Picatinny rail modification.

Over the weekend we were down Tekapo shooting long range gongs. It was discovered at just over 1250m my brothers scope ran out of elevation. On investigating the turret there was with a 100m zero 35moa below the zero. No wonder the top end was limited. He is running a 20moa picatinny so needs a 40moa which are not common for a Tikka T3 Varmint. So he will probably get the rail machined. The question is with the rail at 139.50mm long how much should be removed from the front to get another 20moa?
Thanks to those with different brain to me.
Jeremy

200 thou?

just fold up coke cans till you have enough shims bro... then test and adjust...Chur!

whatever the difference between back and front is currently, again?

Or get the Burris rings with offset inserts.

You guys are a hoot, so #1 not really scientific enough but might work #2 current difference in thickness is about 0.030 so again would work if there was nothing else in play say the receiver not totally inline with the bore. #3 trying not to spend more hard earned money on hardware. But hey keep the suggestions coming someone might chance on the correct answer I just wont know it when I see it.

If you skim the bottom of the rail at an angle the screw holes will no longer be at right angles to the base of the rail.

You know at 100 yards 20moa is 20inches so just calculate it back to 139.50mm

In here maybe, my brain is sleepy
How to calculate machining angle 20 MOA taper [Archive] - Benchrest Central Forums

Pie - thag - o - rus

Difference in thickness front to back of existing 20 rail times 2. And need to remove front and back, or otherwise you'll torque the rail.

Should work...... maybe...... sort of..... of course it will...... hold my beer and watch this

Quote:

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Originally Posted by DPT

If you skim the bottom of the rail at an angle the screw holes will no longer be at right angles to the base of the rail.

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That will be insignificant when you consider the angles and tolerances of the threads and holes.

Quote:

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Originally Posted by DPT

You know at 100 yards 20moa is 20inches so just calculate it back to 139.50mm

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139.5 * 20.94/(36*100) = 0.811mm

send the rail to Waitaki Engineering and get it done properly . . they did a 45MOA rail for me, fast and resonable price

i would also get Burris XTR rings with offsets, youll get another 40MOA

R.

Coke-can-a-rus just shim it till it is where it needs to be...

Thanks for the info guys. The rail is at the machine shop getting a 0.035 skim so that should fix it. That it will then make it about 40moa total

Jeremy

Its only 0.33° so I would worry about holes not been at perfect 90° to the rail, there'll be enough tolerance it the holes to compensate.

http://i964.photobucket.com/albums/a...ps00fugf18.jpg

It's just a shade under 1mm that needs to come off the front end of the rail, obviously nothing to come off the rear.

Kj

Just a thought, but if you know that you have about 35moa from bottoming out, why not make the rail just short of that, then you'll end up with a poor man's zero stop.

I did this to my rifle, its about 1moa from absolute bottom for a 100y zero.