I have a 44-77 I have played around with a little bit and from what I have seen, it seems to shoot just fine right from the get go. I have plans to add 2 more BN cases to the heard. a 40-50 bn and a 44-60 SBN. I have watched a friend shoot his 40-50  and see nothing at all wrong with its accuracy. 
From my point of view the only issue or problem I see with BN cases is  a lack of flexibility in load volume. In Straight cases you can lower the powder charge with no problems, just seat deeper to an extent. BN cases are not quite that flexible. Its pretty much full charge or nothing.  Good fouling control is important, but its easily managed in a match  and in a hunting situation you are probably good for 3 shots. By that time it should either be dead or gone. 
One drawback that does really irritate me a lot is what they charge for dies.  The process for making a 3 die set is pretty much the same no matter what the caliber. You buy the reamers and make the dies. Yea I can see a little extra for odd calibers but a 3 die set for 40-65 is $185 and a 3 die set for and a 40-50 bn die set is $265. Step up to the 44-60 and you are up to $305. These are all prices from Buffalo Arms and all CH dies. 
In the past there was a wide variety of BN cases. They had to work to an extent back then. No real reason they will not work today, with in reason.  It just may take a little more work to get they to where you want them to be. 
Sam
 

Amen to that..!
I hope I out live the projects I thought about doing at one point or another..

I have a good friend that is a collector of old rifles and shotguns. 
His collection would make most firearm museum curators jealous.

Every once in a while he will send me a rifle & ask me to work up a load that shoots.

After doing some research, have a mould made and work up a load I send it all back with my notes and the best targets. 

Lately though the risk of shipping a rifle has become so dicey, I am loath to do it anymore. Last Place I want to be is inside the circle of blame for a missing heirloom.

Bob 
bullshop wrote on Aug 16^th, 2026 at 1:32pm:

I'm the opposite. 
The rifles I shoot the most are those that are the most accurate, and make me look like a better shooter. Nothing is more fun for me that to get a gun and cartridge that consistently shoots small groups at whatever distance I shoot with it. Those guns almost always go to the range with me, even when I'm testing and working up loads for other new rifles.