Chronograph

[flyfish]

My wife gave me a Chronograph for my B-day.

So, besides finding out how fast a bullet goes with a paticular load, what do you do with it. :roll: Asked in a little more serious manner, how do you us the info you get from the cronograph to improve your reloads.

does that make sense? :roll:

 

[metallica]

LOts of info, You can compare the speeds of your loads with whats listed in the book. You will know something is wrong if there way different. You can tell when your getting to the max load by the speed of the bullet. And you compare the speeds shot to shot. This tells you how consistant your reloading is. If shot a is 3200ft/sec shot B 3000ft/sec and shot c 3300ft/sec, you know your not doing a good job reloading. Once you start using it youll think how did i ever reload without it....

 

[DrMike]

In addition to seeing velocities of the loads you develop, you can see the consistency of a given load by noting the standard deviation and the extreme spread of the load. These values are good indicators of potential accuracy, for if a load is consistent it has the potential to produce a consistent harmonic in the barrel and strike the same point of impact with each shot, providing shooting technique is consistent.

While a chronograph per se will not give you pressure measurements, the velocity will indicate when you are exceeding published velocities associated with a given pressure. This can keep you out of real trouble. As an example, I carefully developed a load for one of my rifles to note that it was safe. When I changed bullets to one with a longer bearing surface, even though I began with what should have been a minimum charge of powder, the velocity registered well over maximum. In point of fact, it was generating excessively high pressures and could have proven disastrous. My chronograph permitted me to avoid the problem.

Your wife gave you a fine instrument which can be a real asset in developing safe, consistent and accurate loads for your rifles.

 

[gunny1]

It will tell you many useful things. You can get a high and low velocity. It will tell you the extreme spread or ES(between the high and low velocity). It will give you an average velocity. And it will tell you your standard deviation or SD. The standard deviation will tell you how closely you loaded each bullet in comparision (ie. powder charge consistancy). All very useful information when working up an accurate load.

 

[gunny1]

Dr Mike said it.. We must have been writing at the same time. DIDO

 

[Antelope_Sniper]

These are all great questions:
What all can you do with a Chronograph?

Well first, it's a de-liar. In the old days many of the loading books were, well, just wrong. So it will tell you if that hot load is really hot, or not.

Statistics: You will be suprised how much your velocity will change shot to shot. Of course shooting is about reducing variables, so it's easier to identify the loads with the smallest spread between the high and low, and lowest standard deviation. i.e. the most consistant load.

It can also help you keep an pressure. An unusually high velocity might be the result of an unusually high pressure.

Sometimes you can tell when a rifle is reaching the end of it's usable barrel life, because as the throught erodes, the velocites will drop, and the standard deviations will start to increase.

Probably the most significate thing I use it for is personalized drop tables. I measure my velocities then go here:

http://www.eskimo.com/~jbm/calculations/traj/traj.html

And make my personalized drop tables.
I print the table in 25 yard increments out to 1000 yeards, with the drop and windage in MOA. I fold it up pocket size, so i can see 300 to 850 yards at a glance. Once you get good with a system like this, it will change the way you hunt. Next ridge over? No problem. Lase, wind, dial in, spotter watching the critter, and shoot.

After a while you will wonder how you ever survived without one.

 

[Antelope_Sniper]

I think all 5 of us were writing at once.
I guess that makes it a 5+

 

[gunny1]

Too funny... Well at least we know great minds think alike. Or rather, we were all were bored and surfing the net at the same time.

 

[gunny1]

Fly fish. Look at the target velocity you want to achieve. Load to the best of your ability. And look for the most accurate load with the smallest Standard Deviation. This is my suggestion


Antelope sniper. What else does that web sit have (eskimo). Do you have to join or is it just an infor web site?

 

[flyfish]

8) Thanks everyone!

 

[Antelope_Sniper]

Eskimo is just the Host. The site is for JBM Ballistics. They have a few interesting things such as calcualtions for recoil energy, and proper twist rate for a given bullet, Maximum distance calculator, and even a few alternative ways to calculate trajectory. Overall, it's a very useful site.