I didn't know the gun was loaded.

[Stophel]

A few years ago, someone brought me an Enfield rifle that his son brought from Afghanistan.  In the barrel (which had virtually zero rifling left, though the lock was pristine!) was a ROUGH cylindrical lead slug with blunt ends about an inch long that appeared to have been cast in an equally rough mould (stone? metal? wood?) where the two halves were not perfectly indexed.  Behind that was some bits of paper, and very little of anything that might have been powder.

[blunderbuss]

I've found some loaded one was a converted Springfield  percussion cut down to half stock and the barrel shortened it was wadded with newspaper, it just happened to have the date 1936 on the newspaper. Two I unloaded were used at the battle of San Jacinto,in 1836 powder was good in all of them.

[Steve Collward]

  I've dealt with three antique guns that were still loaded over the past several years.  As some have suggested, using water or oil to help soften or lubricate is very helpful. 
  While attending a muzzle loading event years ago, a friend purchased a Queen Anne reproduction pistol that he found on a trade blanket. Prior to making the purchase, the owner told my friend that he had dry loaded it and had not removed the ball. After getting back to our camp, we used a worm to remove the ball.  Behind the ball was a charge of powder. 
  This certainly supports the adage of "treating every gun as if it were loaded" and leaving nothing to chance.
sc

[McLeanWelsh]

Just recently got an old fowler that I suspect is a Cut down lorenz musket. The ramrob sad a little higher than i thought it should and i could blow no air through.

So I put an air compressor on the nipple hole and fired some air down it. The patch and powder came flying out the end. No shot or ball though.

This was my first one!

McLean