I've had both a 5-screw Pre-29, and a still have a 4-screw Model 29 no dash. Both would unlock and rotate when firing regular Winchester 240gr JHP ammo, or Remington 180gr JPH ammo. The Model 29 handles 9.5gr of Unique with a 250gr Keith very well, and does not unlock, but regular .44 Magnum ammo from Wal-Mart will cause it to unlock every time. I am impressed how accurate this Model 29 is, it can cut clover leafs out of a target at 25 yards, and my friend and I were able to hit one gallon milk jugs with it at 100 yards pretty regularly.

Is it possible to put a strong bolt spring in these older 29's? Would that fix the unlocking problem?

Jared