Random comments as I read through the great info you posted:
- Wow the velocities on the Gold Dot 115gr were very consistant. I like the extra 50fps on the 115gr. Did you notice any difference in felt recoil between the 115gr and 124gr, or did they feel pretty much the same?
- I was surprised at the spread on the Federal 9BP. I didn't expect it to be as tight as the Gold Dots, but didn't expect it to vary quite as much as it did.
- The expansion data was very interesting (and yes, I know, it's a small test with a small sample and people aren't made of wet newspaper). I do think it is useful information to compare how these rounds do at the reduced velocities from the shorter R9 barrels. It seems Gold Dots are once again showing how well they expand at lower velocities.
As for the primer marks, I know SIGs often show that sort of mark. Supposedly they are engineered to keep the firing pin slightly protruded during the extraction phase to keep debris out of the firing pin channel, so you can get drag marks like that on the primers. I've often wondered if the rearward movement of the slide just causes the firing pin to protrude slightly due to momentum and cause that. Perhaps that's what happens on the R9.
Thanks very much for this great information! This will be very useful to many people. One suggestion - you might want to add one more page that just has one big chart of all the chrono data, with one row for each type of ammo. Then as you test more (or others provide chrono data) you can have a one-stop page for comparisons.
Oh - and sticky this post up so everyone can find the link to your data quickly.