Introduction: How to Bed a Scope Base - Remington M700 .308 AAC-SD Tactical Rifle
I will be writing a series of articles that will pertain to accurizing the Remington 700, subscribe and stay up to date as the work on this rifle progesses.
The build will include:
Bedding the scope base
Installing an aftermarket Timney straight trigger
Bedding the action in a Bell & Carlson M40 stock
Lapping the bolt lugs
Barrel break in
Reviewing the Badger Ordnance mini tactical bolt knob
Installing Burris Xtreme rings and Vortex Viper PST scope
Introduction to MRAD and the scope ranging reticle
No bullcrap real world accuracy results with a variety of ammo
Range report on the AAC Brakeout Compensator
Pros & Cons of the Harris Bipod 9-13 features
This rifle will be used as a coyote thumper and also at the local tactical shoots.
I will be updating with full reports and pictures as time allows.
Step 1: The Rifle:
Remington Model 700 SPS Tactical AAC-SD
Bolt Action .308 WIN Centerfire Rifle
20" Barrel with a 1 in 10" twist
Advanced Armament Brakeout Flash Suppressing Compensator
Hogue Black Overmold Stock
I have read many opinions on whether bedding a scope base actually helps or not. The following photos will show why I think it is not only practical but mandatory for a precision rifle build.
Why bed a scope base?
Quality scope bases are machined to very tight tolerances. The top of most production firearm receivers do not enjoy this level of care and results in mounting a very straight piece of metal (scope base) onto a receiver that has run out.
This run out is very easy to determine and if not corrected can result in vertical stringing of bullet groups.
The way it works is if the front and rear of the base does not lay flat when tightened down, it will bow the scope base to conform to the profile of the receiver. This bow will then keep the scope mounts from lining up with one another and the stress is then transferred to the scope tube once the scope is mounted.
The scope base must lay perfectly flat and in an unstressed position on the receiver.
Step 2: Checking for Run Out on the Front of the Base.
Snug down the rear screw.
Try to slide strips of paper under the front of the scope base. In this example one sheet of paper makes it under the front screw hole and stops, the second sheet of paper didn't even make it that far. This is a good fit, with metal to metal contact in an unstressed position.
Note that only the far rear screw is snugged down, the screw just in front of it is installed to keep the base holes lined up, it is not snugged down.
Step 3: Checking the Rear of the Scope Base for Run Out.
Now we install the screw in the forward base hole and check for run out.
I was able to slide 4 strips of paper all the way under both rear screw holes and there was still enough room for more paper. In this case the rear of the base wasn't touching the receiver at all. If I was to install the screws without bedding the base it would bow the base to conform to the profile of the receiver.
Bowed base = stress on the scope rings = stress on the scope tube.
Would this matter in your favorite deer hunting rifle? Probably not.
Does it matter to the LEO perched 70 yards away in a hostage situation? All I can say is, the more variables a shooter can control, the more confidence he has in his shot.
Step 4: Dial Calipers Don't Lie.
For reference I measured the thickness of the 4 strips of paper.
I'm not sure how many more strips of paper would have fit under the rear of the base.
Step 5: Let There Be Light... Under the Scope Base.
Step 6: Gathering Supplies.
Kiwi shoe polish - release agent
A stolen can of Play-Dough from my daughter... I'm a terrible father.
As with most any project, the prep work takes the longest.
*Lightly sand the rear portion of the scope base.
*Thoroughly clean/degrease the base and the receiver.
*Cover the receiver and screw holes with Kiwi shoe polish. Kiwi is used as a release agent and the JB Weld will not adhere to it.
*Using the Play-Dough, fill the screw holes in the receiver and base. The tighter these holes are packed, the less chance there is for the Play-Dough to fall out. We don't want the bedding compound to seep into the screw holes and harden into a mechanical lock thus permanently attaching the base to the firearm.
Step 7: Finishing the Prep Work. at This Point Everything Is Cleaned, Kiwi Polish Is on the Receiver and Play-Dough Is in the Screw Holes.
Step 8: Applying the Bedding Compound.
Step 9: Once the Front Screw Is Snugged Down Make Sure the Bedding Evenly Covers the Base and Oozes Out on All Sides.
Step 10: Clean-up All the Overflow With WD40, Q-tips and Cotton Rags.
Now we must wait and hope that enough release agent was applied. There should be no pressure applied to the rear of the base during the hardening process.
Step 11: The Compound Fully Cures in 24 Hours But the Base Can Be Carefully Removed After About 8 Hours.
Step 12: Once Removed, Sand the Edges Smooth. a Chamfer Tool Easily Cleans Up the Screw Holes.
Step 13: Installing the Scope Base, Blue Loctite Is Your Friend.
Step 14: Proper Installation.
In this first photo I am pushing forward on the scope base as I snug down the screws. This scope base has a lip that rests against the front edge of the ejection port. The lip helps create a stable platform during recoil. By preloading the base lip against the edge of the ejection port there is little chance of the base moving seperately from the receiver once a shot is fired.
The second photo shows the lip solidly againts the ejection port. During recoil this lip accepts the energy, not the scope base screws.
Step 15: Torquing the Screws.
Snug up all four screws, then using an inch pound torque wrench, tighten to manufacturers specs. In this case the manufactures specs is 20 inch pounds.
Step 16: A Level Scope Base All Locked Down and Ready for Its Optics.
Step 17: Tactical Bolt Handle.
I'm getting ready to ship the bolt to Badger Ordnance.
They will be installing a mini tactical bolt handle that has a recessed 1/2" socket head in the handle. This is the same size as the scope ring mounting bolts we are using. The bolt knob can then be used as an emergency scope wrench if needed.
I will also do a full review on this product along with more pictures.