My, that's a beautiful looking handgun.
I suspect as others do that the chambers are factory and for the 44special.
The fact that a heavily roll crimped 44mag case w/a lead bullet would drop in does not necessarily sound any alarm.
Is the roll crimped case a factory round, or a reload? If a reload, do you know if the case was ever trimmed,,ever?
Old rounds aren't much use as gauges.
The factory loads are better to gauge by. At least some consistency. Even then the specs vary from mfg to mfg as any reloader knows.
But the fact that none of the Factory jacketed loaded rounds would chamber, and they all seated to approx the same depth would tell me that the chambers are the same depth.
Simple examination will tell you if they've been recut/lengthened. The reamer marks when the operation is done will just not match up with the original and the lengthened section can usually be spotted.
Unless a very competent workman with a nasty habit of touching up details, those reamer and even followup chamber polishing marks will show,
It certainly doesn't look like any such work done on the three that can be seen from the front in the one pic.
Are there any bright marks encircling the chambers on the rear face of the cylinder?
If the chambers are deepened, the reamer goes in and cuts but the depth is generally controlled simply by the rim cutter portion of the that reamer as it comes in contact with the rear face of the cylinder.
That simple very light contact will leave a bright mark in the bluing,,at least somewhere around some, all or maybe onlyone of the chambers. But it'd be very difficult to do the job w/o touching that surface w/the reamer rim cutting edge and not leave an imprint.
A careful set up on a mill w/a depth stop would do it w/o marking the rear face if done correctly. But normally these chamber lengthening jobs are a reamer, a T handle and squirt of favorite lube juice while the cylinder is in the bench vise.
??--Wouldn't many/most(all?) common factory loaded Jacketed 44Magnum rounds if seated completely in the cylinder of these 2nd Models leave the bullet hanging at least a little bit out the front of the cylinder?