I am sitting here with my (properly functioning) R-M '51 revolver and will describe the cylinder notch location during it's operation.
The cylinder rotates clockwise (left -to- right) when viewed from the breech (hammer/grip/loading gate) end. when the hammer is full cocked there is an alignment of the upper most bolt notch (12 o-clock) (the left side/squared-flat/opposite of the tear shaped lead groove) with the left side of the hammer cutout in the frame.
If you must assist the cylinder's rotation toward the right (loading gate side), then I would tend to think that your hand is exhibiting signs of being too short.
You describe signs of the bolt dropping opposite? of the lead-in tear-shaped ramp/groove -do you not? -if so- then the cylinder is over-rotating (as just described), and you may be experiencing signs of the hand being too long (and rotating the cylinder -past- the expected bolt drop).There is also a possibility that the bolt timing is retarded, allowing the cylinder to spin past the expected stop of the bolt falling into it's cylinder notch and resulting in the symptoms portrayed by theRodDoc
I am only working with information supplied by my well-thumbed copy of Kuhnkausen's "Colt single action revolvers -A shop manual, volumes 1&2". From my experience, (and more info supplied in the Kuhnkausen book), you could also be experiencing problems with the flat spring of the hand being broken -or- weak. Then there is also a possibility that the bolt/trigger spring is problematic (cracked between legs?) -or- a combination of any of these (or some other as yet undescribed) difficiencies.
To think that ANY of the aforementioned problems are occuring to a factory-fresh cartridge firing hand gun is troubleing. You would be well advised to consider returning it for inspection and repair.
You haven't indicated whether you have done any live-fire testing of your -NEW-? revolver.
If you have NOT, then DON'T !
Until you have had the gun's operation investigated by either a trained gunsmith and/or repaired by either that professional or the factory/distributor's representative repair facility.it is just too dangerous to contemplate firing live ammunition