September 23, 2010
By David Tubb
In the search for the ultimate in match rifle accuracy, faster is better.
By David Tubb
Tubb's redesigned bolt for the Remington 700 is all about reducing lock time and increasing accuracy. It incorporates a lightweight firing pin, smaller firing pin hole, smaller ejector and a more efficient extractor design.
The Remington 700 action is popular and in use by many competitive shooters, as well as tactical professionals, and for years I've been striving to make it better.
It's unrealistic to criticize a reasonably priced factory rifle for not including some of the re-engineered system components I and others have come up with.
The ignition system is a good example. I am adamant about attaining an extremely fast lock time (the time between trigger break and primer ignition).
Shooting offhand, for instance, there's always more movement than we want. I believe that there is a connection between rifle accuracy and lock time, and without a doubt there is a connection between lock time and score when shooting at targets on a windy day.
So every time we can reduce the time between trigger break and cartridge ignition, we have effectively improved accuracy. If the shot fires closer to the time the sight or crosshairs are on target, then the bullet will hit nearer to the position of the sight or crosshairs. Can't ask for more than that.
So the first product I created many years ago was the SpeedLock lightweight firing pin for the 700. After that, and realizing that no amount of custom gunsmithing could accomplish what a clean sheet of paper could, I came up with a new, complete bolt assembly.
The components included an efficient, small extractor; a smaller firing pin hole diameter; a small diameter ejector; precision manufacturing techniques that eliminate the need for truing and squaring; and, of course, fast lock-time. I also wanted to offer interchangeable bolt knobs so shooters could change them to suit their needs.
I incorporated every lock-time reduction trick I know — light-weight aluminum bolt shroud, lightened cocking piece, chrome silicon spring and a SpeedLock firing pin with an 0.062-inch diameter pin tip to go along with the smaller hole diameter into this part — and it provides a little better than 40 percent faster ignition over standard bolts. That means the bullet leaves the muzzle before the firing pin tip on a stock 700 action has even hit the primer. That's big.
Reducing the firing pin hole diameter to 0.065 inches (a Remington bolt's firing pin hole is normally 0.078) also makes for far fewer pierced primers when striving to attain maximum velocities from a load. Additionally, increased striker energy is imparted onto the primer for more reliable ignition.
The reason for reducing the ejector diameter was to help minimize brass flow into the ejector hole, and with a smaller ejector plunger hole in the locking lug the bolt is slightly stronger. Remington stock size is 0.135 inch; ours measures 0.110.
The extractor design is another part I developed years ago. Shooters have long been replacing the stock Remington extractor with a Sako-style one to improve function. I believe an extractor should be as small as possible to increase the effective bolt face integrity, but it must also work 100 percent. Additionally, I increased the bolt body diameter to 0.699 inches, so that bushing the front and rear for a close fit in the action — as we often do on stock bolts — isn't necessary. Adding flutes to the bolt body decreased weight and changed its appearance. A custom rifle should look custom.