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Old May 11, 2012, 08:45 PM   #1
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Can Primer Brand Affect Accuracy?

I have been reloading .223 for my AR this past year and have tried out various grain bullets, different powders and grain charges to find what appears to be the most accurate for this particular rifle. It is a BCM with 16" barrel, 1:7 twist and my most accurate set up so far is the 65 grain Sierra Gameking with a 25.5 grain charge of H4895 and using Winchester small rifle primers. Yesterday I received a new order of powder and primers and this time ordered some Tula .223 Small Rifle primers because they were available and less costly than the Winchester primers I have bought in the past. I loaded up 24 rounds of the set up described above but used the Tula primers instead of the Winchester primers as in the past. I consider myself a mediocre shot but have achieved some 3" groups of 6 shots at 100 yards in the past with this AR. To my surprise today my first group of 6 shots at 100 yards were all within 1 inch! Can just changing primers do this or did I just have my best session ever with this rifle by coinsidence? Next week when time allows I plan on trying out the 2 different brand primers back to back to compare shot placement as I did not have the time to do so today. Thanks...
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Old May 11, 2012, 08:50 PM   #2
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Sheet happens. Load some more and test again.
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Old May 11, 2012, 09:24 PM   #3
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Some have recorded those primers to be a little hotter then the US primers are. That could be case. It might allow the powder to burn better in some cases. The only way to tell is to load up a bigger batch and try them to see if the pattern continues. Many have said when you change a component you should always work the round up again to try to compensate for any changes there might be. It is also possible you didn't fully work up your load using Winchester primers before and just needed another 0.1 of a grain of powder to make it more accurate in the past.

If you load up another batch of ammo and it works just as well for you, I suggest you grab a bunch of those primers for future loading.
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Old May 11, 2012, 09:39 PM   #4
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In a word, yes. You wouldn't be the first guy to cut group size in half or better just by changing primers.

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Old May 12, 2012, 01:08 AM   #5
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+1 yes primer brand can affect accuracy. Its not something that will ALWAYS affect it, but it definatly can.
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Old May 12, 2012, 01:41 AM   #6
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Absolutely ! Primers can also effect pressure .You can also get presssure excursions [some primers in the box giving very high pressure] or the opposite some primers pushing the bulet into the barrel without igniting the powder. !!!
And Watson , bring your revolver !
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Old May 12, 2012, 05:01 AM   #7
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Changing anything can effect accuracy, not saying it will, but it can.
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Old May 12, 2012, 05:53 AM   #8
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Have you tried CCI primers ? I would be interested in seeing any change if any with them.
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Old May 12, 2012, 07:51 AM   #9
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Misssissippi Dave,
I measure each and every load with my scale so I know the powder charges were as similiar as possible using both brands of primers.

Next week I'll load up a small batch of shellls using both brands of primers and run the loads through my chronograph as well as at the targets so I can find out for sure if the change in accuracy was due to the primers or just me having a good day. I will load the separate groups of reloads into different marked mags and will not know which load I am shooting first until afterwards. The Tula primers may be burning a bit hotter than the Winchester, I thought I noticed a slight increase in recoil, but that is highly subjective on my part and I may be wrong.
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Old May 12, 2012, 03:32 PM   #10
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I switched from Winchester small rifle primers to Remington No.7½ bench rest rifle primers in my .223 loads. Same bullet and powder charge. Cut the 100 yard group size from 0.9 inches to 0.6 inches. So yes, different primers can change group sizes.
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Old May 13, 2012, 08:37 PM   #11
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I tested this out awhile back.
In my 30-06 I used the same load and bullet, but changed from Rem, Win, CCI and Fed primers. All large rifle (no mags) primers.

The groups ranged from 2" - 3/4" and 200fps difference with Remington being the smallest and fastest groups of the lot.

That was MY gun and since all guns are different, your results could easily be different.

But the simple answer is yes, it can make a big difference.
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Old May 13, 2012, 09:32 PM   #12
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The thing it keep in mind, is that primers are just like every other component in a cartridge. The powder you use and the amount can make a difference in accuracy, the bullet itself can make a difference, so why should it be surprising that the primer can make a difference?

