Originally Posted By: SDCoyoteCallerI asked a similar question awhile back and this is the responses I got. There is a handy chart in there regarding cup thickness that is beneficial. I have settled on the Rem 7 1/2s.
http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=1608839
I went to your link and read it. Good read and in my pee picken little brain it makes very good sense to do all you can to minimize a chance of a slam fire.
Here is what was printed.
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.pdf
Loading bench slam fire cures are primarily primers. First is choice. LC ammunition has a tough primer. The only commercially available primer I know of that’s similar in construction is the tough skinned WW®. CCI® is hard aplenty too. There is greater insurance against a slam fire using either of these primers. The one that, I say (as well as did every single gunsmith I’ve asked) not to use is Federal ®. It’s “touchier.” Remington® is okay, but not a positive step (in this direction). That’s too bad because the Federal® can work well with other .308 W. loads. Honestly, it’s a risk on an M14.
Primers recommended for use in .308 Win/7.62x51/7.62x39 semiautomatic rifle loads:
CCI #34, 200, BR2, CCI 250
Winchester WLR, WLRM
Wolf LR
################################################## ########################################
SMALL RIFLE (.223/5.56) PRIMERS?
The .223 Remington or 5.56mm NATO round is commonly found in semiautomatic rifles and also has special primer considerations using Small Rifle-size primers. Some recommendations follow:
Primers used for .223 Rem. loads should have heavy cups to resist perforation at the high pressures normal for this round. Military 5.56mm primers have a cup thickness of about 0.24", compared to .020" or so that was traditional for the standard small rifle primers. Federal 205, 205M, Remington 7 1/2 BR, Winchester WSR, and CCI BR4, 450, #41, and Wolf SRM (QQQSRM) primers have cups of about the same thickness as military primers, and are the best to use when reloading the .223.
The Remington 6 1/2 and 7 1/2 are essentially the same. The 7 1/2 cup metal is thicker so that the primer can stand up to higher pressures... cup thickness is 25 percent greater... BRIAN PEARCE (quoting Remington), Pg. 14, HANDLOADER, October 2006.
The Remington 7 1/2 BR primer was developed for the hot, high-pressure 4100 fps. .17 Remington round and also used in .223 loads. When Freedom Arms transitioned the .454 Casull case to use the small primer, they picked the Rem. 7 1/2 BR because it gave reliable ignition and easily withstood the 65,000 psi generated by the hot pistol round. It is highly recommended for .223 AR15-type loads.
CCI states: "The CCI 400 primer does have a thinner cup bottom than CCI 450, #41 or BR4 primers. The appropriate primer for an AR15 platform is the CCI #41 primer, which helps to prevent slamfires. With this primer there is more 'distance' between the tip of the anvil and the bottom of the cup." [as per: Linda Olin - CCI/Speer Technical Services]. Despite this, it seems that most AR15 reloaders have experienced no problems using the BR4 and 450 thicker cupped primers in rifles in good condition. The #41 gives the greatest safety margin however.
The experts at 6mmBR.com have this to say about AR15 primer choice:
For use in semi-automatics and AR15s, we advise that you stick to CCI and Remington primers. These brands have harder cups and are much less likely to pierce primers. Also, the AR15 has a free-floating firing pin that dents the primer on loading. This creates a risk of slam fires. So you want hard primer cups. The latest generation of Winchester primers, with brass-colored cups, should be avoided for AR15 use. The old silver Winchester primers worked fine, but the current WSRs are soft and can be pierced more easily than CCI or Rem primers. A poll of Highpower competitors (mostly shooting ARs) showed that Rem 7 1/2 primers are the most popular (33.23%), followed by CCIs (25.78%). The majority of CCI users favored the CCI BR4s, but both CCI 400s (small rifle standard) and CCI 450s (small rifle magnum) were also popular. Only 10.25% of Highpower shooters polled used Federal primers (either 205M or 205). At the time of the poll, many shooters reported using WSRs, but this was the older version with silver cups.
Wolf also makes two small rifle primers that are suitable for 5.56 loading. First is their Small Rifle Magnum SRM primer (not the Standard). They have this to say: "If you are loading for an AR15 or Military Style semi auto rifle, or are loading high pressure cartridges in any other type of rifle ,we recommend you use the Magnum Small rifle primers. Both primers use the same amount of compound. The only difference is in the cup hardness. The WOLF Standard Small Rifle Primers have an all COPPER CUP, which is a little more sensitive than the brass cup magnum primers." Second is their newer Wolf Small Rifle 223 SR223 "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." There is no mention, as far as I can find, about how hard their Large Rifle primers are.
