Purchased a lymans BP trade rife. Took it out today to shoot. Gave the ole blow down the barrel to make sure no obstructions. Loaded it up and slammed a sabot down the pipe. Percussion cap went on and squeezed the trigger. Just the clap of the cap went off. Loaded another onto it and another clap. Tried 3 more and still no bang. Took my nipple cleaner and tried to probe. Now I gotta take the nipple off and see. However if all looks good and it won’t fire what’s the way to vet a polymer tipped bullet out? Can I unthread the back and push the load through? Never tire one apart before. I used FFG powder and I’m sure it’s down by the hole.
Don't try to remove the breech plug. They are usually so tight that you'll end up scaring up the barrel and the plug if you do.
Under the nipple, there is a small hole that connects the nipple to the bore. I call it a "flame channel". If the gun is new, that hole probably is plugged up with grease. Buy a package of pipe stem cleaners. The ones with tiny wires in them to make them abrasive are best but regular pipe cleaners will work. (These are sometimes available at drug stores, tobacco shops and hobby shops.)
Remove the nipple and run a pipe stem cleaner down into the flame channel as far as it will go. Rotate it as you push it in. Then, pull it out and run another one in. Repeat this until it comes out fairly clean.
Then, pour a little powder into the hole where the nipple goes and work as much of it as you can down into the flame channel. When you can't get any more in there, remove enough powder from the nipple hole to allow the nipple to screw back in.
Cap the nipple and try shooting the gun. 90% of the time it will fire on the first attempt. If it doesn't, remove the nipple and reload the flame channel, put the nipple back in and try again. It might take several attempts but sooner or later, if you loaded a main powder charge, it will fire.