You're right.. you do have a problem. Take your rifle and put it muzzle end down on some soft cloth in a corner for a couple hours or over night. Let that oil leak back out down the barrel. This will coat the barrel and make it more slippery and also get it away from your drenched powder charge...

Then take the rifle to the range and pull the nipple. If you have Goex Black Powder 3f use that.Goex ignites easier them most powders.Take the nipple or bolster screw (if it has one and it will come out) out of the rifle. With a nipple pick keep packing powder into the nipple and bolster clean out scew as much as you can get in there. The trouble is the oil you poured in there will continue to kill charges.

When you feel you have as much powder as possible packed in there, put the screw back in if you got it out in the first place. Or the nipple back on. and be sure and push that maxi back down onto the charge or you could have a barrel obstruction there. Then fire that out if possible. Aim at something like a cardboard box that you can see if the maxi comes out and makes a hole. Sometimes it will only POP and you are not sure it came out. Other times it will fly 25 yards hit something and bounce back at you... Be careful a little powder can put a good pop on the projectile and it might ignite the original load still......

If the powder did not work, then get a quality bullet puller and a ramrod with a T handle.After your sure you have the bullet puller firmly into the maxi ball, hook the T handle in something like rafters, or a work bench and make sure the first pull on the rifle as you back away is strong and fast, this will normally get the maxi moving. Again, if the puller comes out, then put it back in and keep at it.

If all else fails, mail the barrel back to the company that made it or take it to a good gun smith, but you need to get that out of there and that rifle cleaned. Try the CO2 thing again... sometimes with the oil it will cause a plug to form and it will pop them out the second time. I have shot them out with a simple air compressor. Turn it up good and high and aim that in a safe direction and hit it with a good blast of air.......

When you get it out, clean the devil out of that gun and make sure the old powder is removed and you are clean.