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I know it has been discussed here before but after searching I can't find the thread.

Does anyone have a Ruger Factory document/reference on 5.56 use in the Mini-14?
Early models https://ruger-docs.s3.amazonaws.com/_manuals/mini14-181-186.pdf
and later models https://ruger-docs.s3.amazonaws.com/_manuals/mini14-181-186.pdf
both say:
The RUGER® MINI-14® RIFLES are chambered for the .223 Remington (5.56mm) cartridge. The Mini-14 Rifle is designed to use either standardized U.S. military, or factory loaded sporting .223 (5.56mm) cartridges manufactured in accordance with U.S. industry practice. See “Ammunition Notice” & “Ammunition Warning”, below.
 

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If all else fails...read the manual or perhaps the earlier replys.

11 year old post that was settled years ago.

Reloading dies are the same.
 

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FYI:
62grain SS109 5.56 NATO will damage your mini. I learned the hard way after going through about 1200 rounds of the stuff. The tab on the op rod/slide assembly got dented, and began slipping out of the channel on the receiver. :(

I picked up the new slide assembly recently, now I'm considering the adjustable gas block, to prevent this from happening again. I will probably do it the next time $100 bucks falls in my lap.:eek:
If that damaged your rifle, then ship it back to RUGER for them to fix it.
 

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They need to make sticky that flashes like neon sign on thus subject. My word it's been hashed over ad nauseum.
 
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They need to make sticky that flashes like neon sign on thus subject. My word it's been hashed over ad nauseum.
Stop the madness. :p
 

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Let's start at the beginning of this confusing issue: First, there are 3 different cartridges in question, a civilian 223 Rem, a US Military 5.56x45 (M-193, 55gr), and a 5.56 NATO (often called a 5.56x45 NATO). The 223 Rem is a civilian version of the military 55gr M-193, 5.56x45 cartridge and are safe to shoot in any rifle chambered for a 223 Rem, 5.56x45, or 5.56 NATO. The confusion comes with the 5.56x45 NATO cartridge which is only safe to shoot in rifles chambered for the NATO cartridge. Why? It is loaded with a 62gr bullet that has the ogive on the bullet farther forward to improve it's ballistic coefficient so rifles chambered for the NATO cartridge have a longer throat.

On 28 October 1980 the 5.56 NATO cartridge was standardized for NATO forces so if your rifle was made before 1981, there was no such thing as a 5.56 NATO cartridge. thus no rifles made before 1981 were chambered for a 5.56 NATO.

Ruger Mini-14's went into production in 1973, at least 7 years BEFORE the 5.56 NATO cartridge was available so if you have an older Mini-14, it is NOT safe to shoot 5.56 NATO ammo, however 5.56x45 USGI ammo is safe to shoot.

How can you tell the difference in ammo? Civilian factory cartridges will have a headstamp that indicates "223 REM", pretty obvious. USGI 5.56x45 cartridges will have a military headstamp with a 2 digit date and the manufacturer code. This would include WCC, FC, and LC. USGI 5.56x45 cartridges are loaded with 55 gr bullets. 5.56 NATO cartridges have a headstamp similar to USGI ammo .... a 2 digit date and the manufacturer code plus they have the NATO logo, which looks like a view through a scope .... a circle with crosshairs. 5.56 NATO cartridges are loaded with 62gr bullets, never 55 gr, however some special purpose 5.56 NATO cartridge could have bullets as heavy as 77 gr (service rifle match grade).

To avoid confusion, look for the NATO logo headstamp (circle with crosshairs). If the cartridges have the NATO logo, they are NOT safe to shoot in a rifle chambered for 223 Rem or 5.56x45 USGI. If the cartridges don't have the NATO logo, they are safe to shoot in any 223 Rem, 5.565x45, or 5.56 NATO chambered rifle. Pretty simple!
 

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IIRC 5.56 is thicker at the neck and creates significantly more chamber pressure.

I know for a fact that firing a .223 round in a 5.56 weapon has no ill effect. The converse is also true is that firing a 5.56 (repeatedly) will damage the .223 weapon (over time).

What I don’t know (for sure) is whether the Mini 14 is truly a 5.56 weapon.
Having read through some of these discussions, I believe there is a target Mini 14 that can only use .223, but all other Mini 14s can use either.
 

