just set the screens a bit closer together

Heh . . . yeah.

In my case, I achieved a lower velocity.

I hadn't seated the sensors fully on their rail, and a velocity I expected to approximate 2700 fps turned out to be in the mid 2400s.

I have a chrony and one time I failed to unfold the tin box all the way! The results was a reading over 100 fps. higher than It should have been. Not unfolding all the way caused the sensors to be closer together.

Live and learn!

Hip

quote:

I have a chrony and one time I failed to unfold the tin box all the way! The results was a reading over 100 fps. higher than It should have been. Not unfolding all the way caused the sensors to be closer together.

+1 Yep happened to me. I thought I had found a new super load.

Just a 1/8" spacing error on the screens makes over a 1% difference in velocity if the screens are spaced at 12 inches. A half-inch spacing error adds (or subtracts) 125 fps at a nominal velocity of 3,000 fps. Screen spacing error, from whatever cause, has the potential to create much greater velocity error than the + or - 1 tick in the typical 1MM per second clock/counter of the chronongraph.

quote:

Originally posted by ramrod340:

quote:

I have a chrony and one time I failed to unfold the tin box all the way! The results was a reading over 100 fps. higher than It should have been. Not unfolding all the way caused the sensors to be closer together.

+1 Yep happened to me. I thought I had found a new super load.

Me too Paul!
My bro set up the chrony a couple weeks ago and I knew there was an issue when my 212 gr ELD-X from my 300 RUM was going over 3400 fps!!!! "super load" Haha
I opened the bolt and walked up for a look and noticed exactly that, not opened all the way.
3150 fps, there... that's better!

Zeke

It's hard to beat the formula: Distance = rate X time. Or, rate = distance ÷ time.

Can the added speed be seen at longer ranges?

I found it to fail that test.

I've used a Chrony for years and have modified mine so the two halves are slotted on the hinge pin. When a session is not going so well, f...k it I can just adjust the Chrony to read the velocity I'm looking for and at least I go home from the range feeling happy

I'v always found it very difficult to set up my Shooting Chrony at the right height and getting it straight and level. I finally invested in a higher quality camera tripod that has 2 levels in the camera mount head. But it wasn't till I got the idea to leave my LaserLyte bore sighter in the rifle barrel while setting up the chrony.
With the rifle in a lead sled laser bore sighter installed and the laser dot set on my target I goto the Chrony and use my hand up as a screen for the laser dot. I can move the Chrony about till the dot is centered over the sensors and at the right height. I always remove the laser from the barrel before I get behind the rifle.
I haven't gotten a sensor error since I started using the laser to assist in the Chrony setup.

Just get a LabRadar and never look back.

Greenjoy,
Reminds me of a trip to the range and a guy was using a boresight. He forgot to take it outa the muzzle and let off a round-----barrel looked like an umbrella frame after that!

Hip

It is easy.

Shoot whatever rifle you desire, whatever the reading is, add 200 fps.

You never go home unhappy or scratching your head, makes for a great afternoon at the range.

Just hit one of the wires and see what it reads from then on! CURE: is replace them with dowels.

OR hit the thin plastic face with a bp patch will do about the same thing. CURE: put a 1/4" clear plastic in front of the face, that won't be damaged unless you put a bullet thru it.

There's a good reason those companies put the works in front of the muzzle!
So they can sell you another one!

George