I am now fully deployed into the 5.56 frenzy of black guns and brought my best friend along for the ride. We both bought S&W M&P15s and we have been long time reloaders. After much reading and info searching on the 5.56 NATO round we decided to go with CCI 41 primers as a hedge against "slam fire" issues, however they are hard to find in our area and a bit expensive at $46+ tax per 1k, when we can find them. I have heard that Wolf and Tula small rifle primers are hard and "probably" manufactured to milspecs. I know that they are less expensive. What primers do you use? and what's your backup?
Primer Hardness ?
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Magload
US Veteran
Win Small Rifle. Don
old&slow
Member
Oh NO ! the dreaded primer hardness discussion! 
I prefer Federal primers for most, if not all of my reloading.
Plus I don't shoot my AR that much, probably only a couple thousand rounds so far.
Never had a slam-fire,, yet..
But if I extract a chambered round you can see a little dimple on the primer where the firing pin marked it.. 
( edit, I'm using Federal SR match GM205M )
I prefer Federal primers for most, if not all of my reloading.
Plus I don't shoot my AR that much, probably only a couple thousand rounds so far.
Never had a slam-fire,, yet
.. But if I extract a chambered round you can see a little dimple on the primer where the firing pin marked it..
( edit, I'm using Federal SR match GM205M )
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Collo Rosso
Member
I've been using Tula and Wolf large and small standard primers for 223 in a AR and large standard primers for 308 in a M1a. No slam fires as of yet. They can be a bit of a pain to seat though. For back up I have boxes of Winchester and S&B but have yet to burn through the Russian stuff. I don't shoot a whole lot of rifle rounds.
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Classic29
Member
CCI 400's for plinking,read .223 pressures, CCI 450's for close to max loads. Never had a problem. Also tried Wolf and Remington 7 1/2 both gtg. Do not use Rem 6 1/2. They are soft and not made for .223/5.56 pressures.
for AR's, I use CCI #41 or the Tula .223 primers. A lot of guys on the highpower line will be shooting with Wolf or Tula .223 primers because a lot of people feel they give you match grade results. My only complaint with the Wolf or Tula primers is that they have a lot of primer residue all over them which gets all over your priming equipment especially the pickup tubes, so make sure you clean your gear of the green gunk.
old&slow
Member
So, half inch steel plate isn't harder to dent than quarter inch steel plate ,,, it's just thicker ..
( sorry, just had to do it
,, slow day around here today 
)BTW,, I really liked your chart, very interesting. Don't happen to have one for pistol primers do you ?
found the chart online somewhere long ago. white box CCI for AR didn't exist yet. never seen anything for handgun primers.
It is amazing how many millions of rounds were fired in AR's before "they" started to market military primers. Kinda like "tactical"
Manuals call for standard SR primers. How many slam fires have been seen using semi auto firing?
Manuals call for standard SR primers. How many slam fires have been seen using semi auto firing?
scooter123
Member
IMO the design of the bolt carrier in the AR15 is such that a slam fire can only result from exceptionally poor maintenance, so a military grade primer does make sense when you are actually in battlefield conditions where even rudimentary maintenance may not be possible. So, if I were loading ammunition for the US military I would be certain to use military primers. Since that isn't ever going to happen I'll keep using the easier to find CCI 400 primers and cleaning my rifles after every range outing.
Both the M14 and M16 had the firing pin lightened during their testing phase because of slam fires. These slam fires happened when loading a single round in the chamber without the magazine in position to slow down bolt velocity. No slam fires were mentioned when feeding from the magazine.
Remington ran Lake City Army Ammunition Plant from 1941 until 1985 and used the Remington 7 1/2 primer in all the 5.56 ammunition. And the 7 1/2 primer was used long before the CCI #41 and #34 primers were even thought about.
Bottom line it is recommended to use primers with a cup thickness of .025 in the AR15 rifle.
CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications
Small Rifle Standard
CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page
CCI BR4 - match primer with a thicker .025" cup.
