Follow Up Barrel Shaft Collar Trial Eley Tenex and Lapua Center X

Recent results of a barrel shaft collar revealed interesting findings at 7.5" from crown placement. That video precedes this one. The collars are stainless steel, appear semi-polished and are two part screw clamp type which do not scratch or mar the barrel.
Today I wanted to further explore the use of the collars. With nearly identical weather conditions as prior and same lot of Eley Tenex today was that day. The rifle is RimX chambered with 24" bull barrel and Trigger Tech trigger and a very solid WOOX stock. The chamber was 'cut' for Lapua ammunition which has a rim thickness of approximately 0.043".
Eley has a rim thickness of approximately 0.038". There is a difference. I had enough of the same lot Tenex on hand for this trial.
For the Eley portion of the test, 15 rounds were fired prior to target POA for fouling and to 'ready' the barrel. On this day the first two groups with collar (0.30" and 0.21") were very good, then distribution increased (0.50") for the third group for unknown reasons (?). The 5 accuracy rounds did not seem to me to differ much between collar and no-collar shots.
I would like to do a more in-depth shoot perhaps in the summertime with warmer weather and more time. Temperature and precipitation swings are quick this time of the year. The 'Weather Channel' gives me accurate forecasts for my 'window' of opportunity.
As the chamber was cut for Lapua dimensions I finished with a few shots of Center-X.
I shot 15 rounds of Lapua (following the Eley target) to line the barrel with Lapua lubrication and for sighting in. As can be seen on the Lapua target, it was not until after the 2nd group that things tightened up. That tells me it takes 25 rounds (15 fouling rounds plus (5+5 for two groups) 10 additional ) for a total of 25 rounds to realize the actual potential of Lapua (in this case), following a different brand (Eley). I'll have to remember that for next time. So, looking at groups 3,4 and 5 (.29", .32" and .28"), that signals to me that groups in the '2's will be a frequent occurrence once 750-1200 rounds have gone through the barrel to lay an accuracy foundation of lubrication and lead fouling. And I need to limit the ammunition to one manufacturer for consistency.
In regard to the use of the shaft collars with Eley. It seems the evidence is in favor of supporting a positive result. More work would be needed to further evaluate the protocol and requirements for success. For me, its just fun and interesting.
The Desert Precision Gun Works build seems to be nearly perfect without : )!