RE: Mustang/Blackhorn Issue Not Looking Good
 

Semisane - I think the problem is twofold. One is the 209 vs the small pistol primer. Second it the distance and volume of space. That small pistol primer pressure has to fill up the entire 25 ACP case before it travels down the flash hole.
With the Omega you have a smaller diameter flash hole and a more primer flash with the larger 209 primer. Hence a longer flame with less space to fill.
I am not an in-line expert but that would be my guess.
I can't really say what the problem is with the 209 breech in the Mustang.

RE: Mustang/Blackhorn Issue Not Looking Good
 

Semi

I've modified 4 of the Domed Knight Revolution plugs, so they would work in my Disc Elites with BH209. They work perfectly with NO hang fires even after 40-50 rounds at the range. They use a plastic jacket, but you have an even better 209 to plug seal!! So just drill it out about half way with the 1/8 drill and start testing it:)

It's like channeling water thru a squirt-gun or fire hose:D, the larger 1/8 flame channel hole gives a good colum of water to be forced thru the .035 flash hole/nozzle. Your flash hole/nozzle may not need to be changed at all

RE: Mustang/Blackhorn Issue Not Looking Good
 

What Lane says is true, and if it builds to much pressure because it can not go forward then it will go back as blowback which seriously limits what gets to the powder. The touch hole should limit pressure coming back from the barrel not what the primer needs to build to go into the barrel. Lee