There has been discussion of slam fires in gas guns when reloading using Federal Small Rifle primers. Apparently, CCI makes a primer specifically for the AR platform that negates the slam fire. Please discuss.
Federal small rifle primer slam fires
- Thread starter bluto77
- Start date
Has this happened to you or are you just wondering?
I've heard the theory of slam fires with ARs, but never actually seen it happen or know of anyone that's had it happen to. The only exception is when a guy tried small pistol primers in .223 ammo and did get a few slam fires, but he was experimenting and expected it.
I use regular Winchester small rifle and Remington 7 1/2 primers for .223 and standard Win LR primers for the big autos. I've never used Federals, so can't help there. I've always thought of the 5.56 primers as marketing hype. I wonder what primers Federal uses in their ammo?
I've heard the theory of slam fires with ARs, but never actually seen it happen or know of anyone that's had it happen to. The only exception is when a guy tried small pistol primers in .223 ammo and did get a few slam fires, but he was experimenting and expected it.
I use regular Winchester small rifle and Remington 7 1/2 primers for .223 and standard Win LR primers for the big autos. I've never used Federals, so can't help there. I've always thought of the 5.56 primers as marketing hype. I wonder what primers Federal uses in their ammo?
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Several companies (CCI and Federal to name two) are marketing AR-specific primers now because of perceived (and some actual) issues with standard primers in weapons that have free-floating firing pins. Basically, especially re: Federal, some of their primers have a reputation for having softer/thinner primer cups. As a result, it is POSSIBLE (not a regular occurrence by any means) to get an AD/slam fire when using those primers. The Federal Gold Medal Match AR Primers, and those offerings from CCI mentioned above, are small rifle match primers that are optimized for ARs and similar semi-automatic firearms because they feature harder primer cups than some other primers that get used regularly in commercial ammo. Nothing whiz-bang about the design...just slightly modified to offer "more reliable" (wink, wink) performance in semis. (INSERT MR. MARKETING COMMENTS HERE 
).
Here is some info I have posted in the past on this issue:
If you get a soft primer, or if you chamber a round that has been chambered (but not fired) and ejected several times, the likelihood of a slam fire increases.
The other part of the lesson on slamfires with ARs is: 1) maintain a clean, well-lubed weapon, including insuring there is no crud or debris causing the pin to protrude any which ups the chances of a slamfire; and 2) be wary of the primer being used with the rounds you are using, especially if reloading (i.e. - federal are softer than say CCI, etc., etc.). ...The following is a link to a compilation of a couple different sources about primers that you may find useful:
Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications
There are numerous resources concerning primers being "soft" or otherwise having "thinner" cups than others. Just be advised, especially if you are reloading, that not ALL primers were created equally.
).Here is some info I have posted in the past on this issue:
If you get a soft primer, or if you chamber a round that has been chambered (but not fired) and ejected several times, the likelihood of a slam fire increases.
The other part of the lesson on slamfires with ARs is: 1) maintain a clean, well-lubed weapon, including insuring there is no crud or debris causing the pin to protrude any which ups the chances of a slamfire; and 2) be wary of the primer being used with the rounds you are using, especially if reloading (i.e. - federal are softer than say CCI, etc., etc.). ...The following is a link to a compilation of a couple different sources about primers that you may find useful:
Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications
There are numerous resources concerning primers being "soft" or otherwise having "thinner" cups than others. Just be advised, especially if you are reloading, that not ALL primers were created equally.
Also take in to account that the harder primers may not work with lite trigger springs /some triggers. Surplus ammo will not work with all aftermarket triggers do to their primers.
I've had it happen a couple times, but once was in my 10mm auto, so that doesn't count, the other was a .300 blk with hand loads and quite possibly could have had a pistol primer sneak into the mix. If it's a big deal (it's not) cut a bolt release spring in half. Remove firing pin and slide the spring over the firing pin, then reinstall it. That will eliminate slamfires. But I don't think it's an issue in the least.
It was referenced in another thread when I brought up starting to load for my Wylde chambered 5.56/.223. I'm new to reloading, and I had never heard of it. It seemed like the jury was still out on it being an issue or a non-issue and more of a marketing hype. Are the specialized AR primers more expensive or something? It seems like if it has happened to people, even if it doesn't happen all the time, and there are primers designed to prevent the slam fire from occurring, then why not just be safe and use those, unless of course, they're considerably more expensive or harder to find.
