I wouldn't waste my money on any new parts. The new spring likely won't feel any different and you'll have to bend it anyway, which is the best way to change the tension on the loading gate. Although Ruger will send you those parts for free if you call the service dept: (603) 865-2442
You should test the transfer bar safety function:
#1. TIPS FOR INSTALLING GRIP FRAMES:
Always unhook both legs of the trigger spring for reassembly, it’s easier to get the spring behind the trigger shelf.
Always leave the cyl out so you can confirm the cyl latch spring/plunger is properly aligned on the latch so it has tension on it by seeing it sticking up thru the frame, before putting in any grip frame screws. Put the cyl pin back in the frame to keep the transfer bar from hanging up on the firing pin when moving the hammer up and down.
The cyl hand spring to the left side of the hammer goes plunger first. Also, you can put a small magnet over the spring to hold it in the hole and just let the grip frame push the magnet out of the way as the grip frame ear slips into position over the hole.
Install all five screws but do not cinch them tight. Align the grip frame edges flush with the cyl frame by tapping with the butt of a plastic handled screw driver. Tighten one trigger guard screw, then front screw and then one ear screw. Then tighten them all. Check for ease of hammer movement to be sure it's not rubbing on grip frame ears.
NOTE: While you have the grip frame off, it's always good to examine the upper end of all the grip frame screws blind screw holes in the main frame (especially stainless guns) for thread shavings that weren't cleaned out from the factory and get crammed in there by the screws.
Also check the two trigger guard screw holes where they are exposed by the milling cut if your grip frame has the two projections that go into the main frame (the New Vaquero and New FT BH guns no longer have these projections and milling cuts). Almost always there will be a huge flat 'roll-over’ burr in each hole from the milling cuts that expose the holes. If they are present they generally cause the 1st 1/8" of removing those two screws to take extra effort to unscrew and can cause screws to screw in too tight and/or break off. You'll need to break off the burrs and pick them out with a dental pick or equivalent tool.
#2. AFTER CHANGING HAMMERS IN NEW MODELS:
The first thing to check is the transfer bar clearance with hammer for reliable firing pin function. When swapping hammers between two guns, it often helps To swap transfer bars as well for proper ignition and to insure the safety feature still works correctly.
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, TRANSFER BAR IS PINCHED AND 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, 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 in the next chamber to cycle 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 to let the hammer fall. The round will not fire if safety transfer bar is functioning correctly.
Factory Video - New Model Ruger Disassembly:
Factory Video - NM Reassembly (shows hammer plunger assembly too):