Chronograph help...

[Maverick1911]

I am thinking of getting a chronograph to test out some rifle loads..but to be honest, I have no idea what I am looking for when using one. I have always just zeroed at 100 yards and then adjust my dope data as I hit 200-300, etc. What exactly am I supposed to be looking for? And...what do I do with the data I acquire ?

 

[swampratt]

I have one if you want to use it..Accuracy is what you are looking for.
Many things will change the readings,,
You may get faster/ higher readings as the barrel warms up.. or as more fouling accumulates ..

What you want is accuracy small groups at the distance you shoot, who cares what the readings are to get there.

But like you stated to figure bullet drop at distances is what they are best served for..

I have shot through mine at 15 feet from the muzzle and at 100 yards to compare or compute bullet BC.

You better not shoot the chrony though...

 

[ASP785]

Its important to know your velocity if you are using a ballistic calculator. With that being said, velocity is secondary for me when using a chronograph. I am really interested in finding out how consistent a given load is. I will shoot 10 rounds through the chronograph and get the Standard Deviation and Extreme Spread of that particular load. The lower the SD and ES, the more consistent the load is. If I have an ES of 100, I know that my loads aren't very consistent round to round. That deviation will show up on paper as vertical stringing as distance starts to increase.

If you have 1 round out of a group of 5-10 shots that is an outlier, something could be wrong with just that round. If you have multiple rounds with large variations from the average, then something is probably wrong with your process. This is where it gets interesting. It could be the amount of powder, bullet depth, primer pocket size, neck tension....etc etc. You have to figure that out through load development. The chronograph will just give you the data to determine if the load is consistent from shot to shot.

 

[Maverick1911]

Gotcha....that actually clears up a lot. And I might take you up on that offer, swamp! But I'd probably borrow you for an afternoon on the range if you have time.

 

[Jcann]

I am thinking of getting a chronograph to test out some rifle loads..but to be honest, I have no idea what I am looking for when using one. I have always just zeroed at 100 yards and then adjust my dope data as I hit 200-300, etc. What exactly am I supposed to be looking for? And...what do I do with the data I acquire ?

If you're range is limited to <500yds I wouldn't concern myself with ES/SD too much. Naturally if you're shooting F class or tactial matches go for it. Most box stock rifles won't shoot accurately enough to notice high ES/SD at longer ranges and this doesn't take the shooter into account.

If you really want to get into the "hand loader" game you can always try OCW or ladder testing your hand loads. This is where the chronograph really comes in handy.

 

[swampratt]

You know I found my OCW a lower accuracy node for my .308 win.
The funny thing is it groups awesome to as far as I have shot it 300 yards but it is not the load that produces the closest fps between rounds.
It is 1/2 moa or better.. another funny worth mentioning, this accuracy node is not the best at grouping at 100 yards.
In fact it is around 1" but at 275 yards it is still 1"

I have had a couple loads that all bullet holes touch at 100y but shoot it at 200 and it went to crap. like 8"-12" groups.
That is why I never assume anymore.
This .308 is the only gun I have that acts this way.. my 30-06 and .243 follow the book.

You can borrow me and the chrony some time and we will go see what gives.

 

[Maverick1911]

I am going to load up some 77 grain pills and then take you up on that, swamp!

 

[dennishoddy]

I shoot outdoors, so the Chrono goes with me at most range trips when trying to get a handle on accuracy.

I shot my .270 Win Classic pre 64 at the range the other day with the Winchester supreme 130 grain, nickel case ammo.
Got 100fps + variation in ammo that cost $40 for a box of 20. Shot the Cheap Hornady 130 grain, and had less that 55 fps variation.

My reloads are typically 50fps or less variation.

A chrony is your greatest tool. I've had guys brag their rounds shoot a zillion fps because of some "secret" thing they have done.

Run them across the Chrony, and they put their tail between their legs, walking away in shame.

 

[swampratt]

Get some loaded up and lets go shoot somewhere.
Weekdays are best for me though during the day as the weekends and evenings are for the wife. Got to keep momma happy.

 

[Blitzfike]

A chrony is one of the best tools I use for working up loads with different powders. I use a lot of surplus powders and keeping track of the velocity in load development is an important step. I'm currently developing loads for a 50 cal wildcat based on 375 ruger basic brass (it hasn't been sized to a bottle neck case yet) Straight wall rimless case using .501 diameter bullets like the 500 SW or the 50AE or even my 50 beowolf. I am currently working with 440 grain cast gas checked bullets. So far the maximum load has been 90 grains of IMR-4895 with a 330 grain JHP. I am doing a ladder with the 440 grain cast starting with 70 grains of 4895. No data out there for this one, it is called the 50 Thumper for obvious reasons.