Chronograph Benefit

[Phil3]

I am new to reloading, and load development, and would like to know just how much benefit there is to having chronograph. I know they measure velocity, but would like to understand more of what benefit they can provide to the shooter in the development of more accurate loads. I am willing to buy a unit, just want to be sure I am using it to its full potential. I am shooting an AR15, and will be shooting an AR-10, and a 6mmBR, at 100, 300, and 600 yards and am after the best accuracy possible from a bench or prone.

- Phil

 

[Don]

I am new to reloading, and load development, and would like to know just how much benefit there is to having chronograph. I know they measure velocity, but would like to understand more of what benefit they can provide to the shooter in the development of more accurate loads. I am willing to buy a unit, just want to be sure I am using it to its full potential. I am shooting an AR15, and will be shooting an AR-10, and a 6mmBR, at 100, 300, and 600 yards and am after the best accuracy possible from a bench or prone.

- Phil

Plenty of winning competition shooters do not even own a chronograph, and many that do own chronographs only use them periodically.

I feel they are like alot of shooting tools, they enhance ones knowledge of exterior ballistics and other small details of the shooting sport, but are not an absolute necessity...............Don

 

[jackie schmidt]

It Depends

I use my 35p Chronograph quite often. Just last week end, I did a test on the new BRX 8208. Only a good Cronograph will tell you exactly where you are at various powder weights.

There is a lot of general knowledge that can go along with using a Chronograph. For instance, when I start out with an entire new set-up, a Chrono lets me know where I am at right off the bat.

For instance, when I developed my 30PPC a while back. I knew from other knowledgable shooters experience that 3000 fps should be the top end velocity node. I simply loaded it up untill it hit that, (watching for pressure signs), and tuned down from there. Without a chronograph, I would have no idea whether I was at 3000, or 2800.

I did exactly the same thing with my 30BR's.

If I change a powder lot, or to another powder, the 35p tells me exactly where I am at at all times.

Of course, if you are just tuning for accuracy, or agging capability, you sure as heck don't need a chronograph. I just look upon it as a tool that allows me to learn as much as I can. .........jackie

 

[Larry Elliott]

A chronograph is a good learning tool. I used to shoot with a very intelligent man (PhD in microbiology), and he'd tell me that he'd loaded his hunting rifle to such and such velocity based on what a manual said that velocity would be with a certain powder, charge, etc. When he finally broke down and bought a chronograph he was amazed to discover that his velocities and those in the manuals seldom came close to agreement. He was amazed by that and a few other things he learned shooting over his chronograph.

For longer range shooting you'll be able to see which loads produce the smallest extreme velocity spreads or standard deviations which should reduce vertical stringing at longer ranges.

A chronograph is also useful to help determine top safe pressures. If a certain incremental increase in powder charge produces a certain increase in velocity up to a point, then the next incremental increase in powder charge gives a much greater velocity increase or a much lower velocity increase you may well be treading on thin ice. The velocity can go WAY up or hardly change with a large increase in chamber pressures when a too hot load is fired.

With AR's where maximum velocities are pretty well known (for the heavier bullet weights at least) within maybe ±50 fps, if you're shooting a load that's producing 100 to 150 fps lower or higher than expected it's time to start looking for what's going on. Hard to tell without a chronograph.

Reloading without a chronograph is sort of like building engines without a torque wrench IMHO.

 

[BenKeith]

As mentioned, great learning tool and takes the guess work out of what your loads are doing. The main thing is you must keep very good records of each load and pay attention to all the little details as you're building loads to get the most benifit. You see what causes velocity spreds and learn what it takes to keep it down.

Are they needed for reloading, NO! Would they make enough difference in building accuracy loads to warrent the cost, probably not. Do they help you understand what's going on, YES! For as cheap as they are, unless you are on a tight budget, they are neat little tools that if nothing else lets you know just what your velocities really are for different loads. Very seldom are they what you read they should be.

Other than when building loads, I seldom ever mess with mine. I figure the fewer times I use it, the fewer chances I have of putting a bullet through it. Trust me, that does happen.

 

[Clark]

If you think that peak pressure can be inferred from a chronograph, there is a place for you as the current white house administration's fantasy czar.

