How beneficial is a chronograph?

[jmr40]

How beneficial is the speedometer in you car? As long as you stay close to starting load data, or drive like a 90 year old lady you'll probably never need either. But without a chronograph or speedometer, you have no idea how fast, or slow you are.

Once you start getting above mid level loads you will often find that you are getting speeds much faster than the loading manuals suggest. You could be over max based on pressure even though you are 2-3 grains below what is listed as a max load in the manual. While it isn't perfect knowing the bullet speed is the easiest way to predict pressure.

With certain powders and bullets my 300 WSM is getting 100 fps more speed than the manuals list with 2 gr less than a max load. I have to drop down 3 gr below what is listed as a max load to be safe. No way I'd know that without a chronograph. Other powders will still be below the max speed listed even with a max charge of powder.

Traditional pressure signs many try to use don't show up until you hit 70,000 psi. It is like driving a car without a speedometer, but a warning light that comes on when you hit 100 mph. You don't know you're too fast until you are WAY too fast. A chronograph or speedometer lets you know when you're approaching the speed limit before you get there.

I'm not one to hot rod my loads and go over the max loads suggested. But at the same time I have no use for loads 200-300 fps slower than typical factory loads either. If I buy a 30-06 I don't want 300 Savage speeds, if I did I'd have bought a 300 Savage. I don't have to shoot my 30-06 at 2500 fps to get excellent accuracy, there are loads at 3000-3050 fps that will shoot just as well that are every bit as safe to shoot. But I'm not gonna play around with loads approaching 3000 fps in a 30-06 without knowing exactly what speeds I'm getting. If I start approaching 3100 fps, then I'm probably getting into the danger zone and it is time to back off.

You don't need a high end chronograph, some of the sub $100 units are accurate to within 15-20 fps, that is close enough. At that price it is not a bad idea to own one.

 

[taliv]

last week I shot a new rifle, new caliber for the first time past 100 yards. I chrono'd (see 2nd page of my thread on barrel break in in rifle country) at 100 and then backed up. The large impact on the 12" plate was the first round past 100 yards. The distance was 541. The smaller impact was the 2nd round at 1009 yards. (I badly missed my wind call on the first round). That's the value of a good chronograph (and ballistic calculator)


if you can't use a chronograph, there is an alternative. You can back up to about 300-400 yards, and measure the drop, then calculate your speed. However, you have to have a high degree of confidence in your ability to shoot accurately.

 

[Newtosavage]

I use one for two reasons - neither of which are related to accuracy.

First, I want to know how my loads compare to published data, and second, I want to be able to calculate ballistics. Using MV and published ballistic coefficients for each bullet, the Hornady ballistics calculator has been darn close when looking at bullet drop over distances.

Several of my loads are within an inch at 300 yards using this method. Saves me a lot of walking and wasted loads.

 

[Newtosavage]

JMR40 - you raise a good point and something I need to learn more about.

I'm developing loads for my 7x57, but it has a rather short 18.5" barrel and my velocities are usually 150-200 fps. slower than published data. Are you suggesting that it's safe for me to keep increasing the charge until I approach those published MV numbers?

I've seen no signs of case pressure in anything I've loaded. I'm wondering if the shorter barrel is keeping not only the speed low, but the pressure too.

Thanks.

 

[Bart B.]

Compared to a barreled action fixed in place like a universal receiver/barrel testing ammo to SAAMI specs:

Rifles hand held against ones shoulder will have lower average fps numbers and higher ES and SD numbers. If several people shoot the same stuff, a 50 to 100 fps spread in average muzzle velocity and a 15 to 30 fps spread in SD and ES numbers.

If the rifle's placed on bags and shot in free recoil touched only by the shooter's finger on its trigger, there'll be the lowest fps numbers but ES and SD numbers may be the same but sometimes lower or higher.

When the rifle's shot slung up in prone, such as the F-class position resting on something, average fps numbers will be closer to a fixed barreled action and ES and SD numbers will be much better, too.

Unless your barrel has bore, groove and chamber dimensions as the one used to get published data and your component lots are also the same, the velocity numbers you get with other component lots will be different that published data.

 

[taliv]

Rifles hand held against ones shoulder will have lower average fps numbers and higher ES and SD numbers. If several people shoot the same stuff, a 50 to 100 fps spread in average muzzle velocity and a 15 to 30 fps spread in SD and ES numbers.

i'm pretty skeptical. i will test this next time i go to the range.

just to be clear, you're saying if i just hold a rifle up standing and vary the amount of resistance in my shoulder i can change the velocity by up to 100 fps?

 

[Morrey]

Accuracy minded and precision oriented folks need one, especially when working up new loads. Some fly by the seat of the pants reloaders wouldn't need one simply because they are not real precision conscious.

I even chrony factory loads just to see what the big companies are doing out there. You'll be surprised what a variation you'll see.

Its not a very big investment after all....some are less than the price of three or four pounds of reloading powder.

 

[Bart B.]

I'm saying if several folks just hold a rifle to their shoulder shooting it as it rests on something atop a bench, up to 100 fps spread in average fps numbers can happen. I did shoot a few round standing to compare them to slung up in prone; those shot from prone went about 20 to 30 fps faster.

I've seen as much as 60 fps; a couple others have seen about 100.

Me shooting a benched 12 pound 308 Win rifle against my shoulder with little to a lot of pressure was good enough to see about 50 fps spread.

