rifle Accurizing
January 28, 2009.
The object is to make everything concentric to the datum of the action. Blue Printing the Bolt Action Rifle... Why?: To help satisfy the obsession of owning the most accurate rifle possible.
Your rifle may not be performing to the accuracy of which it is capable. Accurizing is the process of improving the accuracy of your rifle by doing some (or all) of the modifications listed below. Even when these modifications have been completed, you still may require hand loaded ammunition to obtain the most accurate performance from your rifle, as the example below shows.
1. Bed the action
2. Work the trigger
3. Recrown the barrel
4. True all surfaces
a) Face & True Front of the Receiver
b) Re-cut inner barrel seat
c) Lap Bolt lugs & receiver locking recesses
d) True & Lap bolt face
e) Retrace Threads
5. Rechamber the barrel
Bedding the action:
The the first and most effective step in accurizing your rifle, We use various compounds in epoxy to bed the action including metal, carbon fiber, Marine Tex, and Pro-Bed. When the action is bedded, the stock and the action are rigid and the barrel floats, eliminating distortion that affects the path of the bullet.
The object is to make perfect contact in all critical areas of the receiver to the stock.
Why:
Enhances the ability to torque the receiver in place.
Greatly reduces the chance of shifting the bullet impact related to temperature and humidity changes.
The receiver stays in exactly the same position shot after shot.
Floating the Rifle Barrel:
Floating in gun talk means the rifle barrel is not touching any place in the barrel channel of the stock beyond the barrel shank. Sometimes the barrel shank is also floated.
If the fore end of the rifle stock warps or moves because of temperature or moisture changes, it will push the barrel, changing the point of impact. If the barrel is moved .001 of an inch in the stock, it would change the point of impact about 1” at 100 yards. It is very easy for a stock to move a barrel .005 to .010 of an inch.
Some rifles (a few) actually shoot better with a pressure point(s) on the barrel. Too much pressure on the barrel can string the shots left, right, or high depending on the pressure point.
Trigger Pull:
To shoot well the shooter must have as light a trigger (weight the trigger finger pulls) as he or she can handle.
The shooter must consider cold or wet weather, off hand snap shooting, etc. when making this decision.
Working the trigger reduces the force of the trigger pull and eliminates any rough spots in the trigger assembly. This provides a smooth, firm trigger pull that eliminates any "jerk" when the trigger releases.
Rechambering the barrel:
Insures that the chamber is true and perfectly aligned with the axis of the bore. It also allows you to use a different cartridge of the same bore diameter than the rifle was originally designed to use.
Recrowning the barrel:
Insures that the bullet touches the lands in the bore of the barrel uniformly as it leaves the barrel, insuring that there is no unbalanced force on the bullet that will affect the path of the bullet.
Trueing all surfaces:
Blueprinting insures that the receiver, the bolt face, and the barrel are all concentric and all faces are perpendicular to the axis of the bore, and the locking lugs mate completely and squarely in their recesses.
The machining of these components is critical because the tremendous pressure generated inside the action and barrel of the rifle will distort them, affecting the path of the bullet.
Hand Loaded Ammunition:
When the rifle has been made as accurate as possible as described above, it still may not shoot perfectly with factory ammunition because each rifle can perform best with different cartridge and bullet configurations. For example: some rifles shoot best with the bullet 0.001" off the lands while others shoot best when the bullet is 0.050" off the lands. This means you must determine the optimum configuration through trial and error, essentially "tuning" the ammunition to the rifle.