That’s not quite correct, but there’s a grain of truth there.
Back before the earth cooled in the pre SGW days when:
- Colt was the only company that made the AR-15; *and*
- after Ruger modified the 180 series Mini 14 to the 181 series,
that was true, but the difference was small - small enough for most shooters to ignore.
Prior to the 181 series, which was extensively modified to reflect commonality with the select fire AC-556 that was developed from (and after) the 180 series Mini 14, the 180 series Mini 14 was a solid 2 MOA rifle right out of the box. Jeff Cooper even gave it positive reviews.
I’ve posted on this forum before about the changes from the 180 to 181 series with pictures showing the changes and much greater reciprocating mass of the later series. Those changes no doubt helped durability and reliability in the select fire AC-556, but they didn’t help accuracy in 181 and later Mini 14s. The post 180 series Mini 14s were commonly 3 to 5 MOA guns, with the faster 1-7 twist barrel examples being some of the worst with lower grade 55gr FMJ for reasons I won’t get into unless someone asks.
The average Colt manufactured 20” M16 style 1-12 twist AR-15 was capable of about 1.5 MOA 5 shot groups out of the box with decent factory 55 gr ammo. In comparison the average 1-10” twist 180 series Mini 14 was capable of about 2 MOA accuracy with the same ammo.
At that point the Colt AR-15 was arguably slightly more accurate than a Mini 14 (or the AR-180, which was also about 2 MOA). However both the Mini 14 and the AR-180 were about 25% less expensive than an AR-15. The choice then was a little more accuracy with an AR-15 that cost more, or a little less accuracy with a Mini-14 for less money - and looks and handling similar to the then very popular M1 carbine.
With the subsequent 181 series Mini 14 however accuracy went south and went farther south as the tooling aged. That’s the point where your statement where any AR-15 was more accurate than any Mini 14 was true. That was also the point where Ruger started losing a lot of market share to the AR-15 - especially as the M16s initial very negative reputation from its initial introduction in Vietnam began to fade.
The relative accuracy stayed that way until the Mini 14 was re-tooled with the 580 series, and then given a heavier tapered barrel mid 580 series. Those mid 580 series and subsequent Mini 14s are again solid 2 MOA rifles out of the box - on par with most non match AR-15s.
However, before that retooling happened, Colt’s patents expired and other companies started reverse engineering the AR-15, with SGW / Olympic Arms leading the charge. SGW made good stuff. However over the last few decades since there have been some very poor quality AR-15 clones produced, particularly in M4gery form. I’ve seen some of those that are only 5 MOA accurate on their best day.
From that later perspective, your statement about relative accuracy between AR-15s and Mini 14s also isn’t true.
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Below is a 187 series Mini 14 Ranch Rifle with a 1-10” twist barrel and a Colt manufactured M16A1 upper on an NDS-601 lower. Both of these, along with my similar configured 20” Colt SP1 and my 184 series Mini 14, shoot 5 shot 1.5” groups at 100 yards with both Black Hills Ammunition and Hornady 55 gr FMJ ammo.
To get the older 18x series Mini 14s to shoot like that you do need to do some work to them:
- a Choate flash hider (which adds muzzle weight and improves harmonics);
- a SOCOM style Accu Strut (which stiffens the barrel and helps harmonics); and
- a smaller gas port bushing (usually around .045” as opposed to the stock .080”, which cures the over gassed issue and reduces the problems of excessive slide velocity on vibration and accuracy.
A shock buffer also helps and the Tech Sights rear sight is a much better rear sight.
