That being said I'm really interested in the Duplex loads that were common in the early 20th century. I've done a lot of reading on them and have found out enough information to stay "safe" while loading duplex. The streangth of the browning 1886 won't be a problem. My question is do any of you have any actual experience with lading duplex ? Since this is a 9 shot repeater I'd like to be able to go through 9 rounds without the chamber or barrel getting too fouled up. If anyone has any older loading manuals with information on loading duplex would you mind posting some pictures ?

i realize that not everyone might like to share a load over an open forum. I'm just looking for an open discussion on the merits and drawbacks of duplex loads.

Given enough movement, wouldn't the powder shift around?  Now, if something was stuffed atop of the powder to keep it from moving, that would be different.  Duplex was used by Walter Cline in a .53 or .54 caliber muzzle loader to hit a 600 yards man sized target 4 out of ten times. I think you'll get slighter higher pressure and maybe a little more muzzle velocity.

Update: I loaded up some black powder carbine loads, 405gn bullet over 55gn of goex ffg.
10 were loaded with a light crimp , 10 with a heavy crimp. The light crimped rounds seemed to foul less. After 10 of either it needed a good cleaning.

I also loaded up 10 duplex cartridges. 405gn bullet over 5gn imr 4198 and 50 grains of goex ffg. Accuracy was quite good and fouling was greatly reduced alowing smooth clambering through all 10 rounds. I'll use the strait black rounds for fun but I've decided the duplex would be a better hunting load for Alaskan grizzly this September. Time to start tweaking my loads!

I'm completely convinced that black powder is the most fun shooting experience I've ever had along with machine guns and shooting supressed.
I'm already looking at getting another rifle to shoot black in. Maybe one of the new Winchester 1873's in 44-40!

I agree.

Some things to look into if you aren't using them already:

For maximum accuracy use a blowtube or swab the bore after each shot and also make sure you are using a Black Powder specific bullet lube.  This helps keep the fouling soft or gone in the case of the swab.

Are you compressing your powder?  A compressed load works much better.  Just don't compress using your bullet as a proper BP bullet should be soft and you will deform it.

I made my own lube out of 1lb of beeswax and 2.5 cups of olive oil. It worked really well and the powder residue easily wiped out of the bore. I'm not compressing too much right now. I'm using a drop tube to get the 55gr of powder in and a .30 felt wad over the powder. Gives me about 1/16 of compression. I ordered a compression die and plan on experimenting with heavier compression. For now the results seemed pretty good. I'm going next week with 50 rounds of ammo to sight my rifle in a little better ( was only shooting 50 yards last time unsupported)

Sounds like you're doing it right.  I use the same lube (equal volumes of beeswax and peanut oil) and a blow tube to shoot my .50-70 25-50 rounds at a time with very good accuracy.