slo pitch: That sure don't sound right.
I think you'll need to give a litle more info and answer some questions before you get a definite answer.
1. What kind of powder were you using and how much? Triple Se7en has a habit of leaving a "crud ring" behind in the area where the bullet is seated on the powder. It USUALLY can be removed with a damp patch so the next will seat on the charge again (a 50/50 mixture of Isopropyl Alcohol and blue windshield washer fluid is what I use.)
2. What is your bullet? Are you using a sabot? Sometimes sabots leave plastic behind - especially with heavy (hot) charges. That is more difficult to clean out than powder residue.
3. Can you visually inspect the area and see that the bore is completely clean after you swab it?
The fact that the first bullet goes all the way down and the next ones don't makes me think it has to be a fouling problem. Many CVA guns have very tight bores, and you may have to experiment with some different sabots to find one that loads better. Harvester Chrush Ribs are thinner than most, and MMP makes a few different thicknesses - I believe the higher numbers are thinner than the lower numbers (HPH-12, HPH-24, etc).
BUT - if you can't get the bullet all the way down on the charge, DO NOT shoot it with a space between powder and bullet!! That is VERY dangerous. You should have a "witness mark" on your ram rod at the muzzle with a bullet seated properly on the charge. If you cannot get the next one to that mark - don't shoot!
Maybe others will have suggestions, but I think they'll want the info I asked for in my questions.

Good Luck