Anyone here that can explain the art of tuning a sear spring???
I already can do the rest on a 1911 trigger job (stoning, polishing, etc.) but I've always had to rely on a sear spring tuned by a local 'smith. I'd like to do that myself when I swap out the hammer, sear, disconnector (all Extreme Engineering), trigger, strut, mainspring, safeties, etc. on one of my kimbers that I'm setting up for USPSA single-stack division.
Any info is greatly appreciated!!!!!
Adjusting the 1911 sear spring
I have approximately 20 years experience working on the 1911 pistol & think i can answer your question. Please disregard the cap letters. I am legally blind due to a series of mini-strokes which have affected my ability to see. I can no longer drive a vehicle & depend upon my family and friends to take me where i need to go. Now to your question !!!!!
I personal favorite spring for this application is the "clark 4-finger" spring, as the individual leafs are readily adjustable for their design purpose.
Holding the sear spring in front of you, with the longest one to the left, they are numbered as follows:
Original design: 1. Sear 2. Disconnector / trigger bow 3. Grip safety
clark design: 1. Sear 2. Disconnector 3. Trigger bow 4. Grip safety
prepping the spring contact surfaces: The underside of leafs 1, 2, & 3 need to be polished where they contact the above mentioned parts. Polish the tips with red crocus cloth wrapped around a wooden popsicle stick & polish along the length of the spring until very smooth & bright. Polish area with a small dab maas or flitz metal polish on a soft cloth & rub area briskly. Turn cloth over & buff off the black junk that comes off. Better yet, use a dremel tool, round felt bob, & one of the above mentioned polishing pastes. Now the sear spring is ready for a trial installation.
With grip safety off the frame, flip the hammer strut up & forward. Insert spring into frame. Inspect under bright light to insure the tips of the leafs are contacting the proper parts. Slide mainspring housing into the frame far enough to line up the frame hole & housing retainer pin---no need to insert pin !!!!!
Function test #1----install grip safety in proper position & secure with just the thumb safety pivot pin. Depress grip safety, then release. Grip safety should pop up quickly & feel slightly firm on the depress. If it does not pop up smartly, remove sear spring, hold spring in lt hand, grasp leaf #3 (original spring) or #4 (clark spring) with needle nose pliers, grasping the leaf slightly behind the tip, gently apply pressure to bend the leaf gently back toward you. Install spring again & repeat the test, until the grip safety pops up quickly when released. When satisfied with your efforts, remove grip safety from frame.
Funtion test #2-----the leaf tip touching the end of the trigger bow (clark spring) exerts continuous pressure against the trigger keeping it pushed forward into the front of the frame. Looking inside the frame, press the trigger backwards, then release. The trigger should briskly return to the forward position. If not, then gently bend the spring leaf away from you to increase the contact pressure against the trigger.
Function test #3----this leaf touches the lower angle end of the disconnector & exerts pressure to push the opposite tip of the disconnector through the top of the frame rail. Look for the tip which protrudes from the top of the frame rail. Push the tip downward with your fingertip or wooden dowel, then release the downward pressure. The tip should pop back up quickly. If it does not, then visually inspect again to insure it is touching the lower angled end of the disconnector. If ok, then the tension needs to be increased. Bend leaf gently away from you, install & repeat until tip pops up quickly.
Final function test #4----the longest leaf presses against the sear. Hold pistol in shooting hand. Use thumb of opposite hand to press against the back of the hammer applying firm pressure as the hammer spring would do. Press trigger toward you & hammer should crisply spring forward. If release feels too light, then gently bend spring leaf away from you just a little bit & try again. Repeat until release pressure feels correct.
Overall final function & safety test: Reassemble all parts into frame. Thumb cock hammer to full cock position. Insert a wooden pencil eraser end between the hammer face & the frame. Move thumb safety to down position, depress grip safety with shooting hand & press trigger. If trigger pull feels too easy, tension the sear leaf slightly more away from you. Assemble pistol & try again. Confirm trigger pressure with a trigger pull gauge for about 4 to 4.5 pounds.
Assemble slide on frame & if possible, fire live rounds to confirm hammer stays in full cock position between each shot. If shooting not possible, remove magazine, pull slide fully to rear of frame & release like shooting a sling shot---do only 2 times. If hammer remains at full cock, congratulate yourself on a job well done !!!