I probably stirred the pot by introducing a multitude of combinations.
Part of my "cross combatibilty theorem " is based on, IMHO, a lack of reloads for 75mm unless you want to invest in multiple brands of hardware. Yes, CTI has a lot of reloads but availability has been poor as of late.
I invested in all snap ring hardware when Paul of AMW and Frank of Kosdon were still with us. But now have CTI, AT, LOKI as the bigger manufacturers.
CTI designed their 75mm reloads nearly identical to AT. That is why they were easily certified in AT hardware. Now AT has followed suit with theirs.
CTIs "hubcap" or 75mm adapter system is a very well-designed system.
If the CTI and AT reloads are identical in dimensions and the CTI reloads are certified in snap ring hdw therefore the AT reload works in the snap ring case, as long as you use the seal disc, adjustable fwd and corresponding nozzle holder with both o-rings.
As long you have a well-engineered plan and an excellent building technique, the hardware will not fail. Once in a while you'll get a reload that fails. No hardware will stop that.
The only reason for the hub cap was so CTI loads could be used in "their" partner's AMW cases. (They work in Like and Kosdon cases, too, but are not certified)
Allowing more flyers to save money using their Snap ring cases, I'd say that was a great idea on CTI's part. The snap-ring reloads, for instance, that fit in the 75-7600n case do so with no hubcap. (I sometimes use an extra nozzle washer to fill the case entirely).
The reasons for the development of the "hubcap" :
1) Since the graphite nozzle takes up more space in the case than the CTI nozzle is why its needed.
That way you are not having to have custom spacers but then it is still not compressed.
2) The CTI reload is slightly compressed in the CTI case (just like with AT loads).
The hub cap serves that function to simulate that assembly.
The hub cap has made another safe option for flyers, saving money on hardware lets me buy more reloads.