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Well, Ok then dude.

Here's some more for you, but likely you don't need or heed any more outside info.

MM


CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS

Based on an article by John Barsness - GUNS magazine pg 26 May 2009. [JB, formerly of Handloader is one of the most qualified gunwriters when it comes to primers and reloading in general]
Information from the Speer #14, Hornady #7, Nosler#6, and Lyman #49 reloading manuals, Alliant and Accurate Arms data.

CUP THICKNESS

Different primers have different cup thicknesses. You can see the importance of cup thickness when primers are considered for semiautomatic rifles that have free-floating firing pins. This topic is discussed in greater detail in the post "MILSPEC PRIMERS FOR SEMI-AUTOS FAQ AND INFO" that follows the primer chart.

Handgun primers have thinner cups than rifle primers, making them easier to ignite with the typically weaker firing pin fall of handguns. Small Pistol primer cups are .017" thick, while Large Pistol primer cups are .020" thick. This is the reason using handgun primers in .22 Hornet rifle loads sometimes results in pierced primers in some guns. Obviously their substitution in the high pressure .223 Remington would not be a good idea.

Even the same type of primers from different manufacturers can have different cup thickness. Federal primers tend to have thinner cups than Winchester, Remington and CCI primers. On occasion this can be handy. Some revolver trigger and action lightening jobs may result in a lighter hammer fall that results in not all the primers going off. A switch to Federal pistol primers can make the load 100% again. The same thing can happen in cold weather with some “modern” bolt actions with light, fast firing pins. These are supposed to whack primers with the same approximate energy as an old-fashioned 98 Mauser strike, but under some adverse conditions they can occasionally use a little help. Federal primers can provide that help.
With Remington small rifle primers, the 6 ½ primer has a thin cup and is not recommended for higher pressure rounds like the common .223 Remington. It was intended for the .22 Hornet. When Remington introduced their .17 Remington round in 1971 they found that the 6 ½ primer was not suitable to the high-pressure .17. The 7 ½ BR primer was developed for this reason. According to Remington, the 7 ½ has a 25% greater cup thickness and they state on their web site: "In rifle cartridges, the 6-1/2 small rifle primer should not be used in the 17 Remington, 222 Remington or the 223 Remington. The 7-1/2 BR is the proper small rifle primer for these rounds."
CCI/Speer Technical Services says: "The CCI 400 primer does have a thinner cup bottom than CCI 450, #41 or BR4 primers... [with] the CCI #41 primer... there is more 'distance' between the tip of the anvil and the bottom of the cup." so that is their AR15 recommendation, although it seems like there are no complaints with using the BR4 and 450 primers by AR15 shooters and reloaders, in general. The #41 just gives you a little more safety margin for free-floating firing pins and would be the best choice for commercial reloaders who have no control over the rifles their .223 ammo is used in.

Another factor which determines the strength of a primer cup is the work hardened state of the brass used to make the primer cup. They are made with cartridge brass (70% copper, 30% zinc), which can vary from 46,000 psi, soft, to 76,000 psi tensile strength when fully hardened. Manufacturers specify to their brass suppliers the hardness of brass desired. It is possible that a primer manufacturer could choose a harder brass in order to keep material thickness down and reduce costs. Winchester WSR primers are somewhat thin, yet seem to be resistant to slam-fires and this is likely due to this hardness factor.

Large rifle primers all appear to have the same cup thickness of .027", no matter what the type.

This also affects pressure tolerance. Cases that utilize small rifle primers and operate at moderate pressures(40,000 psi) should use CCI 400, Federal 200, Rem 6 1/2, or Win WSR. Such cases include 22 CCM, 22 Hornet and the 218 Bee. These primers can also used in handguns such as the 9mm., 357, etc. Other cases that use the small rifle primer can use the above primers only if moderate loads are used. Keep to the lower end of reloading recommendations.
Cases that utilize Small Rifle primers and operate at higher pressures (55,000 psi) should use CCI 450, CCI BR4, Fed 205 and Rem 7 1/2 etc.

PRIMER CHART & REFERENCE GUIDE

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. T

This primer can be used in place of the SRM primer or used when a different powder is used that is hard to ignite."

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.

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/Tula SRM (QQQSRM or KVВ-5,56M) 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/Tula 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/TULA 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/Tula Small Rifle 223 SR223 "This is the newest primer available in the Wolf/Tula 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."

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/Tula SRM
Wolf/Tula SR223