Do Primers Affect Group Size?

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John Alexander posted this 29 October 2022

I'm sure that primers make a difference when inappropiate primers are used such when regular primers are used when mag primers are needed to ignite heavily coated slow burning powder.

My question is do different brand primers affect group size when used with fast or medium burning rate powders and at the velocities of normal cast bullet velocities.

I have always been agnostic (promiscuous may be a better word) about primer selection using whatever was handy. It seemed to me that if they went bang they were all the same. I once tried the Federal 205M primers used by 99.9% of jb bench resters but couldn't see any improvement. I recently used some of these in a load and rifle that I have good records on.  Nine 5-shot groups with 205M averaged substantially worse than usual with this load.  I am skeptical but will try to repeat and see what happens.

Anecdotal evidence abounds about one primer or another causing either better or worse groups, but have there been any serious tests that have found repeatable differences in accuracy with different primer brands?

John

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Hornet posted this 31 October 2022

Do different brand primers affect group size when used with fast or medium burning rate powders and at the velocities of normal cast bullet velocities?  Yes.

Oh, you want a little detail? Picky, picky.. Example: Remington 799, .22 K-Hornet, 1:12" twist, NOE 225-60-RN, 17 BHN, 59.5 +/- 0.1grain,  fireformed WW Cases, 5 shot groups,  AA1680 powder 9.3,9.5,9.7,9.9,10.1grains, WSR vs WSP, alternating groups between primers.   Result: groups using WSR were more rounded and visibly averaging smaller than the WSP groups. Repeated a few days later using WSR vs R-P 7-1/2, same powders charges. Result: R-P 7-1/2 groups clearly better than WSR groups. Annoyingly enough, the R-P 7-1/2 primers used were the old copper-washed version. I ran out and changed to the current brass-finish ones and groups got significantly worse, back to matching the WSR. Really need to retry with R-P vs Fed 205M some day.

Similar testing with the RCBS 22-055-FN (Cramer hollow-pointed version) showed a similar pattern with IMR 4227 in doses of 9.8, 10.0, 10.2, and 10.4 grains and those used R-P 7-1/2, WSR and Fed 205M with the Fed 205M clearly best. Disappointing since the .222 and .223 also prefer the Fed 205M in similar testing in loads around 2100 fps with SR4759 and use large quantities of them. I may need to try a faster powder for the R-P's to work (got lots of them).

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John Carlson posted this 23 November 2022

A "serious" or valid test needs to evaluate only one variable.  In the case I described I actually made 5 tests.  Each test compared a five shot group using the Federal primer with a five shot group using the CCI primer.  The loads were identical in every other respect. 

To be valid I will need to be able to repeat this test achieving the same results'

HOWEVER

No matter how many times I repeat this test it can only prove that there is or is not a difference in accuracy using this cartridge in this rifle using these two primers. 

A definitive answer to John's original question will require a bunch of tests using different loads in different rifles comparing a different pair of primers (if you can find them).

John Carlson. CBA Director of Military Competition.

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Bud Hyett posted this 30 October 2022

Thought One: Based on experimenting a half-century ago, you can find a difference in primers. You might wear a barrel out getting there. 

I had only two centerfire rifles, a 788 .222 Remington and a 700 BDL .270 Winchester. Both shot sub-minute ten-shot groups. The .222 with Sierra 53 grain Match and the .270 with Sierra 90 Hollowpoint. Remington  standard primers in both rifles. Then I was given a carton of W-W 8 1/2 primers (wooden trays) to use.

I substituted these primers and the rifle did not shoot as well. The groups were minute and one-half and not going down, interesting. I raised and lowered the powder charge, no help. Then I moved to powder one burning rate slower and one powder rate slower raising and lowering the powder charge. Then I moved to powder two burning rates slower and two powder rates slower raising and lowering the powder charge.

Eventually I found a load shooting near the original. But I'd put over 500 test rounds through the barrel in the journey. 

