So primers being short as they are, and me being relatively new to rifle reloading, I saw a brick of Remington 6 1/2 small rifle primers. Asked the shop owner if they were good for AR, and he said "Sure".

So now doing some reading, I find they're really not. They're made for lower pressure rounds and the .223 doesn't fall into that category. Some guys have said as long as you load on the low end (and I do. Just punching paper), they're OK. Others say pierced primers can result and damage to bolt. So I'm not gonna load them. I also read they can be substituted for small pistol primers and used to load 9MM or .38 Special, and I load both. Truth to this?

I also grabbed 3 bricks of CCI Small Rifle Primers, but the Magnum box. Number 450's instead of 400. Box looks so much alike. I have read they work fine in loading .223 for AR's. Truth to this?

Times like these, beggars cant be choosers, so I want to use them.

Advice would be appreciated.

I've probably used 6 1/2s but not in ARs. Don't load hot and you'll be okay. Your CCI450s are perfect for ARs and recommended. I've used a lot of 400s without problems in ARs, but many claim they're not the best choice like the Remington 6 1/2s. Do some searching, there's probably a lot of information online regarding this.

I've used 6 1/2 primers in .223 Rem and in the AR platform without issue.

It's not something that's recommended, but in a pinch it...

As posted above, the 450's are the ones you want.

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USA Shooting Supporter

But can I use the 6 1/2 in a pistol if needed? I have shot a bunch of the CCI 400’s. No problems.

Do a search; you'll be able to decide.

I've done just that. Some say use them in AR, they're fine.

Other's say don't use them in AR, the primer will be pierced and bolt damaged.

Some say they're fine in pistols, and they have loaded many thousands of rounds.

Others say they're dangerous in pistols.

All pretty evenly distributed.

The 6 1/2s will wirk fine in an AR. If a primer pierces, it will erode the firing pin - which you will need a magnifying glass to see. Just xheck for a black spot in the primer dimple. Firinf pins are $5.

There are a lot of myths about ARs and primers.

I'd use the 450s for the AR, and the Remington 6-1/2 for pistols. In fact I have used the Remington 6-1/2 primers in pistol cartridges. As long as your pistol doesn't have a "tuned" action with a light mainspring the Remington 6-1/2 primers will work just fine. Dangerous? HARDLY.

For all practical intents and purposes the only difference between standard SRP an SPP is the SRPs have a slightly thicker cup material. That's why some pistols with a lightened mainspring may not ignite them with 100% reliability. But any stock pistol should fire them off with no problem.

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Here's the deal: the 6 1/2s and 400s have thinner cups than 7 1/2s and 450s. In theory, and allegedly in practice, they do not withstand higher pressures as well as the 7 1/2s and 450s. I've not experienced this problem using 400s in an AR, but I never load heavier than a recommended maximum .223 load. A max 5.56 load is a little warmer. The "stouter" primers are less likely to slam fire than the thinner-cupped primers. Maybe so.

That's only a very basic summary. An adequate search here might turn up more information, but I think you'd find better and perhaps more information elsewhere. Any doubts, just don't use the 400s or 6 1/2s in ARs with heavy loads.

As with every other subject imaginable, some say one thing, others say something else, and then a surprising number of others simply repeat something they read somewhere and have no experience at all. Some things never change.

Remington "does not recommend" the 6 1/2 for .223. No specifics given, and perhaps some overblown liability concerns are involved, but I generally go by a manufacturer's recommendations whenever possible. They don't make them for no reason.

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Pisgah

Thanks for the replies. I started with 400’s figuring they were the way to go. Loaded probably 2000 and have shot several hundred with no issues. The 450’s I bought by accident thinking they were 400’s. Glad they work so well and will load them when I get through the 400’s.

The 6 1/2 will sit for now. At my reloading pace it will be a couple of years until I get through the 400 and 450’s. I’d sell the 6 1/2 if it was economically worth it. Shipping Haz Mat is expensive and I’m not dealing with the legalities of it. I’d sell them if I knew someone locally.

If you can show us how a slam fire can happen with an AR15 it would be very helpful.

Never seen it happen but my understanding is that since the AR15 has a floating firing pin, and the only thing keeping it retracted is the spring, it is possible for the firing pin to slam forward into the primer when the bolt closes.

Or at least that is the explanation CCI gives for why they make and recommend using # 41 small rifle primers when reloading ammo for use in AR pattern rifles.

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There's no spring.

I've never actually disassembled a BCG, but looking at the parts diagram it appears you are correct. Learn something new every day.

Without even spring tension to hold the firing pin back and retracted, having it slam forward into the primer with enough momentum to fire a round when the bolt slams closed seems even more likely, don't you think?

