Re: Looking to get a new chrono...what's good?
I own/use 'em all and prefer the PVM-21 for it's simplicity and accuracy. (Disclaimer, I do not use the software, but use it in stand-alone mode).
The M2 requires some mods to be consistently accurate. First, you need the IR screens which will run another $90. Second, you need to make your own rail. The folding one supplied tends to over-extend (or lift if you face it the wrong way) such that your screens are not 2' apart - usually off by 1/16 to 1/8". I'll leave the math to calculate resulting error as an exercise for the reader. I recommend buying some 1"x1" AL stock and cut it to length such that your screens are exactly 2' apart. Drill and tap for tripod mounting. (PM me if you decide to go this route as I can save you a lot of time.) Thirdly, you will need a "coffin" to shield the M2 from direct sunlight. I make mine out of black foam board purchased from Staples. Three pieces duct-taped together does the trick and usually lasts for one heavy season. Fourthly, not a mod, but a tip, always keep your leads separated as they are not shielded and will produce errors if you run them too close together.
These changes make the M2 a decent chrono and I always like the large screens to shoot thru as it makes for a good chrono to set up at distance if you want to do some BC measurements.
I usually run the PVM and M2 in tandem and the PVM-21 always reads higher by 7-10 fps. Consistently so, though. I always recommend mounting on a sturdy platform such as a surveyor's tripod and keeping things downstream from the muzzle blast by about 15'-18'.
While the 35p's are known for producing accurate results, I get very similar results as my friend and his 35p and can set my two up faster then he can deploy his one. I also have some frustration with Oehler for not updating their technology over the past few decades. They certainly had the opportunity before their last "revival" of the 35p.