Thought Two:

Primers (design philosophy):

  • Federal and Winchester are designed to throw the flame forward and ignite the powder column from the center outward.
  • CCI is designed to throw the flame outward at the back of the powder column to ignite the powder column to burn progressively forward to the front.
  • Remington throw the flame in a 45-degree angle to ignite the center and burn both outward and forward.
  • With the shorter, fatter, sharp-shouldered cases in use today, the CCI primer is gaining more usage.
  • I find when switching there is a load with a slightly faster or slightly slower powder that will shoot consistently as the first load.
  • Therefore, I standardize on a primer for a load and work forward. 
  • Federal or Winchester for long cases (.e.g., 30-'06), Remington or CCI for shorter cases (e.g., 6mm BR)

 

Farm boy from Illinois, living in the magical Pacific Northwest

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JeffinNZ posted this 30 October 2022

Depends.  

My Hornet is fussy with primers depending on powder.  Stick powder not so much.  Ball powder, will only shoot with Winchester primers presumably as they are hotter.

I tend to think small cartridges can be picky about primers.  Large cartridges, no.

Cheers from New Zealand

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John Carlson posted this 22 November 2022

Finally got some weather conducive to something other than practicing reading the wind.  I've been considering the use of Large Pistol primers and had a batch loaded up.  Rifle is the Howa 1500 in 7.62x39.  Ive never been able to consistently squeeze anything better than ok from this rig and wasn't surprised today.

The load was the Lee 312155 bullet over 14.8 gn of Buffalo Rifle. 25 rounds with Federal 215 primers and 25 rounds with CCI 350 Large Pistol Magnum primers fired in alternating five shot groups.  Results as follows.

                                             Fed                  CCI

Average group size               1.877               1.851

Average velocity                     1508               1484

Max velocity spread               50                     70

Standard deviation                  20                     26

While the chrono data may hint at a difference there doesn't seem to be an advantage.  I do happen to have another 50 cases primed so I'll just have to decide what to match them up with and wait for another nice day.

 

John Carlson. CBA Director of Military Competition.

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Fitzpatrick posted this 30 October 2022

Over the last couple of years I have been forced to try different primers in different calibers . I have come to the conclusion that if I work up the load you can achieve the same group size with in reason , I did have some hang fires in 308 based wildcats that I tried small primers in but even then using pistol powder solved most of that. Of course accuracy is in the eye of the beholder , if I can get a load to group at around a inch at a 100 yrds  that is a good hunting round . But in the end I think if loads are developed with a primer that you have on hand you can achieve acceptable results , with the exception of bench rest competition . and all my testing reloaded primers was also used with the same accuracy 1 moa  and continued shooting and enjoyment thou this time of no components

 

  just my two cents  James

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Rich/WIS posted this 30 October 2022

Not an opinion on accuracy (me and my rifles are not good enougn to tell) but did notice that had occasional delays in ignition with ballpowders and standard primers.  I use magnum primers with Ball C2 and Win 748, standard with others.  Noticed the delay when shooting with electronic ear muffs, most went bang when the firing pin hit but a few there were a few where you heard a click-bang.

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Wineman posted this 30 October 2022

I have shot 308 Win in an Ishapore 2A1 using Winchester LP primers, a 312299 and 15.5 grains of Alliant 2400. First shot pierced the primer, stopped there and broke that ammo down. Accuracy was good, but hard on the gun.

Dave

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Tom Acheson posted this 31 October 2022

For my CBA benchrest match guns, I’ve been using small rifle BR primers since 2005. Accuracy testing each time I changed to a different chambering, had me using R-P 7 ½ or FC 205M primers, depending on the chambering. For my revolver loads using large primers, I’ve found most brands do OK. Interesting that there are now some 45 ACP cases that use small pistol primers.