You do NOT have to buy the "AR-specific" primers by any means, but...as with all things...be aware that not all primers are well-suited for use in semi-auto firearms that have free-floating firing pins. There are PLENTY of "standard" primers that will run 100% in ARs and like firearms with very low safety concerns relating to slam-fires. If you are sold by the marketing of "AR-specific" primers...then have at them. The prices on them aren't what I'd call "considerably" more expensive...but they do carry a premium in terms of price (i.e. - the Federal AR match primers run ~$200/5k while other "standard" primers that are known to perform well/safely in semis can be had for up to 25% less give or take...similarly, the CCI 41 primers which are mil-spec, purposefully designed to deal with slam-fire issues in 5.56 weapons run ~$190/5k). As for the "availability" argument...primers aren't exactly plentiful right now, but they can still be had...just depends on whether you are stuck buying locally and living with what's on the shelves or you can scrounge the interweb for deals and live with the hassle of HAZMAT S&H.
Only you can decide what your comfort level is with respect to primer choice/selection, but paying a 25% premium is NOT necessary for safe/efficient operation when reloading for any AR. Read the lengthy post in the link I provided in my post above...especially the portions re: primer selection and reloading for 5.56/.223 ARs, then make your decision based on what you glean from the article and what you believe from a marketing standpoint and buy accordingly.
A lot of slam fires are caused by guys trying to top load a semi-auto. Countless rounds have been sent down range using regular non-"mil spec" CCI primers with zero issues. If you reload the cartridge correctly to begin with and don't do things that are known issues like top-loading then you shouldn't have any issues. I still stand by my opinion though that someone is full of shit if they think a slam fire will ruin a gun.
This is not a new phenomenon... more than 20 years ago, I was advised by folks that know WAY better than me (even now with 20 years more experience), that Federal primers are SOFT, and you do NOT use them in an auto-loader with floating firing pin... At that time, we were discussing the M1A I had just gotten to compete in Highpower. Same thing applies to the AR, the firing pin is just a little lighter.
All other brands I'm aware of have harder cup material, and don't have that problem in the AR.
All other brands I'm aware of have harder cup material, and don't have that problem in the AR.
One more point of information.
Gary Roberts has reported that repeated chambering of Hornady TAP in an AR can desensitize/otherwise prevent primer ignition.
This was observed when a certain LE agency team experienced a click instead of a bang during an entry. They tested the rest of their ammunition and found one additional malfunction. It was later discovered team members were re-chambering rounds (big no-no).
I don't know of the same occurrence with other manufacturers, but it's yet another reason not to re-chamber rounds more than once.s
I don't remember the external link posting rules right damn now, but I can send you a link to his comments and details if needed.
Gary Roberts has reported that repeated chambering of Hornady TAP in an AR can desensitize/otherwise prevent primer ignition.
This was observed when a certain LE agency team experienced a click instead of a bang during an entry. They tested the rest of their ammunition and found one additional malfunction. It was later discovered team members were re-chambering rounds (big no-no).
I don't know of the same occurrence with other manufacturers, but it's yet another reason not to re-chamber rounds more than once.s
I don't remember the external link posting rules right damn now, but I can send you a link to his comments and details if needed.
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I didn't know you weren't supposed to ever re-chamber a round. When we're hunting I put one in the chamber, and when we get back to the camp house I remove the unfired round from the chamber and put it back in the magazine. It will be the round on the top of the mag, so that one may get re-chambered at least a few times before it ever gets fired. Is this a big no-no for hand loaded ammo only? Damn....I feel like a dumb-ass asking these questions.
I've reloaded and shot, literally, tens of thousands of rounds of home-made .223/5.56 rounds out of AR15 and M16 platforms using CCI, winchester, Federal primers and never had a slam-fire. Ditto several thousand 7.62 rounds.
Had a LOT of slam-fires with a cheap SKS back in the 90s (I sold that ASAP) and most recently in an M1 carbine (solved by new springs and a thorough cleaning). Not shooting reloads, either, but factory ammo.
