Timbolero,
Get yourself one of the flat steel 209 primer capper/decappers, they work wonders on stubborn primers. You can buy them for under $5, and worth every penny. It is a very good investment to have handy while hunting especially. I can go through a whole shooting session sometimes with no sticky primers, but other times, depending on the charges and bullet weights I will have some that stick occasionally. If you have the tool to remove them, it only takes an extra second. If you don't, you are done for the day. If you need a follow up shot in a hunting situation and you get a sticky primer, it will be money well spent. Not all primers are created equally, not even the same brand from one lot to another. Not everyone shoots the same primers, powders/charges, or bullets/weights, all factors of sticky primers.
Im with Nick as far a 777 primers go with the MU Plug, I have tested every primer I can get my hands on with BH209, and never had even the slightest delay. The short path to the powder allows a very large percent of the heat, flame, and pressure to reach the charge. I would not recommend them for a Knight, T/C, CVA, Traditions, or any other breech plug due to the long flame path they have to go through.
Like Nick has stated, the tollerances on these rifles must have a pretty wide window. You can get away with that when you use that leaky plastic primer carrier, as evidenced by the massive blowback, but when we want a precision fitted breech plug the differences in rifles is very noticable. There is only .003" difference in my examples, but there are others that have much larger deviations, maybe as much as .010" or more. Then add in ALL the primer variations, as much as .010" in just length alone, and you have a real headache to deal with. I really think that this is the reason nobody else besides Nick wanted to deal with it. Thanks Nick!
If Nick wouldn't have taken on this challenge, we wouldn't even be able to discuss shooting Blackhorn 209 out of the NEF Huntsman/Sidekick rifles without paying a gunsmith to custom make a breech plug for YOUR rifle. I would hazzard a guess that I have more Huntsman/Sidekick breech plugs (at least 18) than anyone I know of, and Nick's MU breech plug is the ONLY (non-custom) available plug that will ignite Blackhorn 209 reliably. The .25 ACP breeech plug will not do it reliably either, so save your $59.99 + Shipping. I have a custom Hubbard plug (needed .012" shim below the 209 primer pocket adapter), and another custom plug that will do it, but these were "one time deals".
Follow Nick's advice, and you will get it figured out. I have meet Nick in person, you won't find a better guy to deal with. All of my CUSTOM plugs had to be tweaked to fit the rifles just a little bit, it is just the "nature of the beast" when it comes to these H&R/NEF muzzleloaders. Once you get it right, you will love it. I will take my $200 Huntsman over any other muzzleloader in my safe, and it has some very good company. 3 White's, 7 Knight's, 3 H&R/NEF's, and 1 T/C.
