If you have a .177 XS-B4-2A then you're looking at around a nominal velocity of around 750fps with what you find in the QF-2 kits(spring/seals), If you're shooting a .22 XS-B4-2A, then you're looking at a nominal velocity of 650fps w/ a QF-2 spring change. If you need more power than that, then you're going to do a little more work than just changing the spring, and use something a little better than what you'll find in the QF-2 kit. I have a .177 XS-B4-2A that's currently shooting Beeman Laser's at just over 900fps, mind you that's with a Quest 1000 spring and completely over-hauled internally(honing/polishing/deburring, and finally lubing)You also have to remove the bear-trap to increase your swept air volume, Anyway's I hope this help's, Cheer's, Andy
Posted on May 14, 2008, 4:21 PM from IP address 64.228.90.216