I thought a few here might look at this: This first picture shows the 'barrel bed length'. It is measured from the vertical impact surface to the top of the feed ramp. You need to slightly angle your calipers to get beneath the top edge break of the VIS. This measurement needs to be .246" minimum. This one measures right at .246". This shows a new and un-fit Kart bbl fully nested in the frame. Notice the overhang. The next two show a Kart bbl faced back and re-throated to privide the proper gap. Pic of the unsupported case area. If needed it could be deepened even further.