I have the same gun and i emailed pedersoli with that very question.
The simple sight installed on new guns is not the precision adjusting vernier elevation type and has no controlled windage that this gun really needs. That simple sight is ordered by dealers so the buyer has at least some type of tang sight to get started.
Check our web site for the soule type of conventional vernier elevation tang sight types which will allow maximum accuracy from the gun.
Best bargain is the wood boxed set USA170 which gives the fully adjustable front sight plus a soule tang sight and Hadley eye cup ...etc.
The original Sharps was considered a strong action. Ballard and Stevens were considered weak. Now with modern replicas of modern steel plus we enlarged a few frame members etc. the gun is truly strong.
It is proof tested far higher than 29,000 psi chamber pressure using steel ctg cases. The brass cases are too thin walled to be safe past that pressure. The gun can take it though.
Our Sharps, High Wall, Rolling Block and Trapdoor are all of similar strength. The Win 1886 model is another antique design which due to steel of that day is not safe with pressures beyond 29000psi.
If we made a modern 1886 it would be much stronger.
Shooting a heavy 405 to 500 gr bullet at 29000psi will punish the shoulder and recoil is fierce.
Target shooters find best 1000 yard accuracy with loadings around 26000psi and using 550 gr bullets or similar.
Check out www.bpcr.net
where under technical info. you can scroll down to a good reloading article and lots of advice.
For DP & CO.