I've heard of this happening with reloads, like I've heard of bullets getting STUCK when shooting subsonics from 26 inch barrels but I've never experienced it.
Not saying it doesn't happen, or can't happen, but not in my experience.
Had a LOT of slam-fires with a cheap SKS back in the 90s (I sold that ASAP) and most recently in an M1 carbine (solved by new springs and a thorough cleaning). Not shooting reloads, either, but factory ammo.
I've heard of this happening with reloads, like I've heard of bullets getting STUCK when shooting subsonics from 26 inch barrels but I've never experienced it.
Not saying it doesn't happen, or can't happen, but not in my experience.
The primers I've used the majority of the time to reload for an M1A have been Federal 210M primers and I've never had a problem with them.
There are closed bolt and open bolt slam fires. Closed bolt is no big deal unless the gun is pointed the wrong way but open bolt is entirely different. I had a bunch of closed bolt slam fires in an M1 Garand which as far as I can tell came from not using a small base die to resize once fired brass. It happened with a variety of primers including mil spec primers.
I believe that the majority of the time it doesn't matter what primer you use but there are exceptions.
There are closed bolt and open bolt slam fires. Closed bolt is no big deal unless the gun is pointed the wrong way but open bolt is entirely different. I had a bunch of closed bolt slam fires in an M1 Garand which as far as I can tell came from not using a small base die to resize once fired brass. It happened with a variety of primers including mil spec primers.
I believe that the majority of the time it doesn't matter what primer you use but there are exceptions.
I've used Federal primers for years. They are softer than others but the problem I see more is Federal primers not fitting in LC brass as readily as CCI primers because some LC primer pockets are smaller compared to say Winchester brass.
Slam fire? Never happened to me.
Slam fire? Never happened to me.
One thing missing from this discussion is primer seating depth, failure to properly seat the primer (high seating) is going to be the cause the vast majority of the slam fires. Poor seating in a good primer pocket, or poor seating due to a dirty primer pocket. In either case, the likelihood of a slam fire is far greater than a "soft" cup and a floating firing pin. Even on a M1a/M14 when properly loaded (weapon in spec) 100,000s of 205 have been loaded with exceptional results. One other point of interest, the "mil spec" small rifle primers are harder, but also of magnum strength. If you are going to switch to a "mil spec" small rifle primer, and you've done all your load data with a standard primer, be prepared for load adjustment from the "get go".
I've used nothing but federal and cci and load for ARs, M1As and Garands almost exclusively and have never had a problem. To me it's just hysteria from way back in the day when there actually was such a thing as a soft primer because nobody loaded for semis, just bolts...semis are common now and as a result every company makes their primers 'okay' for semi-auto use.
Very good points. primer seating depth is a more important piece of information than what primer you are using in an ar15.
If you're not riding the bolt forward there's a couple things I've heard CAN happen from rechambering multiple times, the one I've part way witnessed is the firing pin indent progressively deepening, word is it can creep up into contact with the anvil and without any air gap may not ignite, the other is that the repeated sudden stop can jar the anvil loose. I suspect it takes a great number of cycles normally, its up to you to decide whether or not the odds are worth it.
This might have been an issue, maybe, with some of the older WW2 rifles,,,, but i dont think its an issue with a modern AR. The most important thing is making sure the primer is seated just below flush and keeping your bolt / BCG clean so your firing pin area doesnt get gummed up.
CCI mil-spec primers use a slightly harder metal for their cups, and a slightly hotter primer mix to enhance lighting military powder charges (almost a magnum mixture).
Federal brass was once considered soft (in the early 2000s), and many say their primer cups are as well. Considering Federal Gold Medal Match primers are used in match 69s, 77s, 168s, and 175s (including SOCOM 7.62mm Mark 316 Special Ball) I don't see any problems using it in auto loaders.
Not seating primers to proper depth creates a boat-load of problems.
The ONLY slam-fire I've ever experienced was with a Winchester Small Rifle primer in a National Match M16 (after Olin stopped nickel-plating them). I had sized a 5.56mm case fired in a fat GI chamber with a Dillon full-length die instead of an RCBS Small Base die. When single-loading through the ejection port at Quantico Range 4 (practicing the standing slow-fire stage of the National Match course) the fat case slammed into the tight match chamber and the inertia of the firing pin set the primer off when the bolt carrier group stopped in the locked position.