Federal 205 - Mil-Spec cup thickness according to Federal - okay for 5.56mm. .0225" cup thickness.
Federal 205M - same as the 205 but the match version.
Magtech PR-SR - .025" cup thickness (not much feedback yet on this new primer as to AR15 suitability but with the same cup thickness as the Rem 7 1/2 it looks good so far)
Remington 6 ½ - thin .020" cup, intended for older, lower pressure rounds Remington says do not use for the .223 Rem or other similar pressure rounds. Good for .22 Hornet, .30 Carbine.
Remington 7 ½ BR - A match or "bench rest" primer. Lyman & Nosler classify this primer as a Standard. Remington says the compound is the same as the 6 1/2 but with a thicker .025" cup.
RWS 4033
Winchester WSR - some piercing issues noted when changed from silver to brass cup. Cup thickness is a bit thinner at .021". Most say they are good to go for the AR15 despite that, probably because of the hardness of the cup. Some feel they are less resistant to higher pressures.
Wolf/Tula Small Rifle SR #KVB-223 - soft, sensitive copper cup, not recommended for AR15/military rifle use or high pressure rounds.
Small Rifle Magnum
CCI 450 - same thicker .025" cup as the BR4 and #41.
CCI #41 - commercial version of the fully-qualified DOD primer for use in U.S. military ammo. With this primer there is more 'distance' between the tip of the anvil and the bottom of the cup than with other CCI SR primers. .025" thick cup. Same primer mix as CCI 450.
Remington 7 ½ BR - A match or "bench rest" primer. Hornady, Handloads.com, and Chuck Hawks classify this primer as a Magnum, differing from other sources that classify it as a Standard. .025" cup thickness.
Wolf/Tula Small Rifle Magnum SRM - hard, less sensitive brass cup intended for AR15/military rifle and high pressure rounds - #KVВ-5,56M.
Wolf/Tula Small Rifle 223 SR223 - #KVB-223M "This is the newest primer available in the Wolf line. It is ever so slightly hotter than the small rifle magnum primer and it comes with a brass colored thick cup. This primer can be used in place of the SRM primer or used when a different powder is used that is hard to ignite."
Now guess what primer I use for my AR15 rifles to light off harder to ignite Winchester ball powders.
The Remington 7 1/2 primer is also called "The Baby Flamethrower".
Remington ran Lake City Army Ammunition Plant from 1941 until 1985 and used the Remington 7 1/2 primer in all the 5.56 ammunition. And the 7 1/2 primer was used long before the CCI #41 and #34 primers were even thought about.
Bottom line it is recommended to use primers with a cup thickness of .025 in the AR15 rifle.
CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications
Small Rifle Standard
CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page
CCI BR4 - match primer with a thicker .025" cup.
Federal 205 - Mil-Spec cup thickness according to Federal - okay for 5.56mm. .0225" cup thickness.
Federal 205M - same as the 205 but the match version.
Magtech PR-SR - .025" cup thickness (not much feedback yet on this new primer as to AR15 suitability but with the same cup thickness as the Rem 7 1/2 it looks good so far)
Remington 6 ½ - thin .020" cup, intended for older, lower pressure rounds Remington says do not use for the .223 Rem or other similar pressure rounds. Good for .22 Hornet, .30 Carbine.
Remington 7 ½ BR - A match or "bench rest" primer. Lyman & Nosler classify this primer as a Standard. Remington says the compound is the same as the 6 1/2 but with a thicker .025" cup.
RWS 4033
Winchester WSR - some piercing issues noted when changed from silver to brass cup. Cup thickness is a bit thinner at .021". Most say they are good to go for the AR15 despite that, probably because of the hardness of the cup. Some feel they are less resistant to higher pressures.
Wolf/Tula Small Rifle SR #KVB-223 - soft, sensitive copper cup, not recommended for AR15/military rifle use or high pressure rounds.
Small Rifle Magnum
CCI 450 - same thicker .025" cup as the BR4 and #41.