 

However, for my black powder cartridge loads, I’ve seen a trend of accuracy improvement where FC 150 (large pistol) match primers, along with a disc of wax paper dropped into the case before the powder goes in, is working well. Supposedly the wax paper softens, diffuses or spreads the primer “flame” to optimize ignition. Other shooter’s have commented that the shorter pistol primers (in the primer pocket) contribute to peening of the face of the breech block. In doing this for the past 5-years, I see no evidence of that in my rifle. It’s a C Sharps Model 74 chambered in 40 cal. 2 ½.

 

Tom

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Wm Cook posted this 01 November 2022

Rick here's some numbers that I just pulled off my computer this week.  I was hoping to get out once more this year to give these loads a try. So I was getting my ducks in a row for the next range trip.  All 5 shot 100 yards, mixed Fed and Rem SR. Wasn't smart enough then to shoot 10, 20 shot groups..

So I thought these were the best of the powders and loads to look at again.  I also tried Lil Gun, 2400, 5744 and W231 and they didn't shoot as well.  Some of those groups were real ugly  Some over 10".  But I was shooting velocities from 700 to maybe 1300 fps.  Bill C

 

 

 

 

Patience isn’t a virtue, it’s a delay tactic.

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Wm Cook posted this 03 November 2022

About primer selection: I'll follow this tomorrow with data from the Nationals to see common threads to primers, cartridges and class.  As a lead in I'll say that selection of primer is distinct to each class but not distinct to cartridge.  I'll try to post tomorrow.

I apologize to John in advance for the diversion on the thread but I thought this might help some folks.

Regarding 225438 / Unique.  This is just a raw data dump sorted by charge weight.  If you're working with Unique and 225438 this'll give you some idea the velocity ladder I found with the couple of bottles of Unique I had used over the last bunch of years.  As I ran the velocity up I was getting too many fliers which I know could have been caused many things.  I settled on a low velocity load as the path with the least resistance.  And I was shooting a suppressor so it made a nice pop sound. 

As usual the standard cautions should be applied.  Take care, Bill.

Patience isn’t a virtue, it’s a delay tactic.

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4060may posted this 09 November 2022

I noticed there was no mention of Wolf, or Fiocchi, I have shot a lot of Black Powder Cartridge, Both Silhouette and paper

Wolf primers in my rifle 40-60 Maynard RB, 38-50 Rem Hepburn, 40-72 CPA, 38-50 Rem CPA, all of these give me vertical stringing with Wolf Large Pistol primers, the current wisdom at the time and I guess still is Pistol primers and BP work better, I went to Fiocchi Large Pistol primers, the SD was OK, but the group was round and tighter than Wolf, I also used Federal LP, better SD but the group was no better, this is at 200-300yds

Tried Mag primers both Rifle and pistol, WLRM, and F215, worked OK is pistol primers were not available.

picked up some Fiocchi, small rifle primers, green colored priming compound, found out later these were green primers, 1500 to the brick was 29.00, no longer available I was told by the importer, used them anywhere a small primer was needed, .357max, mag, 32-20, both rifle, shot well with the powder I used, 7625, loaded some .357 max for deer with 180gr XTP bullets and WC680, almost a full case, Fioccchi small Rifle Primers would not light the powder up, left the powder yellow and in a clump

In the Schuetzen game with Breech seated PB bullets and SR4759,Rem 2 1/2 primers was the standard, never worked for me...

Burn rate charts are nice to look at, but do not give pressure curves for particular cartridges

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Wm Cook posted this 14 November 2022

Lucky 1 said: “ I just try to be optimistic on double strike primers and refer to it as "dry fire practice ".

Thanks. Laughed my butt off. It’s happened to all of us and we all have that same dumb look on our face when it goes click instead of “bang”. Bill.

Patience isn’t a virtue, it’s a delay tactic.

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John Alexander posted this 22 November 2022

Not familiar with the term, but think I may be the OP so will try to answer.

Off the top of my head it seems to me that a serious test that advances what we know requires at least two features.

One is to be planned ahead of time and designed to answer a specific question about a limited number of variables.

