Date: 25 May 94  09:31:35
From: Ed Harris
To:   Chuck Weimer
Subj: Mini 14 Accuracy

My Observations on the Ruger Mini-14

By Ed Harris          Rev. 5-25-94

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 experi-
mental 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 realiable.  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 ther 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 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.


--- msged 2.05
 * Origin: Home of Ed's Red (1:109/120.3006)
 
 
 
 
 
 
 

