Trouble boresighting Mini 14...

Sporting Lad

Sporting Lad

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I'm having trouble getting my Mini 14 boresighted.
I mounted a new NIKON M223 on the OEM factory rings and went to the range to get a 25yd zero. I got a tight little group 4-1/2" below my POA. Before I got my reticle to the POI I ran out of elevation
(16 x 4.5 = 72 clicks).
Now, I've successfully boresighted lots of bolt action rifles, but this is my first semi, so I went out and got a Bushnell Magnetic Boresighter to snap onto the muzzle. This Bushnell agrees with my range results, showing my POA sitting at the upper end of its grid. There's not much in the way of adjustment in the rings. On the weekend I went out and got a set of Wheeler alignment and lapping bars to check on the scope's alignment. It was spot on.
I've since tried another scope (previously sighted in on my AR) and a different set of rings (c/w the supplied Picatinny rail). All of the scope/rings combinations show the same picture thru the boresighter's grid--POA high above the bore's predicted POI.
I must be overlooking something major, or maybe very elementary, but I'm out of ideas. Could it be the machining of the receiver's mounting surfaces??
Why are my POI and POA so far apart? Is this Mini a POS??
 
I did swap the rings around this afternoon, to no avail. I even tried fitting a different pair of rings.
IDK how I can shim under one ring without changing its alignment to the other.
 
D'fuh?!

Thanks so much for those timely replies.
I came up with the same shimming idea late last night and this morning one of my shooting buddies wired me the same, so all your info re the faulty machining is, in a way, reassuring.
At the same time I'm a little miffed at Lord Ruger for making no attempt to rectify this defect, or to bother to inform Mini owners of this problem. Cheezits, I've just spent the better part of a week trying to figure this out while I might've been out enjoying our fine summer weather.
Had this rifle been a car they would have a factory recall!
(rant ends). :rolleyes:

To be continued...
 
The barrel might be slightly off. Shimming the rings will bend the scope to some extent. Burris make Scope Base Shims that are supposed to be better, I have never tried that.
Bad luck!
 
Have you tried it at 100 yet?
get a big piece of backing paper and try.
if it has a tiny little group at 25 it shouldn't be that bad at 100 and adjust from there.
Oh, and throw the magnetic bores I her in the garbage or use it hold your kids art work on the fridge.
 
I was suspicious of the boresighter, except for the fact that it's showing me the same picture as the result that I got from my day at the range:
4-1/2" low. I can just barely get the two crosses to coincide by spinning my elevation 'UP' all the way to its max, but that leaves me with nowhere
to go when I want to hit something beyond, say 200yd--it won't aim any higher. I've since reset the reticule to its 'default' position and boresighter's grid now agrees with my reality (it's predicting the same result as I got earlier).

I just backed off the screws holding the Pici rail enough to lift the back of it so that the scope's reticule coincides with the boresighter's.
According to my caliper it needs ~ 0.075"/0.20mm shim to do that.
I just happen to have some stock here that is that thickness, but shaping and drilling it will be a challenge with hacksaw and file.
Actually, this shim should be somewhat wedge shaped to account for the height difference between the front and back, but that's way beyond my
capability. Alternately the rifle's two mounting surfaces could be reground, but I'd just return it before I attempted that.

I may well try that 100yd shot before I proceed any farther with this; the range is only20 minutes away.
 
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You really need to check at a further distance. 50yds minimum. In many cases bang on at 25 will be 3 plus inches high at 100. Try to accurately measure your scope height above the center of the bore. Center of bore to center of scope. With a picatinny you're probably in the neighborhood of 2"

When I measured accurately with my rem700 I found in all the ballistic ccalculators that my minimum zero was 75 yds. Any thing closer will actually begin raising your poi at 100 and 200.

Stop for a minute and think of your scope as a sight tube like an iron sight. Its height above the bore causes you to elevate the muzzle in order to get point of aim to line up with point of impact inside 75yds.

Or just pencil sketch your rifle and scope then use a string or ruler to make a straight line from the bore to a close point representing 25 yds. Then draw a straight line through your scope to the close target. This will show you how you are raising the muzzle from parallel to the scope to get such a close zero.

I just checked Strelok using my ruger77mkii I had entered 237 yd zero for mpbr which puts me 2.65" high at 100. A 25 yd zero puts me 3.3" high at 100yds.

A 7rem mag with high rings zeroed at 25yds will be within mpbr to 500yds.

Edit. I just checked federal fusion 223 rem 62gr ammo 3000fps .310bc scope 1.97" above bore with a 100m/109yd zero is 4.06 in low at 25yds. I dont think theres anything wrong with your rifle
 
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Yes, I'm planning to hit the range tomorrow where I'll (carefully) blast away at 25, then 100yd.
But being nearly 5" high at 25, I don't expect to even be on paper at 100.
I'll report back.

SL
BTW--thx for the encouragement.
 
Your scope depending on model might not be the best choice, I have a monarch 3 on mine in low rings, 120MOA of adjustment and works fine.
Some m223 scopes are only showing 60moa of adjustment.
 
Sporting Lad said:
Yes, I'm planning to hit the range tomorrow where I'll (carefully) blast away at 25, then 100yd.
But being nearly 5" high at 25, I don't expect to even be on paper at 100.
I'll report back.

SL
Click to expand...

Back at the range yesterday afternoon. Nothing's changed since the previous session: Still hitting way low at 25yd and, as predicted, I'm not even on (BIG) paper at 100yd.
I'm returning this rifle to the store.
 
I took that Mini in to the store where I got it. They had their gunsmiter check it over, then they exchanged it for a new-in-box one. Their smiter admitted that it's a common problem with these rifles.

Today I was back out at the range with the new Mini: At 25, 50, and 100 yd
it got 3 MOA, which is about what I'd expect from a "ranch rifle".
Especially the way I shoot it.
Full marks to the merchant for standing by what they sell; not so for Ruger, tho.
Happy ending, I suppose, but I'm not too thrilled with Ruger allowing rifles like that first one out onto the streets. They'd better be careful or the Chinese
industry's quality control will overtake their hard-won "Made in USA!" reputation....
 
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