When I played around with BR and MJ a few years ago I did some limited tests comparing 5 different primers. Sorry I have discarded the data (might know I'd need it as soon as I threw it away!). As I remember while I did identify repeatable differences in velocities, including differences in extreme spread and standard deviation, I never found an accuracy advantage. Even the higher prices of some brands didn't produce tighter groups.

John Carlson. CBA Director of Military Competition.

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RicinYakima posted this 25 April 2019

Like John, I played with primers after I bought my first Chrony. And like him, I could note number differences, but never any difference in group size over a long run of 10 shot groups. Like JoeB alludes to, if the firing train will ignite the primer, that is all that is required.

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tlkeizer posted this 25 April 2019

Greetings,

In my Speer reloading manual, latest edition when I bought it a few years ago, they addressed primers and differences. In particular, they addressed primers used in black powder loads as they seemed to make a bigger difference there than with modern powders. If you have a Speer Reloading Manual, you may want to read what they have. If I remember correctly, they address pressure curves relative to primers too. I found it interesting to read. And, if I remember correctly about this also, accuracy did not really vary. Of course, my memory is older this week than last week, but I do recommend reading what Speer found out.

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GWarden posted this 26 April 2019

Primers do make a difference in. OK, before anyone gets their shorts in a bind, let me explain. It has been alluded to in a few comments that with different powder one will get better burning of the powder so there is not unburnt powder in the barrel. When using Alliant 300mp powder one needs to use LRM primers. This has been proven by one of the shooters over on the ASSRA forum, he has used over 40# of this powder and has the results to show that mag primers are required. I back up his results with my test in a 32/40 and 38/55. In these test the bullets were being breech seated and using a soft mix of 25:1. Would one get the same results using fixed ammo with hard bullets in a accurate. bolt rifle, not sure. I did try the 300mp in my 6mm Rem. 700V the other day. There were several factors that varied from using imr4198 with a hard cast bullet. The load with the 4198 gave the best accuracy in my rifle when the bullets were having to jump .030+ for best accuracy. This info can also be found in an article by Jim Carmichael several years ago in his test on seating dept. If anyone would like a copy of his article on seating depth in the 6mm's I will be glad to send a copy.

Ok, back to my test with primers. In my 6mm I was using the RCBS 95 gr. cast bullet without a GC attached and a bullet mix of 25:1. used 8.9gr of 300mp and the best accuracy was with mag primers. BUT, again was using a softer bullet mix, and seating the bullets out into the rifling. With hard bullets and 4198 regular LR primers gave the best accuracy with the .030+ jump. SO, what in the heck does all this prove. We cannot make a blanket statement that primers have no change on accuracy. Too many other variable when working up a good load. OK, let er rip, I got my big boy pants on.

bob

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RicinYakima posted this 26 April 2019

Bob, you will have no argument from me for specific powders or circumstances. With my '06 and 220 grains Hornady bullet and a compressed load of surplus 4831, only the Fed 215 or WW LR Mag primers will light it off reliably when it is cold. With my CBA match load of 16 grains of A2400, I have used Fed, Rem, WW, Tula, CCI and RWS and never found a bit of difference on the target. FWIW

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JeffinNZ posted this 26 April 2019

My .22 Hornet will not shoot Lil Gun accurately without a Win small rifle primer. Anything else is terrible.

Cheers from New Zealand

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Shopdog posted this 27 April 2019

My experience has been.....

The larger the tune window,the less primer choice matters.

Loads that are on the edge,for whatever reason..... primers can be a make it or break it choice.

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Bud Hyett posted this 27 April 2019

When starting, I asked several veteran reloaders about primer choice. The results were all over the map.

Deciding to experiment, I owned two rifles accurate enough to be able to discern the tests. My choices were Remington 9 1//2, Winchester Large Rifle, Federal Large Rifle for the 6mm-.250; Remington 7 1/2, CCI Small Rifle, and Winchester Small Rifle for the .222. Bullets were the Sierra 6mm 70 grain flat-base hollowpoint and the Sierra 53 grain Hollow-point Match bullet. I've lost the data, too many moves before it could be put on a thumb drive.

The conclusion was that primers do make a difference. I could duplicate accuracy of one load with a different primer.and a different powder. I possibly wore out the throat of the .222 while testing. A load in the 6mm-.250 that shot well with H380 powder with Remington 9 1/2's would be duplicated by IMR 4064 and Winchester Large Rifle primers. The results were with five-shot groups.

From this, I concluded that standardizing on a primer when developing loads is the best choice. A person can wear out a barrel searching for the perfect load.

Farm boy from Illinois, living in the magical Pacific Northwest

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45 2.1 posted this 27 April 2019

From this, I concluded that standardizing on a primer when developing loads is the best choice. A person can wear out a barrel searching for the perfect load.

I never had a problem with wearing out the barrel with properly alloyed lead (they were just well polished)........ though some revolvers and semi-autos needed a serious refit.

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Bud Hyett posted this 28 April 2019

Changing the subject slightly.

About three decades ago at a match in Cajon Pass, I had the opportunity to look down the bore of a Remington Creedmore .44-77 that had only been shot with paper-patched bullets. The current owner had bought the rifle and the complete kit including the tools to cut patches and a supply of paper.

I have never seen a smoother, shinier bore.

Farm boy from Illinois, living in the magical Pacific Northwest

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Ken Campbell Iowa posted this 28 April 2019

i think the cba should develop some designated shortcut keys that could save a lot of typing time describing cast bullets .

needed single key codes for following words::

maybe.........sometimes ..... quiteoften ..... occasionally ...... ithink ...... iwonder ...... onetimei ...... neveragain ..... whatheheck? ....

ken

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pat i. posted this 28 April 2019

I've often read and heard Federal made the best primers. At a gun show years ago a guy used to sell bricks of Winchester small and large primers for 10 bucks a brick and I bought a ton. My decision on what primers to use was made for me not by me.

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TRKakaCatWhisperer posted this 29 April 2019

My experience has been..... The larger the tune window,the less primer choice matters. Loads that are on the edge,for whatever reason..... primers can be a make it or break it choice.