mnzrxer
05-01-2010, 12:07 AM
In February I was a very happy new owner of a Colt Diamondback 38 Special. I had to buy two whole boxes of factory ammo for it while I waited for dies and a boolit mould to arrive (a couple of days can sure seem like forever sometimes). After a couple hundred rounds I started having failures to fire in double action. Eventually this got to the point of only 1 or 2 rounds in a cylinder actually going off on the first strike. Cocking the hammer and firing single action resulted in no failures, so I had to dig in and figure out what was going on.
I found in single action the hammer was back maybe 1/4" further than when the trigger released it in double action. I also noticed when cocked the V mainspring or hammer spring was touching the two legs together about 1/2" from the tight bend at the bottom of the V. So I figured the spring was weak and in need of replacement. Unfortunately I must not be the first person to need this spring as I could not find one.
In the past I had read a little bit about making springs and while browsing some catalogs I saw spring stock for making flat springs. I couldn't find exactly the right thickness of stock, but ordered an assortment because I'm sure somewhere down the road it will come in handy.
Once I had my new spring stock in hand I didn't feel I had much to lose in trying to fix the original spring, so I removed it and set to work. Before doing anything to the spring I put it on my scanner and made a copy of the side profile I could reference if things didn't work out on the first go 'round. On this copy I also noted important measurements such as the width and thickness, distance across the open end of the spring, etc. Once I felt I had enough info to recreate the geometry of the spring if I really screwed it up I moved on to actually trying to revive it.
First, I heated it cherry red and allowed it to air cool to anneal it. This allowed the spring to be re-bent. I opened up the spring by bending it at the bottom of the V. I didn't want to go too far and make the trigger pull to heavy, but I wanted to make sure there would be enough tension to get the double action working again. This was just a guess and I figured I could try again if it didn't work. Next I heated the spring cherry red again and quenched it in oil to harden it. For the next step, tempering, I had found a number of methods and many seemed to rely on guessing the temperature of the steel based on its color. I know this could work, but I wanted something more consistent and harder to screw up. So, I fired up the lead pot. I had found info stating this type of spring should be tempered at about 600 F or a dark blue color. My pot ended up at 625 F on its lowest setting (according to my Lyman thermometer). I threw the spring in and pushed it down into the lead to make sure it heated as evenly as possible.
When I pulled the spring out of the lead I was happy to see a dark blue hue to the steel. It felt nice and springy again, too. After installation and a function check I went out and shot what ammo I had (only 25 rounds). Happily every round fired on the first strike in double action again. I now have another 100 rounds waiting to test the revived spring. I will likely still make at least one more spring from the stock I bought just to have on hand.
Overall the process was quite easy and having the lead pot to temper the spring made that part really pretty foolproof. Hopefully this info can help someone in a similar situation.
I found in single action the hammer was back maybe 1/4" further than when the trigger released it in double action. I also noticed when cocked the V mainspring or hammer spring was touching the two legs together about 1/2" from the tight bend at the bottom of the V. So I figured the spring was weak and in need of replacement. Unfortunately I must not be the first person to need this spring as I could not find one.
In the past I had read a little bit about making springs and while browsing some catalogs I saw spring stock for making flat springs. I couldn't find exactly the right thickness of stock, but ordered an assortment because I'm sure somewhere down the road it will come in handy.
Once I had my new spring stock in hand I didn't feel I had much to lose in trying to fix the original spring, so I removed it and set to work. Before doing anything to the spring I put it on my scanner and made a copy of the side profile I could reference if things didn't work out on the first go 'round. On this copy I also noted important measurements such as the width and thickness, distance across the open end of the spring, etc. Once I felt I had enough info to recreate the geometry of the spring if I really screwed it up I moved on to actually trying to revive it.
First, I heated it cherry red and allowed it to air cool to anneal it. This allowed the spring to be re-bent. I opened up the spring by bending it at the bottom of the V. I didn't want to go too far and make the trigger pull to heavy, but I wanted to make sure there would be enough tension to get the double action working again. This was just a guess and I figured I could try again if it didn't work. Next I heated the spring cherry red again and quenched it in oil to harden it. For the next step, tempering, I had found a number of methods and many seemed to rely on guessing the temperature of the steel based on its color. I know this could work, but I wanted something more consistent and harder to screw up. So, I fired up the lead pot. I had found info stating this type of spring should be tempered at about 600 F or a dark blue color. My pot ended up at 625 F on its lowest setting (according to my Lyman thermometer). I threw the spring in and pushed it down into the lead to make sure it heated as evenly as possible.
When I pulled the spring out of the lead I was happy to see a dark blue hue to the steel. It felt nice and springy again, too. After installation and a function check I went out and shot what ammo I had (only 25 rounds). Happily every round fired on the first strike in double action again. I now have another 100 rounds waiting to test the revived spring. I will likely still make at least one more spring from the stock I bought just to have on hand.
Overall the process was quite easy and having the lead pot to temper the spring made that part really pretty foolproof. Hopefully this info can help someone in a similar situation.