I always assumed there was at least a light spring holding it in the retracted position. Seems to me like that would add at least a small measure of safety over having a completely free-floating firing pin.

Now I really appreciate CCI's warning.

Since the magnum rifle primers have slightly thicker metal in the cups, just like the #41 SRPs, they also would provide the same slam-fire prevention.

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Extract a live round after it's been chambered semi-automatically. Most, maybe all primers will show a very slight indentation from the firing pin. While I've had good results using non-magnum primers like the CCI-400, there's a bit of extra safety margin in using the CCI-450 that has a slightly thicker cup. If you're not using stout loads, maybe it doesn't matter, but it hurts nothing to develop loads all AR loads, even less than maximum, using a CCI-450, a Remington 7 1/2, or something similar.

The firing pin cannot touch the primer until the bolt has rotated into the engagement lugs of the barrel extension.

Well then I recon you better tell CCI, and rockquarry, and everyone else who has seen exactly what he referenced (dimpled primers from the bolt closing on a new round).

'Cause you obviously know somethin the rest of the AR shootin world doesn't.

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I agree with the slam fire possibility with a thin base primer and it is absolute true that you can see a light firing pin mark on an unfired case taken from the chamber of an AR after it has cycled. Additionally, the 6 1/2 Remington primers were designed for low pressure rounds such as a 22 Hornet, 25-20, etc. If you puncture a primer, you will likely etch the bolt face and possibly the firing pin and a magnifying glass is not necessary to see it...

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S&W factory revolver armorer

Just because you don't know what you're talking about doesn't mean I'm as clueless.
There's a difference between a dimple and a slam fire. If you understood how the bolt rotates on an AR15, you would know that it is very unlikely for a slam fire to happen. Zillions of non-magnum primers are used in reloads for AR's with nary a problem. The only real problem is pierced primers with hot loads as that will erode the firing pin.

Like I said earlier, there are a lot of myths about primers in ARs.

This forum has taught me a lot about reloading. It was invaluable when I started back in 2013. My reloading practices are so basic. Find what works and stick with it. I’ve loaded probably 1500 cases with non magnum primers, half CCI and half Federal. The ones I have shot so far have fired no problem. I mistakenly bought the CCI 450 magnum primers but now I find they’re recommended for AR so I’ll try to stick to those from now on. In these days of primer drought craziness we can’t be picky but I have ruled out using the 6 1/2 Remington. Just goes against my whole “stick with what’s safe” philosophy. Slam fires, pierced primers, damaged bolt and firing pin, maybe ok for pistol maybe not. Who needs the hassle? They’ll sit in the cabinet until I can find a way to trade or sell them. They’d already be on GB if it wasn’t such a hassle and expense shipping them.

Well you sure put me in my place

That is why I specifically referenced info from the primer manufacturers. I figure they know more than I do. Unlike you I don't know it all, and I have no problem admitting it.

Forgive me for taking your inquiry about slam-fires as a serious question. I see now it was just a troll for an opportunity to start an argument so you could show us all how much smarter than everyone else you really are. Including the folks like CCI who manufacture primers and ammo. My bad, not a mistake I'll make again.

If a factory loaded round with the proper thick-cupped primer exhibits a "dimple", it stands to reason that a primer with a thinner cup will show an even deeper dimple. Deep enough to fire? Maybe, maybe not. Most people don't want to find out the hard way. That whole "safety" thing.

The fact that you say it is "very unlikely" rather than "impossible" is a tacit admission that it can happen. It is very unlikely that I will ever have to defend myself with a firearm, but I carry one every day anyway. I have fire extinguishers and a spare tire too - even though it is "very unlikely" that I will need them.

If the primer manufacturers caution against using regular primers for AR rounds, I am just ignorant enough to believe them and follow that recommendation. Just like following the other recommendations in all the other published reloading data I use.

I guess I'm kinda stoopid that way

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Hi BC38,
Back in the early to mid 90's during some politically induced primer/ ammo shortage I worked for a company that had a chemical contract with Winchester Western.
I was loading a lot and I got to the point where I was going to have to quit competition due to the lack of small pistol primers.
I cornered their sales rep, made my case to him and was rewarded with the ability to purchase 10,000 small rifle primers as "The best I can do" says he.
We were loading 38 supers to the old 200 major power factor and I burned them all up in hot supers and mild 38 special Bianchi cup loads.
I can't say they are safe in every application, but from hot supers to midrange 38 special loads covers a lot of range.
I do remember there was very little difference on the chrono in FPS pistol between pistol primer and rifle primer loads.
The revolver main spring had to be sprung a little heavier due to harder primer cups.
As someone who has done it before, I would do it again if I had to and not feel bad about it
Good luck to you