Of course no one is there to actually watch what you may be doing, but if the primers are good, the BH hasn't been compromised, there's no reason that rifle should not have went off the second time. UNLESS.... you have been using way to much lubricant after cleaning, OR... there is a possibility that something might be wrong with the breech plug. I would rather first believe its something being done wrong before it being a bad OEM breech plug. However, stranger things have happened.
If you have to push a bullet and propellant out, push it out the barrel unless its not possible at all. Even pushing it out the barrel it ends up being a mess, but it doesn't push all the propellant into the trigger assembly. If you have to push it out the breech, remove the trigger assembly first.
Use a Hoppe's coated patch and cleaning jag and push it out the muzzle.
Make sure the stock is no where near then........Get some non-chlorinated brakleen and spray the hell out of the trigger assembly, which should dissolve any BH in the trigger assembly. Now, once you spray brakleen in that trigger, it removes ALL the lubricants.
DO NOT lubricate your trigger with oil. Re-lubricate the trigger assembly with lighter fluid. Lighter fluid contains just enough lubricant to lightly coat the trigger assembly without gumming it up. VERIFY IT WORKS PROPERLY.
If you plan on shooting the rifle the next day or today even, after cleaning it and making sure that the barrel is completely dry, don't lubricate it. Its not going to rust up or pit just over night. When you install the breech plug, if you're using grease, do not get it on the face of the breech plug.
Re-assemble the rifle and VERIFY that the trigger is working properly FIRST. If everything is working properly, then as mentioned prior, fire 3 primers only. Listen for any difference in the sound of the primers. All 3 primers should sound the same.
Load it with your normal charge and bullet. Don't swab between rounds and if you have to, to get following bullets loaded, use just a dry patch. If they're loading too tight where you have to drive them down in a fouled barrel, the bullets are sized wrong.
If the rifle doesn't shoot the following rounds after that process, then there is likely some kind of issue with the OEM breech plug. At that point, my personal preference would be to contact Jeff Fisk at Bestill Creations. The other plug mentioned will also work.