I recently posted photos of a sporterized trapdoor that I recently acquired. I have done lots of 45-70 shooting with Sharps rifles and trapdoors, and never had a problem with recoil.  However, with this particular rifle,which has the original military buttplate, recoil is a real bugger even with relatively light loads (19gr 4759 with a 440 gr bullet).
The buttstock is a little bit long for me, and I am thinking that the long buttstock is affecting my hold on the rifle and causing the buttstock to not be placed where it should be all the time. If the lenght of the buttstock is the problem or a significant part of the problem, I will shorten it, but I dont want to do anything until I get an accurate diagnosis. 
How much, if any, does the buttstock affect the "felt" recoil? I realize it doesnt actually affect the recoil itself. Thanks, Joe S

Light Trapdoors with the Arsenal butt-stock configuration are kickers. I Used to have a H&R Officers reproduction and sold it mostly due to it's recoil in 40 shot gong matches, this with a 330 gr 45 bullet loaded sub sonic.  They were designed for hunting and infrequent shots, it's not a bad stock for quick snap shooting.

The Full Trapdoor rifle is very good for runs of 40 shots if they are used offhand and at short range, Our local Gong Matches fired offhand 200 yards have been won by Trapdoors many times. Prone is difficult, Bench all but impossible, even if you can handle the recoil it corkscrews off bags with  poor results on paper.  

Shoot the Arsenal configuration Trapdoor mid to long range 600 to 1000 yards off cross sticks your head is up in the air with no cheek support at all.  In there heyday Trapdoor Target Rifles produced by the Arsenal  for Creedmore stye matches used Hotchkiss butt-stock configurations. Picture of one in Waite and Ernst Book. Flatter plate straighter stock and higher comb

Best Stock for handling recoil prone is about like the Winchester Marksman, one they used on M 70 Targets.  Lay one over a successful BPCS rifle and the principal dim's are about the same.  How you plan to shoot the rifle is the most important thing.  Most bench guns are difficult to shoot offhand.  Ever see Service Rifle shooters use  AR's offhand ?   They put the buttstock high on the shoulder only the tip of the toe touches the shooter, of course they use a pipsqueak cartridge and lead weight the gun up to 14 or 15 # recoil is not an issue.

Boats