In some intances this is possible, but its better to err on the side of safety.
The Summaron does have a full barrel coupler.
Its not the coupler which causes the trouble, but its the notch in its mount. If this notch lines up (in most cases with FED or Zorki, in cameras with correctly oriented mounts, it would) with the sensor tip, it could spell trouble.
The sensor
will not catch if its orientation isn't too steep. In some cases the sensor will be oriented with its gently curved side facing out. How the sensor is oriented
depends on the construction of the camera's rangefinder.
The sensor tip's orientation determines the ability of the rangefinder to measure accurately at close distances- it cannot just be arbitrarily positioned to accomodate just any lens. Here is an example of one camera whose sensor tip is gently sloped- and it can accomodate the Summaron:
The FED-1 used a tiny tear-drop sensor tip. Its shape is very conducive for catching and hooking into things. Just imagine how nicely it will go into the notch of the Summaron 35:
And here is an example where the rangefinder demanded that the sensor tip be oriented so that its sensor tip be sharply sloped.
Yes, the Summaron got caught in this one. Lens removal wasn't much of an incident since the camera, a FED-2, had an opening back. The shutter was opened and the RF arm was pulled back to allow the lens to be unscrewed from the mount. A caught lens, if unscrewed with some force will probably turn.
It will probably cause the RF sensor tip to move a bit. The sensor tip is pivoted so it can be moved for adjustments.
But once it moves, its calibration is upset and will need recalibration.