View Full Version : revolver term: "tight lock up"??

04-05-2010, 9:15 PM
When looking at used revolvers, you often hear the term "tight lock" (or something to that effect). What does it mean and how does one determine the wear status of a revolver?

04-05-2010, 10:08 PM
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04-05-2010, 10:09 PM
Refers to how much or how little movement of the cylinder there is.
A cylinder that "locks up tight" has little or no movement.
Cylinders can have play front-to-back, up and down or side-to-side or all three.
A slight amount of movement is normal, if totally rigid, nothing would move.
Note that some revolvers only lock-up completely when the trigger is held back after the hammer is dropped.

In a used revolver, I look for no crane movement at all; almost no cylinder side-to-side or up-and-down play, a few thousands of an inch worth of front-to-back play is OK.
The gap at the front of the cylinder to the rear of the barrel mouth should not be much over .006".

The other thing to check is if the cylinder chamber holes line up with the barrel hole.
Usually this is checked by dropping a precisely sized "range rod" down the barrel and see if it goes right into the cylinder holes...if not (rod bumps the edges of the holes or won't go in), the cylinder is not locking up in the correct position and the action needs repairs.

04-05-2010, 10:34 PM
Thank you, very helpful.

04-06-2010, 7:46 AM
There is a distinct difference on the lock up of a Colt vs a Smith. The Colt uses a two stage hand & Smith uses a one stage hand.

On a Smith, only the top of the hand moves the ratchet and cylinder in one single stroke. Lock up is achieved horizontally - the thickness of the hand, the fitting of the ratchet and its relationship to the hand & to some extent the cylinder bolt all contribute to side to side lock up. Smith sells oversized hands and cylinder bolts as replacement parts.

Colt uses a two stage hand with two distinct "steps". The top step of the hand starts the cylinder moving by lifting up the ratchet and moving past, the 2nd stage (step) then picks up the ratchet and if all is timed well, exerts upward pressure on the ratchet as the trigger pull is completed. So the Colt hand acts on the ratchet vertically and continuously and in doing so pushes the cylinder against the bolt to positively hold the cylinder in place. So far as I know, Colt doesn't sell oversized hands (per se) or cylinder bolts because the hands always require a good deal of fitting. The thickness of the bolt isn't all that important because pressure exerted by the hand on the cylinder keeps it pressed against the right side of the cylinder via the cylinder notches.

If you open the cylinder of a Colt - older Python, D frame type, not the Lawman, MkIII type - you'll readily see the ratchet on the rear of the cylinder. Since the Colt can be cocked with the cylinder open you can see the hand move up and IIRC see the top and 2nd stage as it moves up. Alot easier to see than to describe.

04-06-2010, 8:42 AM
Right...Colt DAs and a few others (including most early Charter Arms) want to do "totally tight lockup", zero rotational play.

Which works great so long as the alignment is right - better accuracy. If however it's locked tight in a mis-aligned direction, the gun will try and tear itself apart with every shot.

The Ruger/S&W/Taurus system uses some "rotational slop". This costs a bit of accuracy (not much!) and allows the bullet to create the final bore alignment at the time of firing. This system is more tolerant of wear.

"Endshake" is something else, that's when the cylinder moves forward and backwards in relation to the barrel. A tiny amount is OK, any more than "fractionally noticeable" means the cylinder becomes a battering ram on firing, stretching the frame apart. Ideally it should be eliminated as soon as you spot it, esp. on something with an aluminum frame or really major power.