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Paladin, Not true. Minis made before 1981 were NOT chambered for 5.56 NATO. Read my above post. There were three cartridges in question, not just two!
 

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So how many chambers for .223 are there in the Mini 14?
And see post 108.
 

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IOWEGAN, thanks for that explanation. I've been shooting M193 in my 1977-vintage 181 since I got it in 1980, with zero problems. I always thought the M193 was a NATO designation. I have held off shooting (or even stocking) M855, even though my newer Mini-14s can handle it. It is reassuring that the little voice in my head that shunned M855 was right. I have no desire to mix M855 with my .223 and M193 stockage, but pretty much consider .223 55gr and M193 as completely interchangeable with all three of my Minis.
 

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Sr40Ken, As far as I know, there are just two chambers for Mini-14s. The target model and early production models were chambered for 223 Rem and USGI 5.56x45 through serial number 182-45600. After early 1981, Mini 14s, with the exception of Target Models, were shipped with a hybrid chamber designed to allow 223 Rem, 5.56x45, and 5.56 NATO ammo to be safely fired with good accuracy. This chamber is much like a 223 Wylde if not identical.

RFJ, M-193 is a US Govt Issue (USGI) designation with 55gr FMJ bullets. This was the original cartridge designed for the M-16 rifle before NATO got involved. The history is interesting because the cartridge started off as a 222 Rem then it was extended and called a 222 Rem Magnum. Later it was renamed the 5.56x45mm (M-193). Remington developed the cartridge so they made a civilian version called the 223 Rem. It had exactly the same specs as a M-193, just a different headstamp and no peened primer. Later loadings for the 223 Rem included JHPs and lighter weight bullets producing a range from 40 to 55 gr. All of these 223 Rem variations can be fired in any 223 Rem, 5.56X45, or 5.56 NATO chambered rifles.

The US military was trying to get NATO to approve the M-16 rifle and M-193 ammo however the cartridge did not penetrate well at longer distances so the FN factory in Herstal, Belgium experimented with several new bullet designs. They came up with the SS109, SS110, and SS111 cartridges which were later named 5.56 NATO. The SS109 is a green tip, steel core, 62gr bullet with a copper jacket. It has a much higher ballistic coefficient than the USGI M-193. It is named a M-855 in the US military and is also called a 5.56 NATO by all the NATO countries. More confusion but remember, all "M" ammo designators are for ammo made for the US military and other US Government agencies. Belgium uses "SS" types and the rest of the NATO countries just use 5.56 NATO. Many countries produce 5.56 NATO ammo and all of them use the NATO logo (circle with a crosshair). Many manufacturers world wide also make M-193 ammo by various names but they usually have 55gr FMJ bullets and do not have the NATO logo.

To add to the confusion, Federal has marked some of their M-193 ammo boxes with 5.56 NATO, however the cartridges have 55gr bullet and don't have the NATO logo on the case heads. Looks like a marketing scheme to me.
 

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RTFM.
SCARES THE BEJESUS OUT OF ME THAT SO MANY PEOPLE HAVE NOT READ THE FACTORY MANUAL TO ANSWER THIS QUESTION!
HINT: ITS IN RED LETTERS. 🙄🙄
 

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Iowegan, good explanation, thank you!
 
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yava, Herein lies the confusion. If you have an earlier (pre 1981) Mini-14, they didn't make 5.56 NATO ammo so people mistakenly think 5.56x45 is the same as 5.56 NATO, which it certainly isn't. In other words, the older manuals are wrong! Unless your manual specifically states your gun can shoot 5.56 NATO, not just 5.56x45, it's not safe. It's always better to go by the caliber stamping on the barrel but again, barrels stamped for 5.56x45 do not mean they are safe with 5.56 NATO ammo. It's easy to see how this issue is so confusing.
 
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My Mini is a 581 so I don't have to worry. That said it's fired very few factory rounds anyway. I assume my PSA and Ruger ARs are good to go. Again some of my ARs have never fired a factory round. And the most accurate round I've ran through my Mini is Hornady 55gr FMJBT to Hornady's specs, Slightly below moa in Bass Pros 100 tube.
I have a whole bunch of 62gr FMJBT to load for em. But I've never loaded 55 gr hotter than 90% of Hornady's 5.56 section.
 
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