Primers recommended for use in .223 Rem/5.56 semiautomatic rifle loads:
CCI #41, 450, BR4
Federal 205, 205M
Remington 7 1/2 BR
Winchester WSR
Wolf SRM
Wolf SR223
PRIMER SEATING DEPTH AIDS
Uniforming primer pockets about guarantees no primer sitting flush with or above the plane of the case head, which won’t guarantee no chance of a slam fire, but it won’t hurt. A uniformed pocket is assurance of consistent and adequate depth to get the primer the necessary 0.004 or more under the plane of the case head (0.008 isn’t too much). Use a primer pocket uniforming tool in place of a primer pocket cleaner. Next step is making sure they’re under the head. Run a finger across them; don’t just look. Primers have a beveled edge so can look (around the edges) like they’re seated below flush when the center of the primer is not. Believe it or not, your finger is extremely sensitive and accurate for feeling that the primer is below flush and is as accurate as a mechanical measure for the issue.
If proper primer seating depth is an issue with the batch of cases that you are using, SINCLAIR INTERNATIONAL carries Primer Pocket Uniformers that can be chucked in a drill and used to uniform the primer pocket to a standard SAAMI depth and flat bottom for optimum primer seating or match prepping cases. I personally use them and consider these tough carbide-steel tools to be one of the better gadgets on my reloading bench. http://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
linkpimp is offline Reply With Quote
Old 10-21-2011
There is such thing as a slam fire as I have had one and only one and to my chagrin it was my fault.
I had just bought 500 new Winchester .223 Remington brass and when I reloaded the first 50 or so and I did not run my finger across the bottom of the case after I primed them like I normally do . I had shot a few, don't remember how many and pulled the trigger and two rounds went off with one pull of the trigger. I consider my self real lucky as the bolt was locked up enough that no harm was done to me or the AR I was shooting. I was shocked to say the least. when I examined both cases I found that the one and supposed it was the one that went off with out a trigger pull as the it had a high primer . I checked the rest of the rounds I had and there was one more that had a high primer. Packed up went home and pulled the bullet and emptied the powder out of the other round that I found with a high primer, tried to seat the primer to the proper depth but it would not budge. I deprimed and measured the primer pocket and found it was way under depth. I was using CCI 450's.
I have since bought a Sinclair primer pocket uniformer and all my brass gets the primer pocket redone. whether it is for the AR or my 300 Win Mag. the nice thing is you only have to do it once.
Have shot many a round through the AR since the incident with nary a hick up.
You all use the primer you want , but for me I'll stick to the CCI450's and rework every primer pocket in all my brass.And yes I will not forget to check each primer with my finger after seating.
Remember this it only takes one slam fire to ruin your day no matter what the cause is.
DAB
http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=1608839
I went to your link and read it. Good read and in my pee picken little brain it makes very good sense to do all you can to minimize a chance of a slam fire.
Here is what was printed.
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.pdf
Loading bench slam fire cures are primarily primers. First is choice. LC ammunition has a tough primer. The only commercially available primer I know of that’s similar in construction is the tough skinned WW®. CCI® is hard aplenty too. There is greater insurance against a slam fire using either of these primers. The one that, I say (as well as did every single gunsmith I’ve asked) not to use is Federal ®. It’s “touchier.” Remington® is okay, but not a positive step (in this direction). That’s too bad because the Federal® can work well with other .308 W. loads. Honestly, it’s a risk on an M14.
Primers recommended for use in .308 Win/7.62x51/7.62x39 semiautomatic rifle loads:
CCI #34, 200, BR2, CCI 250
Winchester WLR, WLRM
Wolf LR
################################################## ########################################
SMALL RIFLE (.223/5.56) PRIMERS?
The .223 Remington or 5.56mm NATO round is commonly found in semiautomatic rifles and also has special primer considerations using Small Rifle-size primers. Some recommendations follow:
Primers used for .223 Rem. loads should have heavy cups to resist perforation at the high pressures normal for this round. Military 5.56mm primers have a cup thickness of about 0.24", compared to .020" or so that was traditional for the standard small rifle primers. Federal 205, 205M, Remington 7 1/2 BR, Winchester WSR, and CCI BR4, 450, #41, and Wolf SRM (QQQSRM) primers have cups of about the same thickness as military primers, and are the best to use when reloading the .223.
The Remington 6 1/2 and 7 1/2 are essentially the same. The 7 1/2 cup metal is thicker so that the primer can stand up to higher pressures... cup thickness is 25 percent greater... BRIAN PEARCE (quoting Remington), Pg. 14, HANDLOADER, October 2006.
The Remington 7 1/2 BR primer was developed for the hot, high-pressure 4100 fps. .17 Remington round and also used in .223 loads. When Freedom Arms transitioned the .454 Casull case to use the small primer, they picked the Rem. 7 1/2 BR because it gave reliable ignition and easily withstood the 65,000 psi generated by the hot pistol round. It is highly recommended for .223 AR15-type loads.