No brand of primer is "more accurate" than another, its all about what your gun likes.
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Old May 13, 2012, 09:59 PM   #13
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Well, now I know what load to try with my Sierra Gamekings since I have some 4895 laying about. I use Remington 7.5, also in a 16 inch barrel, will chrono and document - are you shooting off a rest?
__________________ same original CZForum, new location.
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Old June 2, 2012, 12:03 PM   #14
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Primers can definitely affect accuracy. Just as different powders have burn rates that vary so do the primers. Powders can react differently under a host of different influences such as outside temperature and changes in powder volume. Different primers have their own nuances as well such as the initial exsplosive force we refer to as hotter vs. colder and also their capability to be uniform in their combustion output. This is why you see primers labled with terms such as magnum, benchrest, match and sometimes standard. I too wish it were more simple but have to admit I enjoy the game of pursuing the elusive "perfect round" for any particular firearm. Makes me have to go shooting more often and gives you that gratifaction when it all comes together. I own no match grade firearms,,, just get them to shoot that way.

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Old June 2, 2012, 02:09 PM   #15
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"are you shooting off a rest?"

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Old June 2, 2012, 02:48 PM   #16
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Effect of primers on accuracy

In the last issue of "Varmint Rifles and Cartridges" there was an excellent aritcle about a test using a 223 with identical loads, the only difference being the primers. The test was well constructed and the results are very interesting.

I would recommend every hand loader read the article. Written by Charles E. Petty.

In reality, nobody can test your loads and rifle for you. Each loader has to perform the experiments to find which recipe will yield satisfactory results. Over the last few years Remington primers have risen to the top of my list for small rifle usage. Winchester is the "go to" primer for large rifle. YMMV.
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Old June 2, 2012, 03:35 PM   #17
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I recently read that article that Colorado Redneck mentioned. Very interesting read. I use CCI Bench Rest primers in all my rifles and I was happy to see that the article had only good things to say about those primers. Also in that article was a flat out firm statement by the author that SD had absolutely nothing to do with accuracy. His data did support that, but interpretation of data can be subjective. For instance, my wife can drop something in the kitchen and break it, but in a very short time the accident has become my fault. And she'll have data to support that.
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Old June 2, 2012, 07:20 PM   #18
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This is super secret so don't spread the word.

Those Russian primers are very good primers.

I shot some Tula7.62 and Wolf primers in a 30-06 primer test. The Russian primers were as good as if not better than Winchester, Federal, CCI 200, CCI #34's. I was very surprised how good the groups with the Russian primers.

Hush now and don't drive the prices of these primers up.
If I'm not shooting, I'm reloading.
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Old June 2, 2012, 08:29 PM   #19
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mete mentions:
You can also get presssure excursions [some primers in the box giving very high pressure] or the opposite some primers pushing the bulet into the barrel without igniting the powder.
Never heard of some primers in a box giving very high pressures.

I doubt anyone can shoot a bullet out of a centerfire rifle case larger than a .22-250 with just the primer going off and no powder or non-burning powder in the case. I shot 20 7.62 NATO rounds one afternoon with no powder under the Sierra 190's in their neck. Only sound was the click of the Garand's hammer falling on the bolt driving the firing pin hard into the primer. All bullets stayed in place. Pulling several bullets showed black soot on their base as well as all over inside the case. None of the primers backed out of their pockets.

Many folks have loaded center fire handloads in their rifles without powder just to see what happens. Primers pop but the bullet stays in the case. There's just not enough pressure creating the force to push a bullet out of a case neck when 30 to 40 pounds of force is needed.

On the other hand, .22 BB and CB caps oft times don't have powder and only the primer shoots out the bullet. A .22 long rifle without powder will usually shoot the bullet at least 15 to 20 inches down the bore. Several handgun cartridges without powder in them will drive a bullet out of the case and into the barrel or just lodge the bullet in a revolver's throat locking the cylinder with half the bullet still in the cylinder.
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Old June 2, 2012, 09:03 PM   #20
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i was always told the hotter the better ive used cci mags for years was told they were hottest at that time
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Old June 2, 2012, 10:22 PM   #21
Bart B.
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Interesting info on primers; large rifle first:

then small rifle ones:

Check the photos of the flash several make. Quite a difference. Especially the part in the large rifle primer tests:
We begin our process of data interpretation by bearing in mind Bob’s (Bob Jensen) early tests with the primer-powered, BB firing Model 70. Those test showed that the primers which produced the lowest velocities with reasonable SD in the Model 70 “BB gun” were the most accurate at 600 to 1000 yards when loaded in .308 ammunition. In fact, our own testing with the 6BR showed that the most accurate primers at 600 yards were those which produced the lowest velocities.
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Old June 3, 2012, 08:34 PM   #22
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Some primers are hotter than others, and my chronographing show that velocity increases by about 50 fps. when swithing to WLRM from WLR primers.

Even different brands of standard primers vary the velocity a little.

The best brands are CONSISTENT in their burning rate. That's all bench rest primers are---better quality control.

So far, haven't detected accuracy differences in hunting loads. Bench rest shooting might be a different matter.
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