Re: chronograph Why?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body"> If you don't than you are not out in the cold because you still can get a pretty accurate velocity using drop figures at two distances. </div></div>
That is making the assumption that the scope is tracking properly. If it isn't then you are not getting proper velocity. Used properly a chrono will give you the velocity. I use mine to make ballistic data for matches and using JBM have never been off more than about .2 mils at 1000 and usually inside that.
A chrono is another tool which helps you get your velocity, ES, and SD numbers. It helps to give you an idea of what your load is doing. Like 427 mentioned you can make accurate short range ammo without it but if that ammo has 80fps spread then when you shoot it at distance you will see the difference.
Chronos aren't that expensive. Get a good one and you can use it for years. </div></div>
Not a bad assumption to make. If your scope doesn't track, you're f'd from the get-go anyway.
In response to the post about group sizes between two loads being the same, but SD being better for one: Who cares what the LCD readout says, if the groups are the same size? If you're limited to testing at 100 yards, I concede that group size isn't going to tell the whole story, and that SD # might help you some. But.... If you can test at longer ranges, I contend that what matters is group size, not some SD number.
I've been battling with my Chrono all year...
1. There is no accuracy/precision data claimed by the manufacturer (CED). I emailed about this and they responded that none of the chrony manufacturers make any accuracy claims, but was assured that it was "very accurate". What does that mean?
2. Lighting conditions have a major effect on whether the chrony will work at all, and what its readings will be.
3. Its a serious PITA to get to the range for testing, get the chrony set up, only to find out its unhappy today and isn't going to read.
4. Depending on the day, my chrony swears my current pet load (308, 45.5 Varget, 175smk, Lapua brass, Fed210M) runs between 2657 average, and 2685 average for 5 shot strings. SD is usually about 5-10. Based on my actual trajectory from 100 yards to 600 yards however, my velocity is actually about 2730. If I blindy plugged in 2657, or 2685 (chrony claim) into any ballistics calculator, I would be missing at range. Meanwhile, I have learned to always bring my .22 out when I chrony, so I can be sure its reading before wasting any money on good ammo through it. The chrony always spits out "reasonable" numbers for the 22 based on what the ammo manufacturer claims for that ammo. For example, the CCI minimag ammo that claims 1235 usually reads between 1215 and 1240 through mine.
5. I've lined up as many as 4 different chronys in series, with no more than 10ft from the entrance of the first to the exit of the last. I used my CED, a Pact, a Pro-chrono, and a shooters chrony. Extreme spread between chronys for any given shot tended to be 50-75fps. Thats a pretty significant difference, if you intend to use that velocity to base 500+ yard trajectories off of.
As far as I'm concerned, the chrony is only useful to have a good idea if your IDPA/IPSC/pistol competition load is going to make "major" (or whatever they call it)... Or to compare two loads relative to eachother, as long as they are tested back to back within a couple minutes of eachother, before the clouds in the sky change the lighting. I would feed fairly confident to say "yes, this one is faster than that one" with this type of testing....but thats about it.