CCI #41 - commercial version of the fully-qualified DOD primer for use in U.S. military ammo. With this primer there is more 'distance' between the tip of the anvil and the bottom of the cup than with other CCI SR primers. .025" thick cup. Same primer mix as CCI 450.
Remington 7 ½ BR - A match or "bench rest" primer. Hornady, Handloads.com, and Chuck Hawks classify this primer as a Magnum, differing from other sources that classify it as a Standard. .025" cup thickness.
Wolf/Tula Small Rifle Magnum SRM - hard, less sensitive brass cup intended for AR15/military rifle and high pressure rounds - #KVВ-5,56M.
Wolf/Tula Small Rifle 223 SR223 - #KVB-223M "This is the newest primer available in the Wolf line. It is ever so slightly hotter than the small rifle magnum primer and it comes with a brass colored thick cup. This primer can be used in place of the SRM primer or used when a different powder is used that is hard to ignite."
Now guess what primer I use for my AR15 rifles to light off harder to ignite Winchester ball powders.
The Remington 7 1/2 primer is also called "The Baby Flamethrower".
ArchAngelCD
Moderator, SWCA Member, Absent Comrade
I have used CCI#41, CCI-400, CCI-450, Rem 7 1/2 and Win SRP in AR 223 ammo and none have experienced slam-fire. I agree better safe than sorry so I now use CCI#41 primers but when not available I use CCI-450 instead followed but CCI-400.
Lockport Redhawk
Member
Good info here:
223 Rem + 223 AI Cartridge Guide
223 Rem + 223 AI Cartridge Guide
tndrfttom
Member
I’d recommend plain old Winchester Small Rifle Primers (WSR). I’ve used them in both my primary Service Rifle and back-up service rifle plus a carbine-style AR15. I can’t say how many rounds were loaded and fired but it was enough to need one service rifle barrel replaced. I did try Federal Bench Rest primers for a while for the 600 yd. Prone Slow Fire stage but couldn’t see that they improved my scores any. In any event I’ve never experienced a slam-fire in my rifles with Winchester WSR or Federal Bench Rest primers.
Magload
US Veteran
I use WSR for the loads in my AR15 bench rifle and as I do not use a magazine but use a Bob Sled. I just drop a round in the port and hit the release. If this doesn't cause a slam fire operating with a mag shouldn't. The rifle is in a forward and rear rest and petty much on target so a slam fire would not be a big thing. I use the WSR as that is about all you can get around here. Don
I've used most American primers for the AR and haven't had any failures or slam-fires.
If you are really concerned about slam-fires make triple sure where your muzzle is pointed before hitting that bolt release. Just one of the reasons the military uses clearing barrels.
If you are really concerned about slam-fires make triple sure where your muzzle is pointed before hitting that bolt release. Just one of the reasons the military uses clearing barrels.
I have come to believe that Remington primers are the hardest brand
overall simply because they always show smaller dimples than other
brands. In shooting Trap I have fired thousands of 12 ga Game or
Target loads and the primer dimples are tiny compared to other brands
but I have never experienced a misfire. Most of the factory Remington
ammo I have fired has been .380 caliber and the results are the same
as with 12 ga. Most of the Remington primers I have used in
handloads have been LP and they give good and consistant velocities
even though dimples are small. Maybe the priming compounds that
Remington uses are more sensitive.
overall simply because they always show smaller dimples than other
brands. In shooting Trap I have fired thousands of 12 ga Game or
Target loads and the primer dimples are tiny compared to other brands
but I have never experienced a misfire. Most of the factory Remington
ammo I have fired has been .380 caliber and the results are the same
as with 12 ga. Most of the Remington primers I have used in
handloads have been LP and they give good and consistant velocities
even though dimples are small. Maybe the priming compounds that
Remington uses are more sensitive.
Road_Clam
Member
I'll echo others as my experiences are that Win primers are a bit softer than the CCI's. I've had 2 primer piercings both was using Win primers. I also observe that CCI primers are just a tad tighter fitting than Win. So when I have very tight pockets I will use Win primers, and when i need need a tighter fitting primer (such as crappy FC brass) I use only CCI's.
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