I no longer full-length size rifle cases but rather use small-base dies since I shoot my handloads interchangeably in both bolt actions and self-loaders, and I have rifles and carbines with both match and GI MILSPEC chambers.
Small-base sized cases are closer to factory virgin specs, so I have complete faith in a box of cartridges whether they're going through a blaster or a precision weapon.
Federal brass was once considered soft (in the early 2000s), and many say their primer cups are as well. Considering Federal Gold Medal Match primers are used in match 69s, 77s, 168s, and 175s (including SOCOM 7.62mm Mark 316 Special Ball) I don't see any problems using it in auto loaders.
Not seating primers to proper depth creates a boat-load of problems.
The ONLY slam-fire I've ever experienced was with a Winchester Small Rifle primer in a National Match M16 (after Olin stopped nickel-plating them). I had sized a 5.56mm case fired in a fat GI chamber with a Dillon full-length die instead of an RCBS Small Base die. When single-loading through the ejection port at Quantico Range 4 (practicing the standing slow-fire stage of the National Match course) the fat case slammed into the tight match chamber and the inertia of the firing pin set the primer off when the bolt carrier group stopped in the locked position.
I no longer full-length size rifle cases but rather use small-base dies since I shoot my handloads interchangeably in both bolt actions and self-loaders, and I have rifles and carbines with both match and GI MILSPEC chambers.
Small-base sized cases are closer to factory virgin specs, so I have complete faith in a box of cartridges whether they're going through a blaster or a precision weapon.
At the range a couple days ago the other instructors got into a conversation about this thread. We had some american eagle 55gr fmj rounds and a LWRC rifle with a standard firing pin. Also had my armalite AR-10T (which has a spring on the FP) and some federal GMM 168gr. We loaded two rounds into each mag and from the bolt locked back, dropped the bolt on each round, edje ted them into my hand, loaded them again, and repeated.
We got bored after 30 cycles of each and fired all four rounds. The 223 had a noticeable dent in the primer but the 308 barely had a mark. All four rounds fired fine...
30 Cycles of a bolt slamming home on each round with no slam fire and no FTF when the trigger was pulled. I am not very concerned about it.
We got bored after 30 cycles of each and fired all four rounds. The 223 had a noticeable dent in the primer but the 308 barely had a mark. All four rounds fired fine...
30 Cycles of a bolt slamming home on each round with no slam fire and no FTF when the trigger was pulled. I am not very concerned about it.
Having owned the M1, the M1A, and several AR's, I did a lot of homework on slamfires.
Raised primers? Maybe, but my experience is that a raised primer usually won't fire until it's hit the second time. Primers aren't supposed to become sensitized (armed) until they are fully seated, and the first strike usually dissipates its energy completing the seating process.
I have always based my expectations about slamfires on instructions by my DI about what causes them and how to avoid them. Any cartridge feeding technique that does not depend on the action functioning as designed (i.e, the round is always stripped out of the magazine) fails to take advantage of the bolt velocity retardation the stripping process generates. Consequently its unrestrained velocity is high enough to propel the floating firing pin sufficiently to ignite the primer.
IMHO, slamfires are more likely to be a consequence of improper single feeding technique; precisely as my DI instructed me.
Greg
Raised primers? Maybe, but my experience is that a raised primer usually won't fire until it's hit the second time. Primers aren't supposed to become sensitized (armed) until they are fully seated, and the first strike usually dissipates its energy completing the seating process.
I have always based my expectations about slamfires on instructions by my DI about what causes them and how to avoid them. Any cartridge feeding technique that does not depend on the action functioning as designed (i.e, the round is always stripped out of the magazine) fails to take advantage of the bolt velocity retardation the stripping process generates. Consequently its unrestrained velocity is high enough to propel the floating firing pin sufficiently to ignite the primer.
IMHO, slamfires are more likely to be a consequence of improper single feeding technique; precisely as my DI instructed me.
Greg
I have always loaded CCI 450 for my .223 loads.
As I understood (and the article linked to reinforces) the CCI 450 and CCI #41 (mil spec primer) differ only in the anvil to cup distance. Both have the thicker cup metal and basically a magnum primer. The #41 has a couple of thousandths more space between the cup and anvil.
