Take a look at one of these.Small, light, accurate and Infra Red so the don’t need any external light source. They attach to the barrel (yes, they will fit in a Talon/Condor frame or shroud) so it is impossible to shoot your chrony!!! http://www.chronoscopes.com/
I’ve used one on several rifles including a modded SS and compared the results with my Shooting Chrony. Never more than 2 fps difference.
One thing, though. They do NOT give standard deviations of record the individual shots in a string. They DO give averages and can be set to give FPE or FPS (energy or speed) for each shot and averages.
Overall, a nice small unit that is easily transportable (it fits in your pocket) at a very reasonable price. Mine cost about $80.00 shipped with the alignment tool (GET the alignment tool!). Well worth a look, at least.
I searched for a long time and this is the best deal I could find
http://www.midsouthshooterssupply.com/item.asp?sku=00084MASTERGAMMA