estimating velocity

[KDubs]

I bought my chrono years ago, like 20, for archery and bow tuning.
 Ill be trying it on my front stuffer today.  I'll let ya know .
 needs to be atleast 15 ft in front of ya, I saw a post somewhere for making baffles to stand up in front of the chrono to protect it from the blast.  not sure thats necessary at 15 ft.  guess we will see......
kevin

[Winter Hawk]

My chrony is 28 years old now, a gift from my Sweetie.  I tried it with my muzzle loader and got over 17,000 fps!  I thought the patch right behind the bullet made for the erroneous reading.  That was at 10' from the muzzle.  What John suggests about putting attaching paper to the frame is great!  You could make an aiming point on the paper so the ball would not hit the chronograph.  Good idea, John!
 
~Kees~

[RobD]

...  What John suggests about putting attaching paper to the frame is great!  You could make an aiming point on the paper so the ball would not hit the chronograph.

Ya need to be VERY CAREFUL with where to aim with regards to "screen" type chronos - too many folks aim either dead center or low and wind up trashing the chrono.  At such a short distance 'tween muzzle and chrono, bullet POI will be LOW, sometimes drastically low, ask me how I know this ....

[Bigsmoke]

One day I was chrono testing a 2 bore rifle, the projectile weighed 3,500+/- grains and we were starting out at about 350 grains of Fg Goex.  The chrono was set about 20 feet ahead of us and I was shooting it offhand.
I must admit, I was a bit intimidated by this behemoth and pulled down a tad as I pulled the trigger.  Well, maybe more than a tad, as the bullet hit the darn chrono and destroyed it.  Hah, it took a while for all the pieces to hit the ground.
I should have fired it once to get the feel of it before shooting over the chrono, but I was in a hurry and as a result,  severely mutilated it.  Oh well, live and learn.
John (Bigsmoke)

[Winter Hawk]

Ya need to be VERY CAREFUL with where to aim with regards to "screen" type chronos - too many folks aim either dead center or low and wind up trashing the chrono.  At such a short distance 'tween muzzle and chrono, bullet POI will be LOW, sometimes drastically low, ask me how I know this ....

That is why I suggested putting an aiming point on the paper, so a person doesn't shoot too low and destroy the chronograph.

And John, I can't even imagine the recoil of 350 grains of Fg pushing a 3500 grain projectile!  How is your shoulder now, after all the years of punishment you gave it? 

~Kees~

[Bigsmoke]

And John, I can't even imagine the recoil of 350 grains of Fg pushing a 3500 grain projectile!  How is your shoulder now, after all the years of punishment you gave it? 

Surprisingly enough, the right shoulder is doing OK, considering, as you put it, all the years of punishment.
Sorry to say, however, that the left shoulder is the one bothering me, rotator cuff ripped and arthritis and bursitis diagnosed and treating it with shots.  Plus tendonitis in the left elbow.  Them "itis" brothers seem to be out to get me.  Oh well, I guess they are right when they say that getting old ain't for sissies. 

John (Bigsmoke)

[RobD]

Ya need to be VERY CAREFUL with where to aim with regards to "screen" type chronos - too many folks aim either dead center or low and wind up trashing the chrono.  At such a short distance 'tween muzzle and chrono, bullet POI will be LOW, sometimes drastically low, ask me how I know this ....

That is why I suggested putting an aiming point on the paper, so a person doesn't shoot too low and destroy the chronograph.

And John, I can't even imagine the recoil of 350 grains of Fg pushing a 3500 grain projectile!  How is your shoulder now, after all the years of punishment you gave it? 

~Kees~

No, that might spell disaster because at 10ft to 15ft or so there can be a Huge difference 'tween bore sight and actual sight ... and this WILL happen with long guns that sport high sights.  Been there, didn't do the bore sight, bullseye into the chrono face.  In the best of worlds it's bore sight that should be employed with all screen chrono's.  Easy to do with any long gun that can have an open breech (bolt, break open, etc), difficult for muzzleloaders and other "closed breech" guns.

[Winter Hawk]

I was looking in in the back of my 2023 Dixie catalog the other day and noticed an article on estimating bullet velocity.  I think the Lyman handbook with empirical data is probably more accurate but this is another source for "guesstimating" how your loads are doing.

~Kees~

[RobD]

Sticking in one of those muzzle bore lasers will quickly show where the bbl needs to be pointed at the chrono.