I'm not surprized your DA pull is off the chart with the mainspring at full power. My recently purchased S&W's ALL had DA trigger weights between 12 and 12.5 lbs. with the factory mainspring at full power.

What I've been doing to tune the triggers in my guns is shimming the strain screw OUT. Since nobody makes these shims I've been fabricating mine out of shim stock. Start by drilling the shim stock with a 0.147 inch diameter drill and trim them into small squares with some scissors. Then I take a Diamond burr in a Dremel and shape the outer diameter to a 0.218 inch diameter. Now a couple of tips if you want to try making these shims. First, put the shim stock between a couple of pieces of hardwood when you are drilling it, that will keep the shim stock flat and allow you do drill a clean hole. Second, you'll need some pliers that can firmly hold shim steel as thin as 0.005 inch, I had to do a bit of dressing of the jaws on a cheap pair of pliers so they would hold that thin steel tight. REading glasses are also a real help and I'll warn you that you can only get a small part of the OD with each "bite" of the pliers. Take your time and you'll get there. As for where to get diamond burrs, I got mine from a local tool supply shop, Production Tool, and they are on the Net.

Now some specifics on shimming. First, make up your shims using 0.005, 0.010, and 0.015 shim stock. Then I would suggest that you start on 2 of the 0.010 inch thick shims and check to see where your DA trigger weight breaks. My experience is that this will put you into the 9.5 lbs. to 10.0 lbs. range, which is as light as I would recomend going with the factory firing pin. I expect that you'll then find that your Single Action trigger is breaking just a tick over 3 lbs.

If you replace the factory firing pin with one from Cylinder and Slide I would recomend you set the DA trigger to 8.5 lbs and all that good. This will provide 100% ignition reliability with all the ammo brands I've been able to find locally without running the risk of a pierced primer.

Finally, I would recomend that you NOT stone the single action sear on your trigger. Simply shooting your 460 will do any needed smoothing to the single action sear surfaces and the sear step on the hammer is microscopic. This means that if you dust the sear on the trigger too aggressively that tip will tend to round over and then you'll be looking for both a new hammer and trigger because Pushoff generally pukes out the sear on the hammer quickly. I have a personal rule of NOT fooling with my single action sears because getting this interface wrong means buying new parts.

I've also avoided doing anything with my double action sears. However the reason for this is simply because I've found that simply shooting the gun cleans these surfaces up as well as I could do with a stone. That's one plus for the MIM parts used in our newer revolvers, because there properties cause them to "wear in" very very nicely.

PS; I'm looking forward to your writeup on your model 60. Everything I read indicates that the J frames smooth up well but if you try and take the double action weight below about 10.5 lbs. you end up with misfire issues.