Ed Harris Friday: My Observations on the Ruger Mini-14
Friday, February 24, 2012 Filed in: Rifles
My Observations on the Ruger Mini-14
by Ed Harris
(Editor’s Note: Today Ed candidly talks about the Ruger Mini-14, a gun with which my wife and I have a love-hate affair. She likes the size, the handling, and the appearance, while I like that it uses a round which I already have in abundance! When we went looking for a rifle for her, we acquired and quickly disposed of several examples as we couldn’t find one that was both accurate and reliable. Now that Ed has identified the cure for its accuracy woes, and Ruger is finally making reliable high-capacity magazines, perhaps it’s time for us to revisit the Mini!)
When I was at Ruger I tested hundreds of Mini 14 rifles of all configurations, conducting audit shoots of normal production, as well as R&D testing of the full-auto AC556, AC556 and the experimental XGI rifle in .308 Win, and assisting in the development of the Mini Thirty in 7.62x39.
To be COMPLETELY honest I was disappointed with its accuracy when compared to the M16A1 and A2 rifles, with which I am very familiar. The Mini 14 gives reasonable performance for an American-made rifle in its price range, and is safe, serviceable and reliable. It just isn't all that accurate. You can find individual rifles which shoot well, but these are statistical aberrations.
We tried to test a large enough sample of rifles to pick "good" ones, then painstakingly took them apart and gaged every part to see if we could tweak tolerances or make design changes which would significantly improve accuracy without increasing production cost. It couldn't be done. We did learn a few things, however.
The long run average group size for standard Mini-14 rifles fired from a test stand is about 4-5" for ten-shot groups with M193 or M855 ammunition of "average" quality, producing an acceptance Mean Radius of 1.6-1.6" at 200 yds from a test barrel. The M16A1 or A2 do this at 200 yards from a machine rest. I believe the biggest factor in Mini-14 accuracy is irregular contact between the gas block and the face of the slideblock, welded to the slide handle (aka operating rod).
If you disassemble the rifle and inspect the face of the slide block and the rear of the gas block assembly, you may find that the face of the slide block strikes one side or the other of the gas block, rather than making a uniform and symmetrical imprint. This asymmetrical contact causes fliers. The fit-up can sometimes be improved by grinding 0.005-.010" off the face of the slide, so that with the slide fully forward, a .001" shim can be inserted between the slide block and gas block and be clear all the way around. This way the forward motion of the slide is stopped by the right locking lug in the cam pocket of the slide handle, rather than by the slide block slamming against the gas block, as is the case with the M1 Garand rifle.
I caution against removing the gas block, because these are installed in a fixture at the factory to insure proper alignment. There is a small bushing in the gas block which locates it on the barrel. You must be careful not to lose this. This is why the gas block screws are staked in place on newer guns.
The condition of the muzzle crown is important as well as the straightness of the barrel. Sometimes the barrels are bent when pressing the front sight on. Usually they catch this at the factory and they correct them if it causes fliers in the range, but since they only shoot indoors at 50 yards, for a 2" group, the accuracy standards are more in keeping for a plinking rifle than for the serious accuracy enthusiast.
The Mini-14 chamber conforms to U.S. dwg. #8448649, which is used for the M16A1 chamber. It has a .225" cylindrical ball seat with a slight freebore. I do not believe the GI chamber causes any inaccuracy in this type of rifle, because I have fired thousands of rounds in heavy test barrels with this chamber which gave fine accuracy.
For an accuracy load I suggest 21-22 grs. of 4198 (either IMR or Hodgdon) with the 52 or 53-gr. Sierra bullets loaded to 2.25" OAL, or 23-23.5 grs. of H322. The 52-gr. Nosler solid base also is quite accurate.
The Mini-14 Ranch Rifle was also made in .222 Remington for the export market to France, Belgium and Italy where civilians are not allowed to own firearms of military caliber. Overruns were sold in the U.S.