SP101 .22LR Reliable Ignition & Reduced Power Springs?

B

BluRidgDav

New member
I have an SP101 in .22LR for teaching my wife & kids revolver skills.

The factory trigger pull is smooth, but, so heavy that they cannot cock the hammer single-action, or pull the trigger double action. I bought a reduced power spring kit to make the hammer/trigger pulls manageable, but, reliable ignition suffered.

Is there another modification that can improve ignition while using reduced power springs? Such as a built-up hammer-face, thicker transfer bar, longer firing pin, or anything else to increase the striking force onto the rim of the .22 cartridge?

Thanx, Dave.
 
Are your children very young for a revolver and your wife petite? I don't know many people who cannot cock a revolver for a SA pull.

Wolff has "shooters pak" with graduated springs so you have a chance to pick one softer than stock that will still fire. There are limits, rimfire just inherently requires a harder blow to ignite.
https://www.gunsprings.com/RUGER/SP-101/cID3/mID52/dID234

I don't think any of the mechanical fixes you name would matter unless the gun were out of spec to begin with. It would be easy to temporarily glue a shim to the hammer or transfer bar and find out. More firing pin protrusion would be touchy, too much and it will batter up the chamber rims.
 
It's the nature of the beast with the SP101. The geometry of the compact action does not lend itself well to light springs or much mechanical advantage.
And it's at its worst with .22 LR (must crush the rim) and .327 Federal (rifle primers), since they use even heavier main springs.

Smoothing up the action helps a little bit.
Trying lighter springs may help. Since that failed to satisfy you, you may want to try some different brands of ammo with the lighter spring(s).

No shims, hammer build up, transfer bar modification, or firing pin extension is really going to do anything useful. Overall, they'll just cause other problems.
 
You just bought the wrong gun for them.
Try again.

That gun doesn't do well with many women & most kids.
Denis
 
DA trigger is heavy in the SP101 .22LR. After lots of work, shooting & dryfiring, my SP101 .22LR has a smooth DA trigger under 13lbs. It was over 15lbs originally.

SA trigger is nice but cocking the hammer does take some effort.

.22LR requires a pretty good hammer hit for reliable ignition and smaller guns mean less leverage on the hammer & trigger. The combination can result in a tough DA trigger and significant hammer cocking effort.

I haven't changed the springs in mine because I want it to work with any ammo I buy. In fact part of the reason I bought a .22LR revolver is so I could use it with any ammo available without having to restrict myself to just one or two brands/loadings.
 
Thanx Guys!

I didn't buy this gun specifically to be a wife & kids trainer. I got a great deal on it "used" and then expanded it's use into other roles. But, even for this manly-man, Ruger's factory 16# hammer spring is a bit heavy to get comfortable with, in a small-framed revolver. So, like many other SP101 owners, I looked for relief using reduced-power springs, only to suffer ignition issues.

I fully understand the extra obstacles that rim-fire ammunition poses, but, I like to tinker, so, here are a couple things that I noticed about my SP101:

1. Ruger hammers are "undercut" to contact the Ruger transfer-bar. The top of the hammer face, which is the furthest forward and looks like it is the "head" of the hammer, actually only impacts the frame, not the firing pin. It is only the recessed lower face of the hammer, that strikes the transfer bar, which then has to transfer the hammer's energy to the firing pin. If the recessed face of the hammer were built-up, or some of the hammer's top protrusion were milled-down, the transfer bar would be struck more firmly.

2. The transfer bar of .22 rim-fire SP101's are milled-down at the top, making them thinner, so, that they don't transfer as much hammer force onto the firing pin. Centerfire SP101 transfer bars are not thinned down. If this area of rim-fire transfer bars were built-up, or if a center-fire SP101 transfer bar could be substituted, the firing pin would be struck more firmly.

3. Rim-fire SP101 cylinders are counter-sunk to seat the rims of rim-fire ammunition down flush with the back face of the cylinder. This may increase the distance that the firing pin must reach to hit the rim (primer) of rim-fire ammunition?

As a first step of my experiment (and easiest to reverse), I'm tempted to order a center-fire SP101 transfer bar, and do some testing . . . .

Thanx again for your help, Dave.

PS - I have close-up photos of my: hammer, transfer bar & cylinder, and will attempt to post them.
 
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Be careful about altering the transfer bar/hammer geometry--if you change the things too much, you will result in the gun damaging itself when you dryfire it.

If the firing pin strike is already making solid indents in the cartridge rims then messing with the hammer/transfer bar probably isn't advisable. If you're seeing weak indents then, as long as you're sure you know what you're doing, proceed--but with care. Go slowly and test frequently. You should be aware that Ruger won't sell you a new hammer as that is a factory fitted part.
 
Don't.
Seriously.

Just use it as it came & look for something else for your wif & kids.

People have erroneous expectations of that gun & trying to make it into something it isn't is time & money better put elsewhere.
Denis
 
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