After the shooter thinks he has found the answer to the specific question asked, enough additional groups are fired to confirm that the answer is real and not just an artifact of the group to group variation that most of us badly under estimate.  

A couple of years ago I wrote a Fouling Shot article on my thoughts on running a good experiment.  I am away from home for Thanksgiving so can't say what issue it was in.  Will look it up when I get home if anybody wants to take a look.

I would be interested in what others think is required to qualify as a serious (probably valid) test.

John

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Hornet posted this 01 November 2022

I was reading Ness's Practical Dope on the .22 and he mentions that H. Guy Loverin said to seat the 225438 to NOT touch the rifling. He recommended 3.0 Grains of Unique for squirrel, etc and said they'd gone as high as 10.5 grains of 2400 (2750 FPS!!). Something to think about.

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Hornet posted this 03 November 2022

Nice data accumulation !!! I like the documenting of group size variation with the same load. It kind of illustrates the sheer joy of load development with cast in the Hornet.

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John Alexander posted this 03 November 2022

It isn't just the Hornet or just cast. All calibers and all levels of accuracy. from 0.2 to 40 minute of angle, have variations in accuracy similar to these for any one load.  It shows up in any group match. If this seems unbelievable see the article on tuning in Fouling Shot #275.  We seldom see this because very few shooters do what Bill presented above (multiple results of one load) -- but maybe we should think about it.

John

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John Alexander posted this 08 November 2022

Thanks for taking the time to ferret this out and post it. Interesting bunch of data points. To me this says that a fairly wide range of burning rates can produce competitive results in the same case and bullet weight. Not too surprising. The fastest pistol powders have won quite a few CBA matches, some in cases five times optimum size, and If I remember correctly Col. Harrison was a proponent of very slow powders like 4831 for cast bullets. 

I think we have a bunch of facts and principles about CB shooting( such as "slower powders give the bullet a gentler push and reduce deformation and aid accuracy" or "JBs are harder and shoot better than CBs so harder CBs should be better") that the actual cast bullets have apparently not read about. The older I get, the more it seems that the correct answer to almost all CB questions is " that depends on the situation."  There may be just one hard rule as Ken says.

That is part of the fun and challenge of our screwy hobby. If a shooter finds that more frustrating than entertaining he should consider jacketed benchrest where the exact recipe is handed to you on day one. Then you can go forth and pretend to be able to tell how a rifle and load are shooting by looking real hard at a single three or five shot group.

Yeah, I know this isn't contributing to answering the question posed in post #1. But that was a hard question.

John

 

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RicinYakima posted this 09 November 2022

Breach sitting is a different animal that shooting from a case. 

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lotech posted this 09 November 2022

John-

You  mentioned in your original post about different primers used with fast and medium burn rate powders at normal cast bullet velocities.To begin such testing and do it right where the results provided truly useful information, you'd probably have to narrow your parameters even more, say pick one appropriate fast powder per series of tests. Using every suitable primer (I don't know how many that is offhand), it would still be necessary to do some fine tuning of powder charges with each primer, then shoot as many five-shot groups as it would take to satisfy either normal curiosity or obsessive fanaticism, whichever one your tendencies lean toward. 

This would be an incredibly huge task and one that's probably never been done. As Dave Scovill, the former long-time editor of HANDLOADER and RIFLE magazines put it one time when describing a compex and time consuming handloading project that might eventually develop into an article: "It's  like chewing a piece of gristle that gets bigger as you chew it." And it doesn't taste good either. For those who aren't familiar with Scovill's work, he did some pretty detailed cast bullet handloading projects, but that was many years ago. 

Many of us have tried the lazy way to find the best primer but often fool ourselves with the simplicity. We develop a very accurate load with one primer, then switch primers only and don't touch the load itself. The informatiom obtained is of dubious value at best. Working up a load with each primer is of real usefulness, but that's a lot more work. 

 

 

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