Benchrest & Match primers: Any real difference?

[BumbleBug]

I've seen primers called "Benchrest" or "Match" & at an increased cost over regular primers. Is there any real difference? Can any benchrest/match shooters attest to an advantage?

TIA...

[Jeff2131]

Yes, you wouldnt know it by looking at them but the chemical compound is different.

[Bart B.]

Some of those match or benchrest primers are better than standard ones. The reverse is also true.

One year at the Nationals, I talked with a Federal rep about their primers. He said the "slurry" mix of chemicals is like putty and the person uses paddles to mix it up as uniform as possible much like mixing taffy on a granite block. It's almost a "black magic" thing to get all the chemicals uniformly distributed in that glob. Then it's smeared into plates with small round holes as evenly as possible. When it's dry, the primer pellets are removed, put in primer cups, then a seal over them and topped with a 2 or 3 leg anvil.

Quality tests involve how hard and deep they have to be dented to fire as well as testing the uniformity of their output when fired. He didn't say exactly how they test for firing uniformity (company secret), but those with extremely low spreads in it are set aside for "match" primers. All the rest in specs are sold as standard ones. Primer chemicals are the same for each type, but some lots are more uniform than others.

Interesting info on primers:

http://riflemansjournal.blogspot.com...mer-study.html

http://riflemansjournal.blogspot.com...mer-study.html

http://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

[dahermit]

Yes, you wouldnt know it by looking at them but the chemical compound is different.

That is strange...when the primer companies talk about how benchrest/target primers are made, they talk about the physical process as being more precise, not that the chemicals are different.

[Slamfire]

This is an interesting article: Mysteries And Misconceptions Of The All-Important Primerhttp://www.shootingtimes.com/2011/01...motaip_200909/

Apparently CCI weighs their benchrest primers. From other threads the CCI benchrest primer has a thinner cup and therefore is not appropriate for semi automatic rifles, as that makes the primer more likely to ignite when a free floating firing pin hits it.

What Bart heard from a Federal Representative is consistent to what a shooting bud of mine has said. His job is oversight of gauging at ammunition plants. Primer cake is still apparently mixed by hand, the consistency of which, from lot to lot, is highly random. The words my friend used was “artifact”. I think he means statistical accident. Workers whose primer mix is used in match primers do get a cash award.

I am of the opinion of the non homogeneity of primer cake is the greatest factor in the phenomena of sensitive primers. Primer cake is a mixture of components, the percentage and purity of which vary between lots. I believe that a thick goopy mix is impossible to achieve 100% consistency through the batch, so it is very possible that some primer cake is going to be more or less sensitive even though it all came from the same mix. And this is true, from seeing drop test data. Primers vary by sensitivity within the lot. It is being recognized now, with enough slamfire reports from shooters, that overly sensitive primers exist. Primers vary in sensitivity and every so often shooters get one that goes off when chambering a round , most often in AR’s and Garands. Until the middle nineties “conventional wisdom” was that the only causes for slamfires were high primers and worn out receiver bridges. That is, it is all the shooter’s fault, either sloppy reloads or a worn out rifle. The concept for primer sensitivity did not exist, there was no such thing, a primer was a primer. However, AR15’s don’t have receiver bridges and lots of slamfires were being reported with factory ammunition in AR15’s. You will still run into fools, particularly owners of M1a’s and Garands, who deign that there are any differences in sensitivity between primer brands. Most of these fools hang out on M14 forums and are very vocal about a primer is a primer is a primer.

[rg1]

Yes, I've read from several sources including the primer companies that the difference in Match-Benchrest and standard primers is simply that they put their best and most consistent employees on the Match primers spreading the mix into the cups. That's the only difference in standard and match of the same type.

[Jeff2131]

Yes, certain primers contain a different set of chemicals, different amount of chemicals, or even the placement of the anvil. The "pellet" is the actual priming compound. Different amounts, and in some cases different types of priming compound may be used, depending on primer make, size, and type. And as for match/bench rest primers....the sensitivity is increased simply by how deep the "anvil" is seated inside the cup. The closer to the bottom of the cup the more sensitive the primer. I dont hang out in an M1 forum, just here, but common sense tells me that a free floating firing pin could very plausibly set of a match/bench grade primer.

