With regards to long-range taking pictures, consistency is king – and rifle primers can play a important position in reaching it. A primer’s job is to ignite the powder cost, and the way persistently it does that instantly impacts muzzle velocity. Even slight variations in ignition can shift stress curves, resulting in velocity spreads that trigger vertical dispersion downrange.
The most effective rifle primers are manufactured with tighter tolerances, uniform priming compound, constant cup thickness, and dependable sensitivity. That stage of high quality delivers extra constant ignition from shot to shot, which interprets into decrease normal deviation (SD) and excessive unfold (ES) in velocity.
For shooters stretching past 600 yards (particularly 1,000+ yards), even small variations in velocity could cause important vertical POI shifts. In case your ammo has an SD of 15 fps, you would see 14-18 inches of vertical unfold at 1,000 yards – unacceptable in precision rifle competitions. A high quality primer helps decrease that variable, particularly when paired with high quality brass and constant powder prices.
Backside line: Should you’re chasing excessive precision, don’t overlook the significance of choosing the right rifle primer. It’s a small part of your load, however it will possibly have a huge impact on consistency and downrange efficiency.
So, what’s the finest rifle primer? Whereas everybody has an opinion, I surveyed the highest 200 ranked shooters within the Precision Rifle Collection (PRS) to see what rifle primer they have been utilizing of their match ammo. These guys signify the very best of the very best with regards to long-range rifle taking pictures, so getting perception from them is much better than listening to some random guys arguing on a discussion board! 
Let’s dive into the info! Here’s a take a look at the particular kind of primers that the highest 200 ranked marksmen within the PRS stated they have been working of their match ammo:
63% of those guys are utilizing CCI #450 Small Rifle Magnum Primers! CCI 450 primers are by far the most well-liked selection. That doesn’t shock me as a result of CCI #450s have been the most well-liked choice amongst professional shooters within the PRS for greater than 10 years. They’re identified to be extraordinarily constant, and there could also be one other profit to utilizing magnum rifle primers that I’ll share later on this article.
CCI BR-4 Small Rifle Primers have been tied for the 2nd hottest selection. It was utilized by 14% of those execs, and there have been extra high 10 shooters utilizing it than some other primer – though that was only one greater than the CCI #450 and the Federal 205M. The highest 10 appeared pretty evenly cut up among the many high 3.
Federal 205M Small Rifle Primers have been additionally tied for the 2nd hottest selection amongst this group of elite rivals, with a few the fellows within the high 10 working it as nicely.
91% of those shooters have been utilizing one of many primers above: CCI 450, CCI BR-4, or Federal 205M. These are clearly among the top-performing small rifle primers with regards to long-range precision. In case you are questioning what it’s best to strive in your match ammo, these are in all probability your finest bets. However there are a number of different varieties of primers represented amongst this group, and right here is the total checklist:
CCI #450 Small Rifle Magnum Primers
CCI BR-4 Small Rifle Primers
Federal 205M Small Rifle Primers
CCI #400 Small Rifle Primers
Federal 205 Small Rifle Primers
Federal 210M Giant Rifle Primers
Federal 210 Giant Rifle Primers
CCI BR-2 Giant Rifle Primers
CCI #41 Small Rifle Primers
What’s fascinating is that solely two primer manufacturers are represented amongst all 200 shooters: CCI and Federal. A decade in the past, CCI and Federal have been nonetheless the most well-liked, however we additionally noticed a number of of the highest shooters within the PRS utilizing TulAmmo, Winchester, Wolf, and Remington primers (view the info from 2015). It’s fascinating once you see consolidation like that over time, so I assumed it was value mentioning.
What Makes A Primer Benchrest or Match-Grade?
Many of those primers are marketed as “Benchrest” (BR) or “Match-Grade” (M) – however what does that even imply?!
I’ve heard every kind of hypothesis on this over time, however right here is the definitive reply from Jeff Siewart, a ballistic engineer with 40 years of business expertise. That is an excerpt from his guide Ammunition, Demystified:
“In response to sources at numerous primer manufacturing operations, once you purchase benchrest primers, what you’re spending your cash on is a barely bigger amount of primer combine, on common, than the usual primers and a barely tighter tolerance concerning combine weight variation. Dimensionally, there are not any variations within the metallic elements as a result of they’re made on the identical stamping traces as non-benchrest primers, utilizing the identical tooling.” – Jeff Siewart, Ballistic Engineer
Why Use Magnum Rifle Primers?
The most well-liked primer was the CCI #450 Small Rifle Magnum Primer. To be clear, none of those guys have been really utilizing magnum cartridges. They have been primarily utilizing medium-sized, short-action instances just like the 6mm Dasher, 6.5 Creedmoor, 6mm GT, 6mm BR, 25×47 Lapua, and different similar-sized instances. (View the info on what cartridges these professional shooters run)
So what’s the benefit of a magnum primer?
Within the guide Ammunition, Demystified, Jeff Siewart offers a radical technical rationalization of why magnum primers have been invented (pages 147-148), and it has to do with how trendy gun powders are made so as to present optimum efficiency. I’ll do my finest to summarize.
To get the absolute best precision and highest attainable muzzle velocity, you desire a rifle case to be filled with powder and for that powder to burn fully whereas the bullet remains to be within the barrel. Ideally, the height stress ought to happen farther down the bore, and the powder needs to be absolutely burned as near the chamber as attainable. That manner, increasing gases push on the bullet for so long as attainable with out losing vitality accelerating unburned powder that exits the muzzle (which additionally hurts accuracy).
