That is why before I pull the trigger so to speak on a project I tend to ask a bunch of questions as I know there are a lot of people out there who know better than I do.

You are certainly right in it be a load of extra powder and lead going up in smoke. Thats why not fully happy with the 32-40 the miller and dell were born.

Also a twist of around 1:30 would be optimal too faster twist especially with lead can hurt accuracy. 

My initial motivation for large cases is too achieve the same velocity with lower pressure.

GT wrote on Aug 23^rd, 2017 at 11:28am:


I have to whole heartedly agree with GT!

I also had a burning desire to build a 50/90-100. I've forgotten the exact case I wanted but, it was based on the 348 Winchester case. 
I had bought molds for it, over the years that I coveted it, the last one a NEI 600 gr GC mold (I was going to ream the GC off). Before I bought the barrel, I had got a 500 gr 45 cal bullet for my 45/70 (had been shooting a 409-430 gr) and took it to a BP, BR, 200 yard match. In that match, I shot 65 rounds, BSed with 70 gr FG and 15 gr of 296 as a duplex load. All the ase would hold.


I had been shooting my 45/70 for 9 years at that point but, that load was responcible for tearing my should up, so I couldn't shoot for approx. the next 12 years. A heavy price to pay!!! I had said to myself that the recoil wouldn't hurt me and that it was just what I had to endure to shoot those 45/70's that I HAD to have.

So, I sold off my 50 cal molds and gave up my plans to build a 50.

Frank

I can't imagine why anyone would want to put smokeless in a BP cartridge. Not sure the fixation on velocity either. Fill the case as full of powder as you can and still seat and chamber the bullet. The velocity is what it is. And recoil is not a factor whatsoever if you buy a leather slip on recoil pad for $38. Looks good feels good no problem. 
I have a 50-90 that I am working up loads for with 98 grains of Swiss and a 600 grain bullet. So far it is more accurate than with a 550 grain bullet. I killed a buffalo with this rifle and I am glad to have done it with a BP load in this Shiloh Sharps 50-90. It weighs 13 pounds and that's enough. You don't need to build a rifle that you can't lift.  My 45-70 carbine will kick the snot out me with 69 grains of powder and no recoil pad but the 50-90 with 98 grains and the recoil pad is much more pleasant to shoot. Go to the Shiloh forum and ask some questions there - look at their website for building a rifle. I went to auction sites and looked at actual buffalo rifles from past auctions and made my own "picture book". This gave me some ideas on what was historically accurate in the old rifles. For instance - a lot of the old Sharps buffalo rifles were 30" barrels because anything longer cost more money. The pictures are free.  I love my 50-90. Good luck.

Can't answer your original question about breechseating and the 50-70 vs the 50-90, but will give you some anecdotal information about my experience with 50's.  

I had a 50-70 with 36 twist, it would only shoot the 450 grain gov't bullet.  Anything longer wouldn't stabilize.  Bought a 50 alaskan rolling block, had a lot of different molds with it, mostly for smokeless, and the fellow before me had loaded it to absurd levels, wonder it didn't blow up.  It had a brass crescent buttplate!!!!!! and was brutal to shoot, light weight, poor stock design and the buttplate.  I passed it on and kept most of the molds.  I built a 50-110 with a 36" 1 1/4" 20 twist round barrel, and it was a very mild shooter and I only used 750 grain bullets in it and a full case of black, as I recall about 107 or 108 grains of 2f express goex for about 1275 fps.  It was quite accurate, out to 1000 yards.   I built a light weight 50 Alaskan on a rolling block after that, using another 20 or 22 twist barrel in a sporter taper.  It is quite accurate, using 550 to 750 grain bullets and about 90 grains of black.  Good hunting rifle. 
I built another 50-110 with a 1 1/4" x 20 twist tapered octagon barrel, 32" long.  It is accurate with the 750 grain bullet and recoil is quite manageable.   

The mystique of the 50's is just that.  It's just another cartridge, works the same, has the same ballistics and same characteristics of any big bore blackpowder caliber.  The ballistics of the 750 grain 50 are about the same as the ballistics of a 525 grain 45 bullet.  The recoil is about 1.5 times that of my .45-90.  

As far as motivation to own one?  For me, it's about interesting cartridges and building them.  Same reason I have a .270 REN, 22 K Hornet, .338-06, 375-06, 429 express, 25-20, .32-20, .375-405, 458 mag, 458 Lott, 40-70 SS, .38-72, .450 Nitro Express, .222 Remington and a few others.  I enjoy building something other than the standard .270, or 308 or .223 or 7mm mag or .45-70 and enjoy shooting them, regardless of how big or how small they are.

On my to do list are a few other unusuals that I want to complete:  a .375-21/4" nitro express english style rifle, a .500 ultra mag, a 6.5-06, a 6mm-.223.

I'd go for the .50 if you want it, and use the larger case and black powder.  I found the .50-70 to be pretty limited on the two I experimented with.  Larger case and heavier bullet at 1200 to 1300 fps were the best successes I had with 50's.

   

OLR,
Thanks for that, I purchased a couple of the velcro pads mentioned earlier in this post a few years ago, the velcro does take away some from the classic look, ordering the buckle style now.   
G

I bought a couple of lace-up all leather recoil pads from some guy in the Ukraine for $9 on EBay. What the heck $9? They work great and would do for hunting because they won't get loose and possibly slip off like the velcro pad. I like the velcro pad for the range because it takes no time at all to change the pad to another rifle. Just put 27 rounds through my 50-90 today checking sight settings out to 500 yards - no problems. My little 10 pound rolling block Creedmoor kicks almost as hard in 44-77.
OBTW I breech seat a paper patch bullet in the Creedmoor just like they did at the Creedmoor matches. It's chambered to do exactly that.