 

[Jim Watson]

My main use for a chronograph is handgun power factoring. It lets me load to factory equivalent for defense practice and to the power factors required for different IDPA Divisions.

I have also used it for rifle ammo.
A BPCR has a higher trajectory than hv smokeless, uniform velocity is essential for accuracy at even midrange. Decent BP ammo has single digit standard deviation , good BP ammo has single digit extreme spread. But you don't get it without good equipment and technique.

In smokeless, my results with published BC are not as dismal as rcmodel says, though not as good as taliv got. Chronographing also takes care of variables that show up in velocity, things like component lot variation, barrel differences, and the Bart Effect.

 

[Newtosavage]

So Bart - what you're saying is that folks who are sighting in with a Lead Sled can expect to see a change in POI when they shoot the same rifle standing up with a hunting coat on, right?

 

[cougar1717]

I think the chrono is a useful tool, but not something that most people use often. It's a check; an objective test that holds no feelings. They are useful to get an idea about terminal ballistics, power factor, or how much surplus powder is required to get to a velocity window.

I once had a rifle that grouped well but recoiled incredibly hard from "specially formulated" factory ammo. I also worked up some handloads to see what it would do. Using extruded powder, I worked up a load that had less perceived recoil, better accuracy, and had about 150 fps more velocity than the factory-stuff-it-full-of-ball-powder cartridges. Before a chrono, there was no way you would have convinced me that my handloads were faster.

 

[rabid wombat]

I use mine to validate my reloads. Just as I measure COL, and powder throw weigths - I chrono the loads. Just another check in the system.

 

[Dudedog]

I reloaded without one for a couple of years.
Sure am happy I bought one though.

 

[spitballer]

Highly recommend a chronograph for load development as long as the tempting velocity figures don't cause the reloader to abandon his/her rational pursuit of accuracy.

 

[hdwhit]

Chronographic Need

I loaded for years without a chronograph. And everything I loaded still went "bang" and the bullets landed somewhere in the vicinity of the target.

When I started trying to reload the 5.7 mm Johnson (a/k/a/ 22 Spitfire), I invested in a chronograph. This was largely so that I could determine whether each incremental increase in powder produced an increase in velocity - a clear indicator the maximum load is being reached.

I also found it interesting to see the differences between what the manuals predicted for velocity and what I actually got. This was particularly helpful in my .223 Remington loads since I shoot them out of a Ruger Mini-14 which has an 18 inch barrel rather than the 22 or 24 inch barrels used by most of the companies that write the manuals. For me, it worked out better to stay at the faster end of the powder burn rate (i.e. IMR 4198, IMR 3031 and Winchester 748) to get the best performance out of the shorter barrel.

 

[Andrew Leigh]

I have a different take on this., I like technology and I like to use it. The Chrony argument is the same as the Quickload argument, some will simply never see the benefit. I took the plunge and the combination of the two has saved me plenty of my hard earned cash.

We use components that are pretty well defined and within SAAMI specifications. We carefully select our bullet of choice (some even batch weigh them), then trim cases to precise length, weigh our powder to within 0.1gr. and measure COL to fractions of a inch (mm). Then when we go to the range we feel no need to measure the fruits of our labour to confirm our consistency.

When using a chrony one must be careful to note that 3 or 5 rounds hardly constitutes a statistical group so we must be mindful of this.

A chrony tells me a couple of things;

- The consistency of my reloading practices. I remember shooting a batch of 300gr. .375 loads at 8.5fps SD. It was the last firing before annealing, I had not annealed before. I then performed my first annealing routine and with the same loads my SD opened out to 29fps. When seating the bullets I could feel that potentially some were tighter than others. The chrony confirmed this through large speed variations.

- The speed of my loads relative one batch to the other.

- The effect that approaching the lands has on speed / pressure.

- Using ballistic software to model pressures based on speed. Yeah I know what the naysayers will say, let me say that some reference point is better than none. I also use visual signs.

- Allows me to calculate bullet drop rather than having to physically measure it.

- It allows me to see the effect from bullet to bullet with the same load. Not all same calibre bullets are created equal.

- It removes a lot of guesswork.

 

[Bula]

Nice to have if your a numbers guy. I mainly shoot pistol. Bought one and rarely use it. Still nice to have. More educational for me than anything. Didn't make my shooting any better.

 

[SSGT PRIDE]

Dylan PM me...I got a chrony on a HEAVY tripod thats never been shot(LOL!!!) and spare sticks/Aluminum rods even if you do...F1 shooting Chrony I think is what they call it.

I'm in Central Ky as well and asking 50$ complete

Got a magnetospeed last year here that I love and will never go back to the F-1

 

[Newtosavage]

It allows me to see the effect from bullet to bullet with the same load. Not all same calibre bullets are created equal.

Good point. I was stunned to discover how many fps difference there were between different .308 caliber bullets of the same weight! I would have never guessed that.

The first "best" use of my chrono was to get speed at distance so I could determine what range a particular round was suited for. I was shooting some russian made 7.62x39 154-grain soft points, and I knew the MV but had no idea what the BC of the bullet was, and wanted to see what they were traveling at the 200-yard target. So I set my chrono up at 200 yards a few feet in front of the target and shot a string over the top of it. I was able to get a velocity at that distance, and then roughly calculate the BC for future reference. Very useful IMO. I could have done this with bullet drop (maybe) but with the chrono, I had real numbers right away.