Trendy powders obtain this stability utilizing deterrent coatings and particular grain shapes. Smaller grains with excessive ranges of deterrent coating burn slower on the floor however sooner total, serving to stretch out the stress curve and enhance velocity – which is nice for precision. However that additionally makes them tougher to ignite, particularly when the case is packed full, and also you’re taking pictures in chilly climate.
Magnum primers have been invented to unravel that ignition problem. They produce extra vitality initially, serving to to persistently ignite giant volumes of slow-burning, extremely deterred powder, lowering velocity spreads and stress inconsistencies.
Notice: I share a number of sensible tips about choosing the optimum rifle powder from Jeff’s guide on this article: Rifle Load Improvement: How To Discover The Greatest Powder & Load For Accuracy.
Now, is that the rationale the vast majority of these guys are working CCI #450 primers? I’m undecided. I can say the CCI #450 primers have confirmed to be very constant. A magnum primer could offer you a bit extra velocity than a normal primer, however the pattern among the many high shooters over the previous 3-4 years is to run their bullets at comparatively gradual velocities anyway. I’ll add that I’m personally one of many high 100 ranked PRS shooters from this previous 12 months, and I take advantage of CCI #450 primers in just about all of my match ammo that makes use of small rifle primers. I can attest that I get velocity SDs of 4-7 fps from my 6mm Dasher load, so I don’t see any purpose to alter it. That could be anecdotal, however I’d suspect most of those different professional shooters working it might say one thing comparable.
Small Rifle Primers vs. Giant Rifle Primers
You could have observed that the overwhelming majority of primers these guys use are small rifle primers, though a few of these instances, just like the 6.5 Creedmoor, have been initially designed for big rifle primers.
98% of those professional shooters use both match-grade brass made by Alpha Munition, Lapua, or Peterson (view knowledge on brass). All 3 of these brass producers supply a number of instances with the choice for primer pockets made for both a Giant Rifle Primer (LRP) or a Small Rifle Primer (SRP). The most well-liked instance is the 6.5 Creedmoor. The unique 6.5 Creedmoor case design from Hornady had a big rifle primer, however Alpha, Lapua, and Peterson are all providing 6.5 Creedmoor instances with a small rifle primer OR a bigger rifle primer. They may additionally supply instances with the choice for small or giant primers in 22 Creedmoor, 6XC, 6mm Creedmoor, 25 Creedmoor, 260 Rem, 308 Win, and different instances.
I used to be curious what number of of those top-ranked shooters opted for one primer or the opposite, so I did some evaluation on it – and it’s fairly conclusive!
98% of those guys have been working brass with small rifle primers! Solely 3 folks have been working giant rifle primers, and none of these have been inside the highest 100. In truth, 2 of these utilizing a big primer have been taking pictures a 308 Win within the tactical division (however nonetheless shot nicely sufficient to complete within the highest 200 within the PRS Open Division). So, in the event you have been questioning if you should purchase the brass with a small rifle primer pocket or giant – this group appears fairly definitive on that!
I’ll add that I’ve heard ballisticians from Hornady say that in case you are utilizing a Creedmoor-sized case in chilly circumstances (under freezing), they might extremely suggest a big rifle primer. They are saying you would expertise ignition issues attempting to mild powder in these instances which have over 35 grains of powder with a small rifle primer.
“Sadly, you see an enormous push to the small primer pocket brass for match taking pictures in sure cartridges, just like the Creedmoor household. We’ve seen fairly a little bit of that obtainable. What quite a lot of guys don’t perceive is that you just’re skirting the road there with the mix of the cost weights which might be used inside these cartridges, the kind of propellant that’s used, after which the small rifle primer that at typically at colder temperatures you’ll be able to have ignition associated points with these. In order that’s one thing to remember. A small primer pocket isn’t simply extra materials across the primer pocket, that means you’ll be able to stand on pressures, and your brass lasts longer. There are different issues happening as nicely.” – Jayden Quinlan, Hornady Senior Ballistician
I personally competed with a 6mm Creedmoor for five+ years and simply fired 10,000+ rounds with a small rifle primer in it and not using a single ignition subject – however only a few of these rounds have been fired under freezing. I used to be utilizing CCI #450s and Hodgdon H4350. The blokes at Hornady are specialists, and that’s solely my anecdotal expertise – however I simply need to attempt to current a balanced view.
“It will get muddy as a result of there are occasions the place it’s like this primer works with, say, all 5 of those cartridges it doesn’t matter what powder you set in it. Then you definately change to this different powder in those self same 5 cartridges, and for 3 you higher use this primer, and for these two you higher use a special primer, as a result of in the event you don’t do this, then issues are coming.” – Jayden Quinlan, Hornady Senior Ballistician
I’ve additionally heard Jayden say that within the analysis they’ve executed at Hornady, they’ve discovered no precision or consistency benefit to small rifle primers. He additionally hadn’t heard of some other severe analysis that had been executed by different labs that may point out some intrinsic profit with regards to small rifle primers for precision.
One purpose many of those shooters go for small rifle primers is the idea that extra materials on the base of the case across the primer pocket might both prolong brass life or probably assist barely greater pressures. I’d additionally wager that some folks do consider that small rifle primers are doubtlessly extra constant and would possibly assist precision. However, once more, I haven’t seen any severe analysis (based mostly on applicable giant pattern sizes) that helps that conclusion. So I can’t affirm or deny that.
If anybody is conscious of analysis into small rifle primers vs giant rifle primers, please share it with us within the feedback!
Coming Up Subsequent
This text is a part of a collection on rifle reloading knowledge, load improvement, and reloading elements. Listed below are different associated articles that I’ve just lately printed or plan to publish within the close to future:
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