Update: Range report
I want to thank all of you who chipped in on this thread. Remington Thunderbolts were all that you said they were, and then some. All I can say is...wow. These bullets are in a class all their own.
The Good:
We shot 800 rounds of the stuff through the gun, with no failure to extract, or failure to fire of any sort. We did have three failure to feed, but consider that not too bad, having had worse troubles with CCI ammo in that respect.
The Bad:
These bullets fire dirty. Obscenely dirty. After 25 rounds of the Thunderbolts, the rifle was far dirtier than it was after having 1000 rounds of other ammo pounded through it without having the action disassembled and thoroughly cleaned.
The outside of the casings, as some mentioned, had all sorts of powder residue on them after firing, even down to the rim. I was firing in the jackknife position, and so much crap was spewing out of the breach, it was burning my arm.
We also found a couple of casings that were split. Never seen that before in .22 lr. As a guess, I am thinking there was some pressure increase due to the fouled barrel (see next paragraph) which caused this. I kept the casings; if anyone wants to see a picture, I can put one up.
In the end, a fouled barrel prevented us from continuing. The muzzle report was getting quieter (as in
this post), and any accuracy went out the window. We could not even hit a Redstar target at 60 yards anymore, so it was time to pack up and go home. After a good barrel cleaning, we will continue putting the Thunderbolts through the gun until the action stops functioning properly.