Whatever you do to a Browning M1885 don't modify the action in any way. I recently bought a used Browning BPCR for resale. The 1st thing I do on all used Browning's is to fully disassemble the action to check for wear and for complete cleaning. After reassembly, the hammer would hang up in the 1/2 cock position most of the time when attempting to fire the rifle. It seemed fine the one time I dry fired it prior to disassembly, I worked on the rifle for at least two hours trying to figure out what was wrong. All the parts seemed to be working correctly and nothing appeared to be worn. Finally it dawned on me the two mainsprings did not look right. One end was different than the other on both. It turns out the previous owner had shortened the springs by cutting off between 1/8" & 3/16", most likely in an attempt to lighten the trigger pull. Fortunately I had a couple of new springs in stock for a comparison and for replacement.
The firing function of the Browning 1885 action relies on smooth and rapid movement of the hammer and hammer sear. If the hammer is slowed down appreciably, due to a modification, dirt, etc., it will likely catch in the half-cock position. If the hammer rotation is slowed, it allows sufficient time for the hammer sear to return to its resting position and the sear step on the hammer will catch the half-cock step on the hammer sear.
Wayne
