Been a lurker for the last 18 month ever since buying a .243 youth model for my son last summer. Sorta caught the addiction last fall and started to get interested in building from parts a 20 gauge Ultra Slug Hunter. Picked up an SB1 receiver from GBO classified's last fall locally FTF. Picked up the 20 Gauge Ultra Slug Hunter barrel from GBO classifieds this spring. It fit my SB1 frame pretty good, but had to close it hard. Had a full size pallet stock set that I purchased from the factory for my son's .243 youth model to permit the gun to grow with him (that was before I found GBO classifieds). Recently purchased new a Bushnell Banner 3-9X40 with 6" eye relief and got it mounted last week. Last Saturday I headed to the range and got to shoot my newly built toy. After a few scope adjusting rounds at 50 yards, the gun shot really well. Only shot five total, but the last two were touching dead on POA at 50 yards using 2 3/4 Federal Barnes Expanders. The gun was a joy to shoot. The only issue was that it popped open on each shot. I thought that might happen given the force needed to engage the latch mechanism. Using the FAQ, I read up on pop open medicing. Made sure I removed all lubrication from the latch shelf and that improved the lockup a good amount but not enough to my liking. Working on removing material from the pivot point on the barrell in VERY VERY small increments, I was able to be a very solid latch on each and every engagement in only about 30 minutes of work. Can't wait to put some more rounds through this gun to see if that took care of my pop open problem. Only issue I've run into so far is that I purchased a full size synthetic stock from the GBO classifieds to utilize for this setup and return the pallet stock to the cabinet for my son later, but the forend barrel channel is too narrow for the Ultra Slug Hunter barrel. The synthetic forend matched up to my son's .243 just fine, so I'll just put away the synthetic full sized stock for him to utilize at a later date. I probably could have modified the synthetic forend to work with a little effort, but figured it wasn't worth the effort at this point. On my next range trip, I'll take some pictures of the gun and results. Should be just the ticket for the next shotgun only lottery hunt that I'm drawn for! I wanted to say thanks to all those folks who take the time to post up their issues and solutions. The internet is a very powerful tool!