Roylt,
Great job, I can tell that you're having fun! I have some project guns that are never done. I'll do something new on a new gun and then go back and do the same thing on previous project guns. It's a new sickness I have. But all fun.
1.) Just as medicdave posted: The grip projections were designed for extra strength when all Ruger Grip frames were aluminum alloy, up until 1959. Now Ruger model grips frames are roughly half steel and the other alloy on blue guns and of course all stainless steel guns have steel GFs. So starting in 2005 with the 50th anniversary models and the New Vaqueros, which both only use steel grip frames on all blue and SS guns, the projections were unneeded, took extra machining, and were an added cost.
So special editions using birdshead grips frames which can be almost any regular production model, had projections from the mid 1990s when first offered until 2005. After 2005 BH GFs have them deleted. Even if the main frame has the milling cuts for the projections, you can use a steel grip frame w/o them.
2.) Hammer swaps seldom need fitting to the transfer bar. Only if ignition is unreliable or the safety bar function doesn't work. Here's my tutorial for checking all hammers after a swap for both issues (one of which you already verified):
AFTER CHANGING HAMMERS in New Model Rugers, the first thing to check is the transfer bar clearance with hammer for reliable firing pin function.
TO TEST HAMMER/TRANSFER BAR FOR MISS-FIRES:
With hammer fully cocked, press on the transfer bar to extend the firing pin and observe how far thru the recoil shield it protrudes. Now keep the trigger pulled back, drop the hammer and observe the firing pin again. If firing pin protrudes the same amount, you're good to go. If it doesn't protrude the same amount, you need to remove just enough metal from the top face of the hammer nose so the transfer bar is pushed tight against the firing pin and the frame. If you remove too much, the transfer bar will not perform its safety function and will be pinched. Also make sure hammer has no friction or contact with grip frame ears around its base to slow its fall and you may have miss-fires; another potential issue when making hammer changes.
IF TRIGGER DOESN"T RETURN, SAFETY IS NOT WORKING:
If the transfer bar is hanging up under the hammer face, since it's connected to the trigger, it prevents the trigger from returning. The transfer bar is slightly too thick. If both ends of the trigger return spring are connected (under the grips), or even if you have only one leg of the spring connected it should pull down the transfer bar if it's the correct thickness. When this happens, the transfer bar safety function will not work. If the gun were dropped, and a live round in the chamber under the hammer will fire.
This is not uncommon however, and it's a very simple fix. File the second step of the hammer face, counting from the top, just a bit until the bar no longer hangs up. Don't take too much off or you'll have miss-fires. If that happens file a little more off the top step of the hammer.
IF YOU HAD TO MODIFY HAMMER NOSE:
At the range, double check the safety function by loading a live round under the hammer, point down range, cock the hammer, hold with thumb, release the trigger to uncock the hammer, take finger off trigger and release your thumb so the hammer falls. The round will not fire if safety transfer bar is functioning correctly.
Jim