I am surprised that the LYman Gunn/Snover bullet does not shoot well in your Brg BPCR 40-65(1:16 twist). Worked well in several of mine and also heard good results from others in up to mid-range distance. But it does "fall apart" at long range. 
Then:
My 1.325" long Elliptical minigroove bullet, cast from 9+1 shoots sub minute in 40-65 16 twist. Stable and Performs in 16 twist all the way out to 1K. Designed to do so: tapered/seated out and can get up to 75 gr Swiss 1.5 under it for up to 1400fps.
beltfed/arnie

Mick B wrote on Feb 15^th, 2016 at 7:58pm:


For a number of years now, my son and I have been shooting the Browning BPCR in 40-65.  We shoot Buffalo Arm’s 409 420 Grain "Money" Bullet Mould, Tapered 1st Band in both rifles and a 3rd rifle in 40-50SBN,  (link to bullet at BACO (You need to Login or Register to view media files and links)) . 

The bullet performs very well when the OAL of the round is adjusted so the nose of the bullet is slightly touches the rifling lands.  All of these rifles have Badger 1 in 16, 40 caliber barrels.  We load the rounds using Swiss Black Powder.  One rifle likes 1 ½ f, while the other two rifles like 2f.  We drop tube or vibrate the rounds to settle the powder, and then place a LDPE wad between the bullet base and powder.  Powder is compressed (using a compression plug die) just a tad (0.050”).  There is no neck tension; the bullets are slip fitted into the mouth of the case.  Lead is 20 to 1 and lubed using a 0.410 sizing die.  Shot to shot speed variation is less than 10ft per second.  At 300 yards, 1.5 moa is routine.  Hope this helps.

The Snover shot well in my Browning with 2F Swiss but I ended up with a NASA II monogroove bullet from Old West (Bernie Rowles). Perhaps oddly, perhaps not, but my rifle likes a little gap between the bullet and the rifling. Also I'm only using 54 grains of powder. More powder added very little velocity and just increased fouling and group size. Finding the sweet spot for resting the barrel is critical also. Mine is about 5 inches back from the muzzle. I tested at 1/2 inch intervals and marked the best with a piece of tape. One inch off that can make a big difference. I use Federal LP Match primers. My lead was 20 to 1 for the Snover (in extensive testing 25 to 1 was much more accurate than 30 to 1 and 20 to 1 was more accurate than 25 to 1). For the long nosed NASA II I had to go to 16 to 1 to prevent nose slump which would make itself evident at longer ranges.

I have shot the Lyman Snoover and the Saeco 740 in my rifle. Both designs were tried from 3 different casting sources and none of them were very good. 
However I have a large batch of bullets cast in a NEI mold #226 for the .405 Win. 
This mold is supposed to cast .412 but actually casts .410. Weight is 325 grains lubed and gas checked. I do not size them so they are only lubed and shot in the as cast diameter.
These bullets are not legal for silhouettes but they are about as accurate as jacketed bullets in my rifle using about 23 grains of SR4759. 


Mick B wrote on Feb 15^th, 2016 at 7:58pm:

Some of those early Browning 40/65 rifles had barrels that were chambered with a reamer with an undersized pilot and the chamber is not concentric with the bore. Do a chamber cast to see if this is one of those. If so you will not get great accuracy from it with fixed ammo.

Deadeye Bly wrote on Jan 18^th, 2017 at 8:24am:

Dave Crossno rechambered many of these to 40-82 with his reamer to clean up the bad chamber. However I have seen one of these shoot very well with a heavy RCBS bullet.

Thanks for the reply ssshooter. I doubt if the Brng. has any special throat. I believe a tapered bullet would be needed,not sure.And don't know if a seater is made for Brng. 1885s.