THE WORLD LEADER IN HIGH-PERFORMANCE PARTS FOR CROSMAN & BENJAMIN AIRGUNS
Copyright © 2015 - 2020 Magnum Gunworks, LLC ™. All rights reserved.
13XX MAGNUM ADJUSTER INSTALLATION & ADJUSTMENT
1377C, 1322C, P1377, P1322, 1300KT, PC77 & 2289G Backpacker
For maximum power, set spring tension to the minimum needed for the power level to peak at a specific number of pumps. With too much spring tension the valve will close faster causing power loss.
For the best accuracy, use the least amount of spring tension needed for the gun to fire well. This also lightens trigger pull and reduces wear on trigger group, valve and hammer components.
The small diameter of this adjuster leaves room for about two full threads of mounting-screw engagement. This is more than sufficient due to the high strength of the alloy it's made from. The screws should be snugged down firmly but not heavily torqued. A small amount of medium-strength threadlocker can be used on the first few threads of the screws. This will keep them from loosening but still be removable. We haven't had any issues with damaged threads and we've sold thousands of these adjusters since 2009. This info is included only as a precaution for those who tend to over-tighten things to an extreme.
The original Crosman screws are a poor fit and hit the threads on the adjuster knob. Alloy-steel socket screws and a spacer washer are included. The washer is needed for the longer 11/16" screw, otherwise it may hit the threads on the adjuster knob. Do not add a washer to the 1/4" screw, it's a perfect fit. Both screws require a 3/32 hex wrench which is not included.
1 ) Make sure the gun is unloaded, uncocked and empty of pressure.
Remove the rear trigger frame and rear breech screws. Remove the tube plug which is where the adjuster will mount. It usually falls or lightly ejects out if you don't hold it while removing the screws.
Install the adjuster with the threaded knob removed. Install the screws, don't tighten either until both are fully threaded in.
Place the hammer spring on the guide at the tip of the threaded adjuster knob. Make sure the spring goes into the back of the hammer as you thread the knob into the end tube plug.
If you turn the adjuster knob in too far the hammer will not pull back far enough to catch on the sear. Adjust to full spring compression with the gun cocked, stop when you feel the spring is fully compressed, do not force it further. Back the adjuster out two full turns, this is the strongest setting that works smoothly in most cases. Peak power is usually at a lower setting due to the valve stem closing faster from too much hammer spring force.
2 ) With a power adjuster, custom valve or stronger hammer spring it’s typical to have to cock the gun to get the valve to seal so it can be pressurized.
3 ) The more striker spring tension you have the harder it becomes to pull back the bolt. With a heavier spring, especially if using a power adjuster, the bolt will pull back easier with your finger hooked around the front of the handle close to the breech. If done in one quick motion the bolt will pull back smoothly. If done slow or holding the handle further away from the breech the bolt may tend to bind or work rough.