I have owned 4 chronographs, and I handload for 19 Badger .222, .223, 22-250 .243, 25acp, 6mmBR,.243Win, 25/35, .250/3000, 257 Roberts AI, 260Rem, 6.5x55, 270, 7x57mm, 7mm Rem mag, 32acp, 32sw, 32S&WLong, 32-20, 30 Mauser, 7.62x25mm, 30-30, 303Sav, 300Sav,.308, 30-06, 300 Win Mag, 7.5 Swiss,7.62x39mm, 303Brit, 7.62x54R, 8x57mm, 338WM, .380, 9x19mm, 9x23mm, 357Sig,38special, 357 mag, 38sw, 40sw, 10mm, 10.4mm, 44 mag, 45acp, 45Super, 460 Rowland, 45acpRifle 45Colt, .410, 45/70, and 12 ga.

The chrono is good for internet bragging.
My .223 will do 4200 fps with 18 gr Blue Dot 33 gr Vmax moly.

 

[Boyd Allen]

A chronograph is indispensable for putting together drop and wind drift tables, and while this does not relate to raw, how small is your group, accuracy, it does matter quite a bit for long range hunting, where knowing how many clicks to adjust your scope for a given distance, can be invaluable.

Another thing to ponder is that, contrary to what one might think, velocities do not necessarily increase in a linear fashion as powder charges are increased by equal, small increments. Some believe that a range of loads within which the velocity does not seem to respond in a linear fashion may be a good place to look for an accurate load that is not too demanding of perfect charge weight uniformity.

Additionally, there are those that believe that for a given barrel, and bullet, that accuracy is velocity specific. In that case, a chronograph is a valuable aid, and yes, I do think that within a given narrow range of burning rates, that there is a rough relationship between velocity and pressure. The exception being, when fast powders are used for squib, or cast bullet loads, which I believe the previous poster was pointing out in an oblique fashion in his closing sentence.

 

[Big Al]

After reading all these posts, I no longer wonder why my chronograph gathers dust on the shelf. Perhaps the poorest money I have ever spent on shooting gear.

 

[Larry Elliott]

If you think that peak pressure can be inferred from a chronograph, there is a place for you as the current white house administration's fantasy czar.

I have owned 4 chronographs, and I handload for 19 Badger .222, .223, 22-250 .243, 25acp, 6mmBR,.243Win, 25/35, .250/3000, 257 Roberts AI, 260Rem, 6.5x55, 270, 7x57mm, 7mm Rem mag, 32acp, 32sw, 32S&WLong, 32-20, 30 Mauser, 7.62x25mm, 30-30, 303Sav, 300Sav,.308, 30-06, 300 Win Mag, 7.5 Swiss,7.62x39mm, 303Brit, 7.62x54R, 8x57mm, 338WM, .380, 9x19mm, 9x23mm, 357Sig,38special, 357 mag, 38sw, 40sw, 10mm, 10.4mm, 44 mag, 45acp, 45Super, 460 Rowland, 45acpRifle 45Colt, .410, 45/70, and 12 ga.

The chrono is good for internet bragging.
My .223 will do 4200 fps with 18 gr Blue Dot 33 gr Vmax moly.

Clark, I'm happy for you that you load for a whole bunch of calibers, and if you think that a chronograph can't assist in letting a handloader know when max pressures have been exceeded congratulations is all I can say. You're the one living in a fantasy world. If you've ever chronographed loads where an incremental increase in the powder charge either didn't give an increase in velocity or a decrease in velocity you'd know what was meant.

I've done it, and had it happen when the book maximum charge hadn't been reached. Makes a guy want to reconsider increasing the powder charge a bit more to get that last few ft/second.

 

[Clark]

Not only can you not tell absolute pressure from chrono, absolute pressure is not important, the threshold of long brass life is important.

So YOUR fantasy world is two steps from reality.
My guess is that you are still using load books.

223

308 necked to 243

 

[Larry Elliott]

Not only can you not tell absolute pressure from chrono, absolute pressure is not important, the threshold of long brass life is important.

So YOUR fantasy world is two steps from reality.
My guess is that you are still using load books.




Clark, I really do think that you need to learn to read English, and get over yourself. I never said that absolute pressures could be determined by using a chronograph. What you can tell is when you've gone over the top or are about ready to go over the top.

Blowing primers only proves that you don't know where to stop, and like to break things. I've blown a few primers in my time, and find that it's proved nothing except that the load was WAY too hot for my rifle.

As for book loads I do have most of the books, and consult them for certain things. I've mentioned some of my loads to "experts" and they've indicated that they'd like to be notified when I'm shooting because they don't want to be in the same county.