CCI states: "The CCI 400 primer does have a thinner cup bottom than CCI 450, #41 or BR4 primers. The appropriate primer for an AR15 platform is the CCI #41 primer, which helps to prevent slamfires. With this primer there is more 'distance' between the tip of the anvil and the bottom of the cup." [as per: Linda Olin - CCI/Speer Technical Services]. Despite this, it seems that most AR15 reloaders have experienced no problems using the BR4 and 450 thicker cupped primers in rifles in good condition. The #41 gives the greatest safety margin however.
The experts at 6mmBR.com have this to say about AR15 primer choice:
For use in semi-automatics and AR15s, we advise that you stick to CCI and Remington primers. These brands have harder cups and are much less likely to pierce primers. Also, the AR15 has a free-floating firing pin that dents the primer on loading. This creates a risk of slam fires. So you want hard primer cups. The latest generation of Winchester primers, with brass-colored cups, should be avoided for AR15 use. The old silver Winchester primers worked fine, but the current WSRs are soft and can be pierced more easily than CCI or Rem primers. A poll of Highpower competitors (mostly shooting ARs) showed that Rem 7 1/2 primers are the most popular (33.23%), followed by CCIs (25.78%). The majority of CCI users favored the CCI BR4s, but both CCI 400s (small rifle standard) and CCI 450s (small rifle magnum) were also popular. Only 10.25% of Highpower shooters polled used Federal primers (either 205M or 205). At the time of the poll, many shooters reported using WSRs, but this was the older version with silver cups.
Wolf also makes two small rifle primers that are suitable for 5.56 loading. First is their Small Rifle Magnum SRM primer (not the Standard). They have this to say: "If you are loading for an AR15 or Military Style semi auto rifle, or are loading high pressure cartridges in any other type of rifle ,we recommend you use the Magnum Small rifle primers. Both primers use the same amount of compound. The only difference is in the cup hardness. The WOLF Standard Small Rifle Primers have an all COPPER CUP, which is a little more sensitive than the brass cup magnum primers." Second is their newer Wolf Small Rifle 223 SR223 "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." There is no mention, as far as I can find, about how hard their Large Rifle primers are.
Primers recommended for use in .223 Rem/5.56 semiautomatic rifle loads:
CCI #41, 450, BR4
Federal 205, 205M
Remington 7 1/2 BR
Winchester WSR
Wolf SRM
Wolf SR223
PRIMER SEATING DEPTH AIDS
Uniforming primer pockets about guarantees no primer sitting flush with or above the plane of the case head, which won’t guarantee no chance of a slam fire, but it won’t hurt. A uniformed pocket is assurance of consistent and adequate depth to get the primer the necessary 0.004 or more under the plane of the case head (0.008 isn’t too much). Use a primer pocket uniforming tool in place of a primer pocket cleaner. Next step is making sure they’re under the head. Run a finger across them; don’t just look. Primers have a beveled edge so can look (around the edges) like they’re seated below flush when the center of the primer is not. Believe it or not, your finger is extremely sensitive and accurate for feeling that the primer is below flush and is as accurate as a mechanical measure for the issue.
If proper primer seating depth is an issue with the batch of cases that you are using, SINCLAIR INTERNATIONAL carries Primer Pocket Uniformers that can be chucked in a drill and used to uniform the primer pocket to a standard SAAMI depth and flat bottom for optimum primer seating or match prepping cases. I personally use them and consider these tough carbide-steel tools to be one of the better gadgets on my reloading bench. http://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
linkpimp is offline Reply With Quote
Old 10-21-2011
There is such thing as a slam fire as I have had one and only one and to my chagrin it was my fault.
I had just bought 500 new Winchester .223 Remington brass and when I reloaded the first 50 or so and I did not run my finger across the bottom of the case after I primed them like I normally do . I had shot a few, don't remember how many and pulled the trigger and two rounds went off with one pull of the trigger. I consider my self real lucky as the bolt was locked up enough that no harm was done to me or the AR I was shooting. I was shocked to say the least. when I examined both cases I found that the one and supposed it was the one that went off with out a trigger pull as the it had a high primer . I checked the rest of the rounds I had and there was one more that had a high primer. Packed up went home and pulled the bullet and emptied the powder out of the other round that I found with a high primer, tried to seat the primer to the proper depth but it would not budge. I deprimed and measured the primer pocket and found it was way under depth. I was using CCI 450's.
I have since bought a Sinclair primer pocket uniformer and all my brass gets the primer pocket redone. whether it is for the AR or my 300 Win Mag. the nice thing is you only have to do it once.
Have shot many a round through the AR since the incident with nary a hick up.
You all use the primer you want , but for me I'll stick to the CCI450's and rework every primer pocket in all my brass.And yes I will not forget to check each primer with my finger after seating.
Remember this it only takes one slam fire to ruin your day no matter what the cause is.
DAB
