Adjusting Black Magic Spring Kit

[AzShooter]

After installing a Black Magic Spring Kit in a revolver what is the best way to get the lightest reliable trigger pull?

Do you just loosen the strain screw? How much?

Do you do the owee test, putting your finger on the hammer shield, let the hammer fall and if it hurts you have the right tention?

If using a scale how many oz of hammer fall do you need. Using Federal Small Pistol Primers.

[alecmc]

After installing a Black Magic Spring Kit in a revolver what is the best way to get the lightest reliable trigger pull?

Do you just loosen the strain screw? How much?

Do you do the owee test, putting your finger on the hammer shield, let the hammer fall and if it hurts you have the right tention?

If using a scale how many oz of hammer fall do you need. Using Federal Small Pistol Primers.

That's funny.

Yes, you adjust the strain screw tension to the desired hammer weight. I dont measure hammer tension, some do the pencil test , or measure the weight - ( 36-40 oz rings a bell? ) I personally just adjust the strain screw until it lights everything off, and then give it an extra little bit of turn and lock tite.

[bountyhunter]

After installing a Black Magic Spring Kit in a revolver what is the best way to get the lightest reliable trigger pull?

Do you just loosen the strain screw? How much?

Do you do the owee test, putting your finger on the hammer shield, let the hammer fall and if it hurts you have the right tention?

If using a scale how many oz of hammer fall do you need. Using Federal Small Pistol Primers.

That's funny.

Yes, you adjust the strain screw tension to the desired hammer weight. I dont measure hammer tension, some do the pencil test , or measure the weight - ( 36-40 oz rings a bell? ) I personally just adjust the strain screw until it lights everything off, and then give it an extra little bit of turn and lock tite.

Running the strain screw a little out is frowned upon at this forum...... which is to say I basically do the same thing. I adjust main spring force (bend it) until it just lights everything well on DA pulls with the strain screw 1/4T out from bottomed, and I loctite it there. I keep that extra 1/4 available in case I hit some hard primers at a shoot and need a little extra pop.

Edited January 20, 2016 by bountyhunter

[alecmc]

I've never really had problems with the strain screw loosening up, I've used both purple and blue lock tight, i know plenty of other shooters that follow the same practice.

This is another way of going about it, which I think is pretty damn cool

( photo taken from MOJO CUSTOM GUNS )

[Jim Watson]

There used to be a set of screws sold by Brownell's for that setup, I think made by Ron Power.

Teddy Jacobson sold a strain screw with a beveled tip to click into the Wolff groove.

No matter what the Internet Experts say, people WILL use the strain screw to tweak the action and you had just as well plan for it.

[pskys2]

Make sure Revolver is empty, cock hammer, put a trigger pull scale with the hook between the hammer and frame, release the hammer and take note of the ounces it measures while keeping the hammer from going past the half way point.

It varies by gun due to end shake, hammer weight, firing pin and about anything else that can cushion or affect the hammer fall.

For my 625 PC it takes about 48 ounces with my 627 PC it takes 38 ounces.

You can short term back out the strain screw, but it is prone to loosening if not secured. I like the idea of a set screw, just never did it.

[Toolguy]

If you want to lighten the mainspring and keep the strain screw tight, you can bend the spring so the hammer hooks start further forward. The more bend, the less spring tension. The more straight, the more tension. I think it works best by having a gradual bend in the middle as opposed to a sharp bend at the end or somewhere else.

[9146gt]

I've never really had problems with the strain screw loosening up, I've used both purple and blue lock tight, i know plenty of other shooters that follow the same practice.

This is another way of going about it, which I think is pretty damn cool

( photo taken from MOJO CUSTOM GUNS )

I have seen that mod on PPC guns that Joe had built in the 80's

Tom

[pete627]

I just use a hex screw ... (with one of those nylon patch thingies in the threads ... McMaster Carr) ... along with blue loctite and have never had a problem either (with them loosening up).

I have one of those little Ron Power kits to put a lock screw in ... (drill up from the bottom) ... and the original mainspring screws that I had planned on shortening to exactly the right length when I got done with these guns ... BUT ... I never did either and they haven't loosened up (that I can tell).

The 627 has accumulated over 5K rounds since it's last adjustment and the model 10 only 2K (cause I got tired of Classic pretty quick and haven't gotten back to it yet).

When I "was" making more frequent re-adjustments initially ... I just made sure I put a fresh coating of loctite on before screwing them back in. Since they have stayed stable I just have been lazy and not gotten back to do anything more permanent.

[seanc]

If you want to lighten the mainspring and keep the strain screw tight, you can bend the spring so the hammer hooks start further forward. The more bend, the less spring tension. The more straight, the more tension. I think it works best by having a gradual bend in the middle as opposed to a sharp bend at the end or somewhere else.

Can also just shorten the strain screw?

[Toolguy]

You can, but that makes the spring sit up taller, making the hammer harder to cock.

[PatJones]

As toolguy said, it will cause knuckling. You really need to to both, bend and shorten the screw.

[pskys2]

Depends, it is a balancing act. But if you're sitting at say 48 ounce hammer fall and a 6 1/2 lb action with a good feel, you will probably be ok with shortening the strain screw to get say a 36 ounce hammer fall and lightening the rebound spring to get a 5 1/2 lbs action.

You will know right away if you're knuckling as the action will get real screwy.

What I've done is get close to what I want in hammer fall weight (usually about 6 ounces more than I'm hoping will work) by bending the main spring. Then back the strain screw out until I get misfires and back in until it's reliable again. Then measure and cut a strain screw to match. I always keep the original as is, just in case, and do a third that I'll whittle down gradually to what I want.

That way if in the middle of a match I have an issue I can go back to what I had that I know worked, or at worst case to what I had originally which is usually 25% more than what the minimum was.

Another quick fix is to keep a used cleaned out primer cup in your bag and if you have issues develop you put the primer cup between the strain screw and the main spring.

If you go too far and the main spring knuckles you will know it.