I have heard that the Remington 7 1/2 is the primer they load in mil spec ammo. The article does state that this is the primer recommended by Remington for use in .223 rounds.
I cannot see how the anvil came "come loose" from repeated rechambering. There is not really any place for it to move.
As I understood (and the article linked to reinforces) the CCI 450 and CCI #41 (mil spec primer) differ only in the anvil to cup distance. Both have the thicker cup metal and basically a magnum primer. The #41 has a couple of thousandths more space between the cup and anvil.
I have heard that the Remington 7 1/2 is the primer they load in mil spec ammo. The article does state that this is the primer recommended by Remington for use in .223 rounds.
I cannot see how the anvil came "come loose" from repeated rechambering. There is not really any place for it to move.
The only time I've ever personally seen a slamfire was in an AR10 platform with factory Hornady 6.5 Creedmoor ammo. I believe that specific primer cup must have been manufactured with a defect because not only did it slam fire but it also pierced the primer.
I think it's ironic that this whole thread was started because someone else started throwing out bullshit about the dangerous slam fires with primers that weren't "mil-spec" allegedly destroying semi-autos and cited stories where they were top loading semi-autos which you're not supposed to do, and the one that was destroyed was a result of the cartridge being improperly made and not fully chambered. Somehow that relates to non-mil spec primer + semi-auto = slamfire + destroyed firearm...
"I didn't know you weren't supposed to ever re-chamber a round. When we're hunting I put one in the chamber, and when we get back to the camp house I remove the unfired round from the chamber and put it back in the magazine. It will be the round on the top of the mag, so that one may get re-chambered at least a few times before it ever gets fired. Is this a big no-no for hand loaded ammo only? Damn....I feel like a dumb-ass asking these questions."
To answer your question: Once you chamber a round in a semi-auto with a free floating firing pin, there is a chance the firing pin has tapped the primer with enough force to compromise the primer even though you can not see any deformation with the naked eye. Therefore it is a good idea not to re-chamber that round as it poses a potential for a misfire. though this is not a hard and fast rule, it is erring on the side of caution and if you are in competition, it might be the death blow to your chances. best to fire it when it doesn't really matter.
To answer your question: Once you chamber a round in a semi-auto with a free floating firing pin, there is a chance the firing pin has tapped the primer with enough force to compromise the primer even though you can not see any deformation with the naked eye. Therefore it is a good idea not to re-chamber that round as it poses a potential for a misfire. though this is not a hard and fast rule, it is erring on the side of caution and if you are in competition, it might be the death blow to your chances. best to fire it when it doesn't really matter.
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Hell yes I'm picking a fight with him. You asked me to have any continued responses over here. Now you don't want me to respond here? Make up your mind. And maybe you should go back and read because like him your accusation of a personal attack first is unjustified since I actually didn't call him any names other than "sunshine" up to that point. And top loading a semi-auto when you know you're not supposed to and then blaming the primer for it is being an idiot. Your rules for discussion along with several others here is the reason you get such responses. You guys want to have it your way and be allowed to make personal comments back but then pass judgement on the responder for the same thing. Let me know when you're off your soap box...
I've only shot cci's...400's and br2's through my Springfield m1a supermatch in highpower tournaments/practice and Sr25's and Obr and never had an issue with slam fires (and I'm talking about rapid fire stages too). I use to use federal primers in all my guns but switched to cci cause the cups are known to be alittle harder and have a consistent ignition. In all my gas gun's I use geiselle triggers to set them off. I'm waiting for a geisselle m1/m1a trigger, hint....hint....hahaha naa j/k! My local National Guard armorers worked my M1A and M1 triggers to the point they are some of the best triggers my finger has come across (even the CMP armorers at Camp Perry were impressed that my trigger was so crisp and safe that I could pass the weight requirement....AFTER they saw my trigger broke a 1lbs less of legal and altered it accordingly). I wasn't trying to cheat, I swear I didn't think it broke more than 4.5 lbs!
The only slamfires I've ever seen (or heard of) in an AR were people using low mass carriers and full mass firing pins. There's a pretty good chance that combo will do it. Even then, the rifles just doubled and were completely undamaged. The fix is to put a Ti firing pin in instead.
