Difference
Howdy jagdpanzer. I ran a test on it about 2 years ago, and quoting from memory...but it's accurate, since I don't run many ammo tests unless there's a new kid on the block that I wanna check out.
Besides the ammo being dirty when fired, the brass is short/out-of-spec at an average of .885-.888 inch long after sizing, and the velocity has a lot of variation...running from a low of 770 to a high of 820+fps. Not conducive to the best accuracy. This was a test of 2 10-round groups in 2 different lots
for a total of 40 rounds chronographed. Q4170 generally varies less than 25 fps in a 10-round test lot, and the brass is consistently .893-.895 inch...which is good for consistent primer ignition.
The Valu-Pak ammo issn't bad for general use and fast action practice, where the targets are close and large, and does a pretty good number on falling plate machines with 8-inch plates at 10 and 15 yards...but it falls apart at 20 and 25. At least in my hands. Note that I'm not that sharp on 25-yard plates unless I really bear down. A better shooter may have better results.
If you're into target work at distance, and want to get a better idea of what your gun will do, go with the USA brand. If you're a close-range practioner of
fast defensive type shooting or IDPA/IPSC matches, the VP will do.