Author Topic: Problem scope base holes (alignment) How to Fix  (Read 4181 times)

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Offline trotterlg

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Problem scope base holes (alignment) How to Fix
« on: December 28, 2009, 02:31:38 PM »
Here is the patient with the problem, this is a 45 Colt Carbine barrel, the scope base holes are drilled with the base at an angle.  



This is the setup I use to check how level the scope base is and to drill new holes in the shotgun stubs I use.  Kitchen counter top with a back splash.



The barrel as sent from the factory has a canted scope rail, I use a piece of cleaning rod to lay across the scope rail and sight against the back splash of the counter.



Properly aligned and level looks like this.



With the scope base screws removed, slide the scope base forward a little more than one screw diameter to get some new metal to drill new holes in.  Attempting to plug the old holes and drill part way into the old hole will probably fail and result in a mess.  With the scope base level and aligned, and without touching the base or barrel, put one drop of super glue into the front and rear hole, wait 10 minutes.



Now out to the drill press and mark the holes, I use a drill that will just clear the hole in the base with no slop, this puts a mark exactly in the center of the scope base hole, it is about a .140 inch drill bit.



Now just give the rail a sharp tap with something and shear if off the barrel.  Using a tap size drill for the scope base screw (.120) I think, drill the holes with the press. Remember to set the depth stop so as not to drill into the chamber which would be an undesireable event.

Now the taps.  From top to bottom a standard tap, a plug tap and a bottom tap.  The standard taps are kind of worthless in shallow holes, so start the threads with the plug tap and then move to the bottom tap.  



One thing I forgot to mention, before you drill the new holes, and for sure before you tap the new holes, put filler screws into the old holes.  This supports the thin wall between the old and new holes and keeps you from breaking through it with the drill or tap. (Don't ask how I learned this)



Now just clean it up and mount the scope rail in the new holes.  Good luck, yours results may vary.

Larry
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Offline handi243

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Re: Problem scope base holes (alignment) How to Fix
« Reply #1 on: December 28, 2009, 03:07:55 PM »
great work do you find alot of barrels with this problem?

Offline Slufoot

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Re: Problem scope base holes (alignment) How to Fix
« Reply #2 on: December 28, 2009, 03:12:40 PM »
Hey Larry, Thank you for this great post!
Excellent information with great pictures.
Very nice work!

GOOD SHOOTING!
Slufoot

Offline cwlongshot

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Re: Problem scope base holes (alignment) How to Fix
« Reply #3 on: December 28, 2009, 03:16:44 PM »
As always Larry, WELL DONE!!!

Another GREAT, well written and informative post for the FAQ's!!!

CW
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Offline trotterlg

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Re: Problem scope base holes (alignment) How to Fix
« Reply #4 on: December 28, 2009, 03:20:25 PM »
This is the first one from H&R I have seen like this, I do have a Rossi that was way off.  Larry
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Offline zoner

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Re: Problem scope base holes (alignment) How to Fix
« Reply #5 on: December 28, 2009, 03:44:23 PM »
thanks larry....mike

Offline quickdtoo

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Re: Problem scope base holes (alignment) How to Fix
« Reply #6 on: December 28, 2009, 04:48:20 PM »
Nice work Larry! Looks like they did the same thing to the base mount holes as they've done to some of the front sight dovetails on the carbine barrels.  :-\

Tim
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Offline zoner

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Re: Problem scope base holes (alignment) How to Fix
« Reply #7 on: December 29, 2009, 03:11:48 AM »
well, I'm a happy camper....not only did i get my barrel fixed this post is the equivalent of this wizard lettin us all look over his shoulder while he does the work...a very good learning experience...what could be better?

Offline blind ear

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Re: Problem scope base holes (alignment) How to Fix
« Reply #8 on: December 29, 2009, 08:53:15 AM »
Zoner, +1, eddiegjr
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Offline petemi

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Re: Problem scope base holes (alignment) How to Fix
« Reply #9 on: December 29, 2009, 09:23:59 AM »
Larry, that is excellent information.:D :D  I'm sure Tim'll stash it in the FAQs.  What's this with all the carbine barrels misdrilled ??? ???  Man, I'm grateful mines O.K......perhaps it's not, and I'm just too cockeyed to see it. ::)  It's on paper and shooting fine.  I just need a quiet, still day to zero it.  Thanks for the effort Larry, you're appreciated.  Happy New Year.

Pete



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Offline quickdtoo

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Re: Problem scope base holes (alignment) How to Fix
« Reply #10 on: December 29, 2009, 10:10:56 AM »
I put it in the FAQs immediately after I replied, but thanks for the reminder Pete, I too often need remindin!!  :D

Tim
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Offline dpe.ahoy

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Re: Problem scope base holes (alignment) How to Fix
« Reply #11 on: December 29, 2009, 03:58:32 PM »
Thanks Larry.  As always, when I read something from you, I learn.  Excellent pics and and language I can understand!  DP
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Offline canon6

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Re: Problem scope base holes (alignment) How to Fix
« Reply #12 on: December 29, 2009, 04:12:39 PM »
Plus  , kudos as always ,      Doug
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Offline yukondog

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Re: Problem scope base holes (alignment) How to Fix
« Reply #13 on: December 29, 2009, 04:15:25 PM »
Thanke Larry,good and easy read with pitchers to boot.
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