Chronograph distance?

Gents, I am not exactly sure what the "standard distance" is to shoot my rifle through my chronograph? How far away? 6 feet, 8, 10? All my hunting reloads with the exact same bullet, powder, powder weight, primer, brass, and barrel length, run 50 to almost 100 fps slower than the book listed!

Instructions for chrono give recommended distance. It has to be far enough away to clear the muzzle blast. Are factory loads slower also? What about .22 ammo?

I get mine as close as I could without errors. But if you can swing it do yourself a favor and get a magneto speed. Best thing I did for gathering data.

For a "shoot through", I ran my old one at 10' in front of the muzzle.

Since you didn't list any of your load or rifle info, here are some examples.

Lots of variables can cause velocity differences.

Placement of chrono
Chrono itself
New barrel/broken it barrel
Tight bore vs. loose bore diameter
Chamber dimensions/reamer design/throat length
Twist rate
Rifling count/shape
Brass content
Powder lot
Primer lot
Bullet bearing surface length
Recoil management by shooter
Ambient air temps/powder temps or temp sensitivity

Even though most chrony's say 10' for standard cases and 15' for magnums, I found my happy medium measured at 15' for everything.
Closer than this with certain cartridges and readings would go 'heywire'.

My only issue, be sure to NOT try several different bullets in the one rifle........I did this, and 1 of them shot MUCH lower than the rest and I hit the chrony, destroying it.

Cheers.

Your loads will be different than the book because you are shooting a different rifle and as Lance said above, there are many variables. As Capt Barbossa said in Pirates Of The Caribbean "Har, they be more like guidelines".
It is more important that you place your chrono far enough that it is not affected by muzzle blast and placed the same each time you use it. For example with my old Oehler, the first screen is set 10ft from the muzzle and the second is at 20ft so I am reading velocity 15ft from the muzzle. It never matches book values but I can see how my loads compare to book values and more importantly to each other.

Thanks, I am shooting at 6-8 feet, which doesn't blast the screens. Shooting a Weatherby VG in 6.5 CM . I see from the data and computer target they sent, that they shoot to screen 1 @ 7 feet.

Glenn Tullius,
My Freedom Arms was always like that.

Yep...10-12 feet with my rifles....about 8-10 with shotguns...
Don't want the shotgun wads hitting the chrono either...it will smash'm up pretty good.....same with sabot in mzldr.....

Around 10' on rifles

12ft never an error

With a chrono on a tripod, is 10' enough for magnum muzzle blast or should the tripod be weighted or staked, so that it doesn't topple?

I use an Oehler 35P. On the wires that lead from the screens to the chronograph I wrap a piece of black electric tape every foot. At the 10' mark I placed a piece of red electricians tape. It is very easy to accurately place the screens at 10' each time I set the screens up.

The only time I ever had a problem was with a 458 SOCOM that had a brake which had (some) holes facing forward. Other than that, 10' seems to be a good distance for screen placement.

CO_Guy said:

With a chrono on a tripod, is 10' enough for magnum muzzle blast or should the tripod be weighted or staked, so that it doesn't topple?

Click to expand...

I've shot 300RUM through mine and never weighted it down