Jump starting Blackhorn 209

I know that Blackhorn 209 powder is not reliable in a traditional sidehamer #11 nipple gun. If a person was to use a fizzen size amount of 4F blackpowder(very small amount) and then used a regular charge of Blackhorn 209. Would there be any undue pressure to your gun?

I don't know for sure, but I suspect so. I know that BH produces more blowback in my inlines than any other powder.

txhunter58

venor, ergo sum (I hunt, therefore I am)

If you are going to try a "duplex load" that uses Blackhorn209 powder, you don't need 4Fg black powder which is for pan priming flintlocks. Any regular black powder for your rifle like FFg or FFFg will work. Pyrodex or Triple 7 will work as long as it will normally ignite using a #11 percussion cap or musket cap.
However, Why?
As Txhunter has pointed out you could get excessive back pressure, enough to blow the hammer back to the half or full cocked position. Also if you have used another substitute powder in the bore to help ignition you now have that fouling in your bore and you will need to clean just like you would using black powder for the entire load.