Distance to chronograph

[higgins]

The following is from the SAAMI voluntary industry standards for center-fire rifle ammunition; the same wording is included in the SAAMI standard for center-fire pistol and revolver ammunition.

A table of time of flight vs. velocity should be used to determine instrumental velocity at 15
feet (4.57 m), nominal, from the gun muzzle (not required when using direct reading
equipment).

I take this to mean that the chronograph should be fifteen feet from a centerfire rifle or handgun. I started using my Chrony years ago at about 8-10 feet for rifles and 6-8 feet for handguns. I set it at that distance because I figured it would do away with most of whatever variables were introduced by muzzle blast as well as ejecta like burned powder particles, while getting close to the "muzzle" velocity. Only a couple of years ago did I check into the SAAMI spec. after someone noted that military velocity measurement standards were at fifteen feet, if I remember correctly (and that's a big "if").

Anyone experimented with actual velocity measurement at various distances to the chronograph with a given rifle or handgun load? My measurements are close enough for my use, such as detecting overpressure loads, and if I want to duplicate a velocity with a different powder I can just set my chronograph at my 8-10 foot distance used in the past. A couple of years ago I did start setting my chronograph at fifteen feet for rifle loads but still use a closer distance for handguns. Now I have to remember to record the approx. distance to chronograph in my notes.

[nhyrum]

I've always taped out 15 feet from the muzzle. Easy for rifle because it doesn't move much from a bench/bipod and paced out roughly 15 feet for handguns. Handgun velocity isn't super critical to know the actual muzzle velocity, but just know if your using a ballistic calculator, velocity at 15 feet isn't the true mv, which can be interpolated, but will be close enough for most everything

I've heard of people having a second Chrono out at say 100 yards or 200, but that's mostly to true up the bc

Sent from my SM-S918U using Tapatalk

[murf205]

I had too many false (muzzle blast) readings with my 3 chrony's at 10 ft and better results with them and my Oehler model 10 at 15'. Sunshine (glint) made a bunch of goofy readings as well so I now use a Magneto Speed for rifles and put the chrony's as far away as the cord will allow for handguns. It really doesn't matter as long as you test at the same distance every time.

[Hick]

I've always been happy with my chrony results at three long steps from the end of the muzzle (probably around 10'). Never had any muzzle blast effects. Actually, if your purpose is to compare one load to another in the same firearm, you need to just decide and always use the same distance.

[racepres]

I will say that most of my readings are at 10'
I did get false readings and Errors with the 221 Fireball, 7TCU, and absolutely, the 357 Fireball!!! (357 Herrett), So 15" with those..

[Cast10]

Min - 10
Max - 12
Pact PC2

[Hossfly]

I set mine up at 10’ and hope I don't hit it again.

[Hannibal]

I use a Magnetospeed so it's not an issue. Neither are lighting conditions. Yes, it's a bit more expensive but given the cost of components and wasted range trips it doesn't take long before it pays for itself. Plus I can stay behind the firing line which is a big plus.

[billmc2]

All my measuring so far, has been with hand guns. I've used a tape measure and set the chronograph 12 feet from the muzzle. Maybe I should move it back a couple of feet more.

[ioon44]

I set up my Labradar to get the first reading at 10', really nice not to have anything down range to destroy.

[Bigslug]

I'm using a highly scientific method factoring in the length of the Oehler's cables and the un-eveness of the ground in front of the shooting bench. In other words, I set it out there where I can get a clean line of sight through it and the cables can run on the ground rather than hang suspended where their weight will pivot the top of the tripod around. It's more than ten feet to the first screen, but less than 20, and that probably fluctuates within that by as much as 4 feet on any given day. With a good load going over the chrono on different days, the load seems to deliver consistent numbers within that random spacing. If there IS a critical distance, I don't seem to be at either extreme of it.

[charlie b]

Mine I used to set up at around 10ft. Never had an issue (except when I shot it :) ). Rifles and pistols did well at that distance. As long as light was good it always got a good reading.

Have had a labradar for several years now and would not be without one.

[Rapier]

I normally setup 10' off the muzzle, approximately, give or take 5'. Never seen a real difference give or take. If working on duplication, I do a by the book setup with loads in 1/10 grain increments. I did run a Federal National Match 168 grain, load duplication setup once, for my 308 load, to shoot at 500 meters from my AR-10T 308 with the Springfield etched reticle scope mounted, worked like a champ.

[Larry Gibson]

With the M11-61 Oehler I used a 10' distance from muzzle to the start screen.

With rifles I use 15' with the 2' spaced screens of the Oeler M35P and 10' for handguns. I also use the same with the Oehler M43 PBL as the muzzle to start screen and screen spacing have to be input into the system. The M43 then converts the screened velocity to muzzle velocity.

With the M35P and my suppressed rifles or handguns I use 1' from muzzle to start screen as there is no muzzle blast to give a false reading. That also gives very, very close to actual muzzle velocity.

With the MagnetoSpeed the bayonet is attached to the barrel as mentioned.

[country gent]

I use a lab radar now so its easy to set up right beside the rifle. Before I had a pact professional and used the recommended 10' distance. The one thing I do do is to "prove the set up to make sure its reading right. I use a single cock springer air rifle and the same lot of pellets, I know what they produce velocity wise if the new set up isnt close theres something off. I also keep the results of the 5 shots from the rws pellet rifle with the days testing

[fredj338]

I'm 9-10ft for handguns & 14-15 for rifles with my Oehler. Labradar is on my want list.

[35 Rem]

I never measured the distance for setting up my chronograph but am sure it would fall somewhere between 10 and 15 feet. What little velocity is lost between the muzzle and that distance has no practical significance in my opinion. Anyhow so long as you are measuring at approximately the same distance each time is all that matters.

[44Blam]

Once shot the back screen of a chrony with a full house 44 mag. It was dramatic.
Now I use the labradar...

[lotech]

Until I got a LabRadar several years ago, I didn't measure the muzzle-to-screen distance with other chronographs that I used for about thirty-five years. Eyeballing it at approximately 10-12 feet for rifle and handgun worked fine. I can't see an exact distance as critical for meaingful results.

[Gobeyond]

Me too I eyeball it to 10 feet. But for pistol I go 6 inches. It’s says so in the directions. Seems to work ok. It’s easier to mess up with a pistol and ten feet is good for rifle especially scoped. But I just use it for the velocity reading.

[kevin c]

I use ten feet for pistol cartridges. That’s driven by that distance being the unofficial standard used at action pistol matches.