I bought a new (to me) python yesterday that is in fairly nice shape, with almost no turn line.
I got it home and dry fired it a few time and am somewhat disappointed. The trigger is heavy both in da and sa. It is not to compare with any of my smiths. Serial # shows to be made in 1981.
With a used gun, there can be problems caused by a previous owner. A bad single action trigger in the Python doesn't sound good. The Python is famed for it's great SA trigger pull.
First, understand that the old Colt action as used in the Python has a totally different feel than the S&W action.
Many people have trouble getting the hang of the Colt's double action feel and don't like it at first. It "stacks" and gets heavier as the trigger is pulled. This is normal.
Second, I'd recommend cleaning the action and applying fresh lube.
DO NOT attempt to remove the side plate or cylinder unless you have the correct Brownell's gunsmith screwdriver bits and know EXACTLY how to do it.
Pythons are too expensive to cause damage attempting to disassemble without having the right tools and knowing the quirks of the Colt's.
Often the problem is no more than a fouled action with dried up or dirty lube.
Choices here are to remove the grips and use a gun scrubber spray to blast out the action, dry thoroughly, then spray in a good gun lubricant.
Make sure the problem isn't a gummed up and sticky cylinder by trying the action with the cylinder open.
Another choice is to do something a Python owner ought to do anyway, and that's to buy the Jerry Kuhnhausen shop manual on the older Colt's actioned guns.
This is a shop manual written for the use of gunsmithing students and covers EVERYTHING on the older Colt's including proper disassembly, how to trouble shoot problems, how to install parts, how to improve the trigger in SA and DA, and how to determine if the very picky Colt action is in proper adjustment and timing.
The info on timing is itself worth the price just so you know your Colt is working correctly.
Another choice if you feel uncomfortable with the above, or you just want to know for certain your Python is Okay, would be to send it in to Colt for a factory check up.
While they have it they'll give it a total cleaning and correct any problems.
If you want the absolute best from you Python, Colt can do a factory action job to give it the best trigger possible.
Last time I checked, Colt offered two levels of trigger work. The "Service" job improves the trigger but it will work with any .357 ammo.
The "Target" job is as good as it gets, but the gun can only be used with .38 Special target ammo, since the action will be too light to give reliable ignition with the harder primers used in Magnum ammo.
Bottom line, BE CAREFUL.
Pythons are simply too valuable to risk damage caused by improper repair or cleaning attempts. I don't recommend trusting any local gunsmiths, because almost none of them "understand" the old Colt action or have the special tools needed to work on them.
Take a Python to a local and you stand a high chance of getting a gun back with damage that will cost even more to correct. Taking a Python to most locals is like taking a Ferrari to the corner gas station for major work.
Last, even if you have no intentions of ever working on the gun, buy the shop manual. It's just good to know if your Python has a problem that needs attention.
Colt triggers are different. If you're not used to them it can take some practice, at least on the double action. Single should be fine, indeed most old Colts are excellent.