[4runnerman]

The cups are thicker to handle higher pressure loads
Standard Primer.020 cup thickness
Match and Magnum primers-.025 cup thickness
Also better quality control

[BumbleBug]

Thanks everyone for their great input & insight into primers! I've learned a lot here.

But those that are hardcore competitors, do you use match/BR primers by automatic default? Has any testing been done as to accuracy improvement?

[Bart B.]

The only time I used match primers was decades ago when learning how to load ammo as accurate as possible. Shot a few hundred each of Fed 210M avid standard ones; match ones were better at long range, no difference at short range. Switched to RWS standard ones for long range when tests showed them by far best at. 500 yards and beyond.

Tula (formerly Wolf, originally PMC) primers may be the best ones now with their good track record in competition. Those Russians make them right.

[BumbleBug]

Originally Posted by Bart B.

...Tula (formerly Wolf, originally PMC) primers may be the best ones now with their good track record in competition. Those Russians make them right.

Interesting comment/observation. Whenever I shop for primers I look for CCI's for my serious rifle loads & only consider the "cheapie" Wolf's (normally about $10 less per K) for my pistol plinking!!

Gee, I learn sumpin' new everyday...

...bug

[4runnerman]

Bumblebg- I am with you there CCI only for me too. I don't doubt Bart though.
I have gotten to the point that I will never even buy wolf ammo. It is just pure junk,but maybe their primers deserve a try. 2 ruger 10/22's 500 box of wolf ammo. Every 3rd or 4th shot was a miss fire. Gave them away to another guy that shoots 22 pistol. He said they would not even cycle the action.

[HAMMER1DOWN]

I shoot wolf primers exclusively in everything but my handguns and that's just because I don't have them for them yet. My .308, 7x57, .223 and .300 WM loads shoot great and are all extremely accurate. I used to shoot just CCI until I bought 5k for my AR and seen that my accuracy wasn't affect in the least. Not to mention that they are cheaper.

[Bart B.]

One thing the benchresters learned decades ago on primer seating. . . .

They gotta be seated deep enough to get a good pre-load pressure on the by the anvil pressing hard against the primer pocket bottom. Primers not fully seated to the right depth won't perform as uniformly as those that are.

And firing pin spring strength has to be up to specs (sometimes 5 to10 percent more); weak ones cause irregular primer performance regardless of how they're seated.

Ensure the firing pin sticks out of the bolt face when full forward at least .055". If that dimension gets less and less, primers won't get sufficient dents to fire them uniformly. Keeping head clearance on reloads to less than .004" helps in this issue. Case headspace should not be more than .004" less than chamber headspace; head clearance equals chamber headspace minus case headspace.

[Jeff2131]

Agreed...when the primer bottoms out in the pocket, the anvil is slightly pushed closer to the foil and pellet thus increasing the sensitivitey of the primer. Another good reason to properly clean primer pockets!

[Bart B.]

It's been my experience that best accuracy happens when the anvil's slightly compressing the primer pellet. Least amount of vertical shot stringing happens doing this.

http://riflemansjournal.blogspot.com...e-and-pre.html

[243winxb]

Primer Chemicals

The chart below identifies the primer mix chemicals, the suppliers to ATK, and the country of origin. All 13 chemicals for primer mix are formulated by U.S.-based commercial companies, but 10 chemicals have origins outside of the United States. Of these 10 identified chemicals, 4 have origins solely in China, 2 others are only found in Mexico, and 1 is only found in Brazil. Three other chemicals share origins among the United States, European countries, India, China, and Mexico.

http://www.almc.army.mil/alog/issues...arms_ammo.html

[rodfac]

No difference in my experience when shooting off my bench or in the field. There is good evidence though, that real bench rest competitors do favor one kind over another. For gilt edged precision accuracy, and after a lot of experimentation, they'll make a difference.

BTW, Bart has a hellofa lot of experience in the competition fields. His recommendations are well worth your time.

Best Regards, Rod