What does it take to install "Half Cock" in my New Vaquero's?

[Steel Striker]

My title says it all.  Which direction shall I consider & what can I do for myself?  Thanks.

[Coffinmaker]

It depends on what you want to accomplish by going off "half cocked."  Half cock by itself is fairly simple....  Buy a hammer that has been modified with a half cock ledge and swap em out.  This will be a half cock "ledge" and will catch the hammer if you fail to fully cock it and
wish to avoid going "around the world."  It is NOT a half cock "notch" and it is NOT safe for loading purposes.

True Half Cock will require the hammer be welded up, re-machined for the half cock notch and the trigger will have to be re-profiled to
fit in said "notch."  Somewhat more complicated.  Extra fitting and fettling required.  Safe for loading purposes.

If your goal is to eliminate the Transfer Bar ....... There will be more welding and re-machining required.

I don't personally see any reason to do any of the above ....... unless your determined to become one of the top 5% of CAS shooters
and you just have to have your Ruger "feel" like a Colt.  Which it won't anyway.  So ....... unless your fairly accomplished at Ruger Problem Solving 101 ....... ship it off to someone who is very good at Ruger Problem Solving graduate work.

Coffinmaker

[Steel Striker]

Coffinmaker;  Details much appreciated. 

Yes, I'm seeking to prevent chasing an unfired round in the cylinder.  In my haste to increase speed, I occasionally 'short stroke' the hammer.  I'd MUCH rather recock than get all fumbled up when it don't go BOOM!

I will be mindful that it's not a true safety feature, as I cannot afford $250+/gun.  This is my 3rd season.  All part of the learning process, eh.

Wally

[Pettifogger]

This is your basic half-cock kit.  It still uses the transfer bar (modified just a bit) but gives the Ruger the Colt feel.  Well made and new parts.  Cut and chop and rewelds cost as much or more and have to be fitted by the person doing the cutting and welding.  These are usually pretty much drop in but I have had some that took a bit of work to get everything to work correctly.  I don't know of anyone else that makes half-cock kits.  The next step is to go full boat and get a short stroke.

http://www.brownells.com/handgun-parts/trigger-group-parts/hammer-parts/hammers/ruger-sa-half-cock-hammer-trigger-kit-prod9845.aspx

[Mustang Gregg]

I bought a pair of full size K-Bisley Vaqueros that has been short-stroked. 
Their hammers are welded and their transfer bars have been gutted.
I don't really like the multiple click hammers.
I don't think I would have spent the $$$ to have it done. 

I think a reversing pawl would be a better mod. 

My opinion only.  Your mileage may vary.
Mustang Gregg

[Good Troy]

I have a brace of Cimarron revolvers (half-cock) and another brace of Ruger NMV.  It seems that the only time I ever "short stroke" is with the NMV.  I guess it is Old man Murphy looking over my shoulder!