Is 5.56mm military safe in newer production Ruger Mini-14s?

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Redington Slim

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Nov 3, 2007
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Is 5.56mm military ammo safe to shoot in Ruger Mini-14s? According to SAAMI the use of military ammo causes higher than safe pressures in civilian guns because of different chamber dimensions in military vs civilian guns. Military guns have a longer freebore. Does anyone know if the newer versions of mini 14's have a longer freebore to make them compatible with 5.56mm?
 

Redington Slim

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Nov 3, 2007
Messages
405
Slippingaway, Yes, I am aware that Mini 14s of all years will fire 5.56. You missed what I am asking.

I found this excellent concise explaination on Wikipedia (http://en.wikipedia.org/wiki/.223_Remington) and wanted to share it on this forum.

"The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a .224" diameter, jacketed bullet, with weights ranging from 40 up to 90 grains, though the most common loadings by far are 55 grains.

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive leade. [3] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[4] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56 mm ammunition".

So again, with added information to clarify my question: Does anyone know if Ruger has modified thier chambers in later/newer production rifles to safely shoot military 5.56 ammo?
 

Sig685

Single-Sixer
Joined
Oct 21, 2003
Messages
177
The current (and past) Mini-14 manual states:

"The RUGER® MINI-14® RANCH RIFLES are offered in two calibers: the .223 Remington (5.56mm) cartridge and the 6.8mm Remington SPC cartridge.
The Target Model uses .223 Remington cartridges only."

Since it specifically states that the Target model is only chambered for .223, I would really follow that recommendation for users of Target Model.

Your Wikipedia article (like most other Wikipedia articles, is wrong. The 5.56 military cases are not thicker than commercial ones, they are actually thinner. I handload a great deal of .223/5.56 cases and I use a smaller bushing for LC cases, because the brass is thinner. I have a bushing that is .004 bigger for Winchester and another .004 bushing for Lapua brass.

For fun and excitement, take what is a max load developed in an LC case and put it in a Winchester case and see what happens. Been there, done that; got the pierced primers. Thank God it did not put that in a Lapua case.

If the Ruger manual, after pages of lawyerese from various states, c;early says on page 12, that you can fire .223 and 5.56 in the Mini-14, with the noted exception of the Target model, I think they are saying that you can safely do that.
 

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