Colt had a strict spec of no more then 0.003" end shake.
To measure........
Push the cylinder to the rear and hold it there while you use a feeler gauge to measure the gap between the cylinder and rear of the barel.
Then push the cylinder forward and hold it while you gauge the gap again.
Subtract one measurement from the other and that's how much end shake it there.
With the cylinder to the rear is also the actual barrel-cylinder gap.
This should run from 0.004" to a max of 0.008" with "perfect" about 0.005".
Happily the 60's and earlier Colt's have a flange machined on the cylinder crane shaft.
To correct end shake you can install a precision washer over the shaft.
Newer cylinder without the flange cannot use a washer and the collar on the front of the cylinder has to be stretched with a special hydraulic machine then trimmed to fit.
You CANNOT drop washers into the cylinder like with S&W revolvers, that will wreck the cylinder assembly.
For Colt end shake washers buy here..........
https://www.triggershims.com/colt_revolver.php#C-OP-CYL
If this doesn't correct the spitting, you may have a spring crane and an alignment problem.
A great aid for all this is the Kuhnhausen Shop Manual on the Colt Double Action Revolvers, Volume One........
https://www.brownells.com/gear/book...ouble-action-revolvers-shop-manual--volume-i/
This shows Colt pistolsmithing to factory standards, including how to properly disassemble the cylinder without damaging it.
