The BT-4 is a very good gun. It is basically the same as a 98c, but it has a few nice extra features:
1) Slide-away feedport
2) The balance is better than the 98c, the 98c seems front heavy, while the BT-4 seems just right.
3) The picatinny rails are nice
4) The field strip is easier than the 98c, the trigger/handle comes off in one piece like in the A-5.
There are at least two production runs of this gun. The older production run has a ball-bearing detent, while the newer one has a reversible rubber detent. I got the older one. It looks like BT will support both types. Their customer support seems to be outstanding. The hex wrenches that came with my gun didn't really fit. Oddly enough they fit my friends Spyder MR-1 great.
Also it came missing one of the less essential O-rings. I called BT and they put one in the mail for me right away!
UPDATE: Got the O-ring in the mail today. They gave me a whole new set. What great customer support!!!
It has worked fantastic. When buying a gun I was choosing between a 98c and this one. If you are going for something that is tried and true and stood the test of time, then probably go with the 98. If you want something that is different, and seems like a slightly improved design, I'd go with the BT-4. I'll give it a 9 for now (wrenches/O-ring), and re-review it after more play.
UPDATE: After the good experience with customer support, I've up-ed the score to a 10.
10 out of 10
Last edited on Monday, April 2nd, 2007 at 7:47 pm PST