Thanks for posting the video, HD.
In pistol cartridges with small powder spaces, the test is complicated because primers will sometimes start unseating the bullet before the powder burn gets underway, thus increasing the burning space and lowering pressure. The 1½ in Jim's test may have failed to do that where the others did not, thus raising peak pressure a little. I wondered if the first pressure reading in the video might be explained by a failure to unseat the bullet as the others did, but it might also have been a clean barrel with no graphite from the powder coating to help lube the bullet on its way into the throat.
I was looking at testing current production CCI primers last fall but couldn't get to any before the store shelves emptied. The specific issue I am interested in is CCI #550 vs. the #400. CCI told me some years ago that they were the same primer in different packaging, but a more recent call got me the statement that interchanging them was "playing with dynamite." In the first instance, the lady on the phone actually looked up the cup and anvil part numbers, the priming mix, and its quantity while I was on the line with her to confirm they matched. She also told me their own employees buy the less expensive #400 for both purposes.
In the second, more recent instance, though the primers could have changed since my original inquiry, no such care to check the assembly was taken. The "dynamite" statement had something of the ring of a company liability policy to it. That is why I wanted to run a test myself using 38 Special cases with flash holes opened to ⅛" and some wax bullets to shoot over a chronograph to assess the primer mix strength without powder. I also wanted to weigh the fired cups and anvils on my analytical balance to see if they were significantly different. My reasoning is that if bullet unseating is involved in pressure readings, it might happen with slower powders and not with really fast ones, which could change the outcome using loaded rounds.
The video clearly shows no dynamite is involved. The samples are too small to say absolutely no difference exists, but if it does, it is obviously fairly minor with the powder used, and maybe it will turn out to be so with all of them. It's nice to see a bit of confirmation favoring the old inquiry I made.
