I bought a used Uberti 1885 rifle in 38-55 with a single set trigger.  I'm reading that some folks say the hammer will only come to half cock when the lever is lowered and others say it will come to full cock. Mine comes to full cock..... But today I experienced a AD as I closed the lever on a live round. Not good! I adjusted the trigger setting screw in and out and it made no improvement. Using a spent case and using the lever fast and slow, at times the hammer would follow the loading block down, and at worse the hammer would AD. 

I'm trying to find out if the previous owner might have had someone modify the hammer/trigger to go to full cock or is this the way it came from the factory. I have a couple other ORIGINAL  low walls and high walls and they all come to half cock when the lever is lowered.

What say the board.....

My brother bought one a few years ago new, 45-90 with double triggers and it only went to half cock when the lever was dropped and then closed.

My original coil spring closes to full cock.

The development of the coil spring action was designed for the take down model.  About the same time, Charles Winder was a proponent of youth shooting activities and talked Winchester into making the Winchester highwall musket and the Winder musket in 22 caliber. He thought it would be safer for the youth to have a hammer that lowered to half cock so many of the muskets have a different fly in them. You can find coil spring actions with both styles.

My Meacham DST High Wall is a coil spring action and it closes on full cock. 

My Browning BPCR ST High Wall is a strut spring action and closes on full cock.

My Winchester 1885 ST High Wall made in 1894 is a flat spring action and also closes on full cock.

I don't own one, but after talking with a Uberti rep, their 1885 highwall clones are supposed to close on the half cock. Perhaps their attorneys advised them to do so?

I researched this in an attempt to find the fastest single shot action rifle made before 1900. A Uberti would've made an affordable price point consideration to compete with, but their action design still had the shooter manually cocking the hammer which lost precious time in a speed match. I decided to use the Browning action at first, and have gone to the antique action now for my speed match action rifle of choice. 

But I'd certainly be suspect that someone has tinkered with the action considering your description of a Uberti 1885 action which closes on full cock which sometimes accidentally discharges.

Best of luck, and keep that thing pointed in a safe direction

We’re talking apples and oranges and cranberries here!  The OP asked about the Uberti copy of the high wall, not the original or one of the American copies.  Each variation has it own peculiarities and needs to be understood as such. 

OP, if you feel comfortable disassembling and thoroughly cleaning the inner works of your Uberti, the problem may disappear.  If not, a gunsmith who understands this particular gun can do this for you.  Your sign in doesn’t tell where you are located, but if I had a problem I couldn’t get solve locally I would contact Taylor’s Co in Winchester, VA.  They import a large number of Uberti products and have both in house gunsmiths and a good selection of parts in stock. I would suggest you contact them.

Back to the plethora of variations, my flat spring SST remains at full cock when the lever is worked.  My conversion of a Winder with SST added and my take down high wall with Ben Rice DSTs seem to vary in their half cock vs full cock positions depending on their “mood” that day.  . I’ve just developed the habit of checking the hammer position with my thumb as I get into shooting position.   

Froggie

I purchased a used one with double set triggers.  Set triggers seem to work when on the bench but the rifle never sets off the primer.  I can adjust it to the point that the set trigger doesn't work but it will fire by using the front trigger.  I know this isn't the way it is supposed to work.

I keep dickin with is from time to time and maybe one day I'll actually take it apart and see what the PO did.