Hatz Biplane Association

I'm building a CB-1, but in looking at some pictures of Classics it appears there is a slight change in the Spring Assembly on the Main Gear. On the CB-1 the lower "collar" is welded on and then the spring and upper collar can never be removed, even for painting under the spring. It appears on the Classic the lower collar is held on with (I presume a 5/16) a bolt instead of being welded on. This will require a slot I'd think in the 3/4" tube on the inside and it also appears this bolt acts as the "safety bolt" which is called out in the CB-1 plans.
The main difference looks like instead of slotting the outer tube for the safety bolt, you instead slot the inner tube for the bolt which doubles as a safety bolt and holds the lower collar in place.

Is there more going on here than I see in the pictures? Does slotting the smaller tube require it to be a heavier wall to allow for the slot which weakens it or is the inner tube still a 3/4 x .065? Also, regarding tube size, the outer tube calls for 7/8 x .065 and then boring it for a slip fit for the 3/4 inch inner tube. Instead of trying to bore that tube so deep, has anyone tried simply using a 7/8 x .058 for the outer tube and not boring it? What tube sizes does the Classic plans call for?

You are right that both tubes are slotted for the spring retainers. The inner tube is 3/4 x .090 and the outer tube is 7/8 x .058. Here's a scan from the eval. drawings. Most of the dimensions are redacted, but it will show you how it goes together.

Great Doug. Thank You - that's just what I needed!!