how much does choice of primer affects accuracy?

[cpatbay]

In the list of things (powder type, powder weight, bullet choice, case type, etc), how much does the choice of primer affect accuracy? U am primarily in 223 reload at this time. And would be most interested in knowing if there is any significant benefit in using CCI #41 vs BR4.

[Cowboy T]

Depends on your gun and your load. If you've got, say, a very accurate .223 bolt gun, and you're good enough to consistently shoot half-inch groups at 100 yards, then yes, you may see some accuracy difference. I know one guy who shoots 300 RUM and is ticked off if he shoots bigger than one inch at 300 yds (that's a bad day for him--he's pretty good). Changing primers has affected his precision and aimpoint.

In handguns, it doesn't really matter so much because of the shorter distances typically involved.

[XDRoX]

Yep, if someone says that primers matter in a handgun, I'm not buying it.

But for precision bench shooting you want as much consistency as possible, so why not use the better primers?

[1lostinspace]

Everything matters

[cpatbay]

Yep, if someone says that primers matter in a handgun, I'm not buying it.

But for precision bench shooting you want as much consistency as possible, so why not use the better primers?

So, between CCI #41 and CCI BR4, which one is a "better" primer? Or are they more or less the same as far as better accuracy is concerned?

[John Browning]

So, between CCI #41 and CCI BR4, which one is a "better" primer? Or are they more or less the same as far as better accuracy is concerned?

All things being equal, a benchrest/match primer is always designed to be more accurate.

[thenodnarb]

I wouldn't go swapping magnum primers for standard primers, but I use them pretty interchangeably. If you have an accuracy load, I would stick with the same brand/type of primers for that load. Consistency in brand/type is more important than a particularly "better" primer. Now powder, thats a different story. My rifle likes some powders more than others, even at the same velocity.
maybe i'm just not good enough, or don't shoot enough to notice the difference in primers.

[Linkpimp]

[Linkpimp]

[Linkpimp]

MILSPEC PRIMERS FOR SEMI-AUTOS FAQ AND INFO

THERE IS A RE-OCCURING QUESTION AS TO WHICH PRIMER TO USE FOR RELOADING THE SKS, AK, AND OTHER MILITARY SEMI-AUTOS WITH FREE-FLOATING FIRING PINS.
THE FOLLOWING HAS BEEN REPRODUCED AS A SAFETY GUIDE.
Some rifles are much more susceptible to slam-fires than others. The SKS/AK are more susceptible than the AR15 and M1 Garand and M1A/M14, for example. Therefore, there is more 'forgiveness' built in to them as to primer selection. Another factor is rifle condition, parts tolerances, and cleanliness. A clean in-spec rifle is much more tolerant than one that isn't.
While one, with luck, may shoot a lifetime with standard commercial primers and a free-floating FP - IT IS STRONGLY RECOMMENDED THAT YOU HEED THE ADVICE OF EXPERTS IN CHOOSING YOUR PRIMERS AND THEN SEAT THEM PROPERLY BELOW THE SURFACE OF THE CASE BASE.

Another possibility is to have a MURRAY'S GUNSMITHING www.murraysguns.com spring-loaded firing pin installed in your SKS. This frees up your primer and ammunition choices.

The SPEER reloading manual is an excellent source of expert advice and states the following:

A slam-fire is the discharging of a cartridge in a firearm by the closing of the bolt without a pull of the trigger. In most cases this is a phenomenon associated with military-style semi-automatic rifles and handloaded ammunition. The slam-fire can be caused by a high primer or by a heavy, unsprung firing pin. High primers contribute to slam-fires because the closing bolt drives the high primer cup against the anvil. All handloads must be checked for high primers; this caution is even more important when shooting military-style semi-auto rifles.

Slam-fires have been reported even when primers were properly seated. Many semi-auto service rifles have no firing pin spring and the firing pin itself is quite heavy. The inertia of the firing pin may cause it to snap forward as the bolt stops, firing the cartridge. If the bolt is not yet fully locked, the result can be a ruptured case with the potential for gun damage and injury to the shooter. Military primers are less sensitive than commercial primers to minimize this hazard.
In 1994, CCI introduced the No. 34 [large rifle] and No. 41 [small rifle] primers for military semi-auto rifles... No. 34 primers are recommended for reloading 7.62mm NATO, 30-06 and 7.62x39 ammo for military semi-auto firearms.
No. 34 and No. 41 primers feature mil-spec sensitivity to minimize slam-fires. They are both fully DOD-qualified primers for use in U.S. military ammunition. However, no primer can provide 100% protection against slam-fires if the loader doesn't seat the primers deeply enough, or the rifle has a headspace problem or an out-of-spec firing pin.

PETER G. KOKALIS, noted military firearm author and expert, especially on select fire weapons, former Special Forces operator and combat veteran stated in the "Fighting Firearms" article on "Kalashniklones" the following:

I have fired tens of thousands of rounds through several hundred Kalashnikovs of every make and configuration [and one can assume extensive SKS experience as well]... Military issue Kalashnikovs and their semi-auto equivalents [and the SKS] do not have spring-loaded firing pins. If commercial or reloaded ammunition - usually with primers more sensitive than milspec because of a thinner cup and sometimes a difference in the primer mixture - is fired in rifles of this type, the free-floating firing pin can, and eventually will, result in a slam fire with ignition out of battery. The resulting detonation can lead to self-destruction of the firearm and anatomical damage of varying severity to the shooter... [going on to speak of the then-loaded Black Hills 7.62x39 ammo] Aware of this primer-sensitivity problem, Black Hills is using the CCI No. 34 milspec primer...

CMP U.S. RIFLE, CALIBER .30, M1 MANUAL
Manual delivered with a CMP Garand, Ammunition section paragraph 3:

...In most military semi-automatic rifles including the M1, the firing pin will lightly mark ("dimple") the primer of a cartridge as it is chambered when the bolt closes. Military ammunition has harder (less sensitive) primers than are usually found in commercial ammunition or available to handloaders [the CCI #34 excepted], and such dimpling is normally insufficient to fire a primer provided the receiver, bolt, firing pin and chamber conform to prescribed design dimensions. However, the use of non-military ammuntion with softer (more sensitive) primers reduces the margin of safety and requires the shooter to exercise greater caution. Conditions arising from excessive wear, out-of-specification parts or heavy chamber fouling that might pose no hazard with military cartridges could be dangerous with other ammunition.

RELOADING FOR THE M1 GARAND by KEN MARSH www.charm.net/~kmarsh/m1reload.html

3. Use a CCI mil-spec primer. These use primer cups that are harder than standard and help prevent slam-fires. Very important and often overlooked.
Avoid high primers, which cause slam-fires. Store ammo nose-down and look across the case heads, that allows you to quickly inspect 50 or more cartridges at once. Also run your fingertip over all primers as they come out of the press or priming tool.

RELOADING for the MATCH M14 by Glen D. Zediker www.zediker.com/downloads/14_loading.pdfhttps://www.sinclairintl.com/product...r-Pocket-Tools
Large Primer 8000 Uniformer - Item UN-8002

I hope the above information helps?

Have a great one

Link

[r3dn3ck]

linkpimp, update your username to datapimp. Title earned. Great reply and answered questions I didn't know I had. This coming from a fairly experienced reloader.

[Linkpimp]

[cpatbay]

Wow! What a wealth of useful information. I am glad I asked the question !

[Dave A]

Yes, another thank you from a fairly new reloader

[Fyathyrio]

Tons of info already posted, but here's one guy's results when doing a side by side comparison of a variety of powders and primers. They did make a difference for him.