OK< I went to range early this morning. Started shooting at 7. I took readings with chrony in shade first, then in partial sun, then in full sun, and finally, with the skyscreens canted toward the sun as if it were at high noon, just at an angle. I tried to keep the shots in the middle of the triangle between the sky screen and sensors.

I kept some pretty good records, but will enter them later if interested, since data is in the truck, and my computer isnot inthe truck. I used a 22LR with Remington thunderbolt ammo for general calibration, the 22lr ranged from about 1250 to 1380 fps.

With 22 LR, it seems the shade readings were a little bit on the high side. with red-tipped nosler ballistic tips, it seems the partial and direct sun readings were 200 fps high until the unit was canted toward the sun, with the skyscreens shading the sensors.

Now for the hard part: with 140 grain and 160 grain Nosler whitetipped Accubonds, the readings were teh same or even higher with the screens canted, but it was also getting towards 85 degrees in the sun. My shoting bench, rifle, and bullets were shaded, the rifle remained fairly cool, and yet the velocities were higher than expected without pressure signs. With my 26 inch barrel and Fed 215 primers, the machine read 3300-3400 fps for 63+ grains of Reloader 22 in a 280AI. A quickload run for me yesterday showed this load to be less than maximum pressure (although without magnum primers), and Quickload calculated velocities of 3050-3100 expected from a 24 inch barrel(actually Nosler partition 140 data substituted for accubond in quickload). So, could the Magnum 215 primers and the extra 2 inches of barrelm add 200-300 fps? I doubt it. Dont really want to hack off 2 inches and reload some CCI 200 primers and check it that way.

The best or worst news is the load was the best yet for accuracy, with two groups of 3 shots each measuring just under 3/8 inch. (extreme spread center to center)

Now I guess I can load some more, go out at high noon, or try and use another persons chronograph to compare data, or I could believe that my rifle is just faster and more accurate than anybody elses? The primers were not really flattened, and the bolt lift was good.

Question: Anyone else find that Chrony reacts differently to white-tipped and red tipped bullets?

thanks

My rule of thumb for magnum primers is to consider them the equivalent of a grain of powder. That is to say, if I have a max load with the 210, I'll drop at least a full grain switching to 215's.

My experience with RL powders is that they recommend 210's. I have found few loads improved by using magnum primers.

You should pick up no more than a 100fps with your extra two inches of barrel, particularly 24" to 26". This means you are as much as 300 fps over the book. I'd be very leery of your pressures at more like 300fps over the book.

I'd suggest dropping the 215's and increasing your powder charge in half grain increments from your current loading and seeing what your groups and velocities do. You should get a better understanding of your pressures as a base line.

I hate to be an alarmist, but IMO you are in dangerous territory with your load. Ku-dude

I have a chrony that is fussy. BUT someone here said put a piece of frosted scotch tape over the holes where the light sensors sit. This seemed kind of crazy but..........the idea worked. My chrony now seems much more consistant in all light conditions. Especially bright light with blue sky which used to be hard to work with. Just an idea that might work for you too???!!

Appreciate the response, I too was alarmed when the chrony showed 200-300 fps over expected velocity, which is 100-200 fps when allowing 100 fps for 26 inch barrel. My consternation was that the chrony readings for the redtipped 120 grain nosler baltips dropped 200 fps when canting the chrony into the sun, while the whitetipped accubonds went UP in indicated fps.

Nonetheless, I do not need or want to be above the max pressures of 60,000-62,000 psi for any load, accurate or not.

So I will do as you suggest: drop back a grain, try some nonmagnum primers, and then creep back up to max load with chrony speeds taken at high noon.

Jameister

I will put the frosted tape over the plastic openings. WOnder if that is a universal fix why the folks at chrony do not frost all their plastic lenses?

Any idea why this works? is it possible that the early or late sunlight angles reflect ahead or behind the bullet path into the sensor? perhaps redtipped bullets reflect differently than white tipped bullets?

here is another good idea that works very well.. Color your bullet with a black magic marker.. This seems to help most of the times...

6.5 Bandit