Does blowing primers impress your friends, or do you just do it to entertain yourself?

 

[Clark]

.. if you think that a chronograph can't assist in letting a handloader know when max pressures have been exceeded congratulations is all I can say.
...

I never said that absolute pressures could be determined by using a chronograph.

..

The 1889 Mauser case head design, when built with a large Boxer primer and shot in a strong rifle is good for ~62kpsi sustained with factory and ~ 65kpsi in Handloads for one rifle.
That would include 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 25-06, 260 Rem, 6.5x55 [US brass], 270, 7mm-08, 7x57mm, 280, 308, 30-06, 8x57mm, 338F, 358, and 35W.

Those cartridges have a max average SAAMI registration varying from 37k cup to 65kpsi.
So would the chrono be telling you you are exceeding the SAAMI limit or the case head limit?

Obviously, neither. Your technique is a fool's errand.

 

[Larry Elliott]

Clark, learn to read and comprehend plain English. When you've actually got some knowledge instead of what you've read somewhere we might "talk" again. Until then you can blather on all you'd like, I'm done with your terminal lack of understanding.

Go blow some primers.

 

[HangFireW8]

Larry,

I have some questions about learning about pressures from a chronograph.

Sometimes, as you note, a pressure excursion exhibits a non-incremental jump in velocity for an incremental increase in powder.

Other times, as you note, a pressure excursion exhibits a decrease in velocity with an incremental increase in powder.

I would add, that sometimes powder compression slows combustion propagation and that causes a flat spot, or even decrease in velocity, without a dangerous increase in pressure (or any increase at all).

What's more, I've seen, over my chronograph, normal incremental increases in velocity in the usual amounts, corresponding to incremental increases in powder, while pressures go through the roof. By through the roof, I'm not talking transitioning to flat primers, I'm talking about transitioning from rounded primers to a primer teat extruded into the firing pin hole, just by adding a several tenths.

So, the chronographed result of increased powder causing a pressure excursion can be normal velocity response, lack of response, markedly lower velocity, or markedly higher velocity.

One might say, you have to take into account other clues while watching the Chrono, but a statistician could tell you how large a data set it would take to sort out all the other clues to nail down what the chronograph is telling you about pressure. Think large, large, large data sets. And then, throw all that out and start over again when you switch powders.

I love my chronograph (a Shooting Chrony if anyone is curious). I shoot too many combinations of rifles, powders, cases, and bullets to derive any useful pressure information from it. Maybe if I was a one rifle/two powder shooter I could intuit more from the Chronograph. But in that case, I probably wouldn't have to.

-HF

 

[Larry Elliott]

The only times I've experienced velocities decreasing with increasing charge weights have been in handgun loads. Some of the older loads for rounds like the 9x19 required heavy powder compression if a full power load was wanted. Power Pistol took care of that problem though, and I permanently took care of the problem by unloading my last 9x19.

I've loaded rifle cartridges that required pretty heavy powder compression and the velocity increases weren't linear all the way to the top charges, but I wasn't going to fire 100 rounds for each increment to see. If all other pressure signs looked okay or even mild I didn't worry if the velocity increase was 1/2 of what it had been. The next charge increment frequently showed that the original velocity increase was back.

Some people indicate that the velocity will increase linearly all the way from starting to top charge. That's something I've hardly ever or never experienced. There are always blips in the data. If someone fired a LOT of rounds (50-100 minimum I imagine) per charge increment the data might smooth out some.

Looking for a good load for a .250-3000 (Rem 700 Classic), I tried RL-15 and found that it worked much better than any other powder I'd tried. Then I decided to try RL-19. More noise - ferocious muzzle blast, more recoil, but a lot less velocity. If I hadn't chronographed those loads I'd have never known that the RL-15 load was the best for velocity and accuracy.

If someone is loading for a rifle and getting velocity decreases with increased powder charges it's time to look for another powder IMHO.

 

[chino69]

Chronograph

I bought a chronograph when I just started to reload and learned quite a bit from its use. It can yield valuable info. during initial load development, variations in shot to shot velocity, etc. One important item I've learned is how to properly set up the sky shields after shooting my first chronograph. I didn't make the same mistake twice.

Today, I rarely use my chronograph. Most of the loads I shoot, I've already chronographed and developed other useful info. For someone just getting into handloading, I would definitely recommend one along with certain books and tools.

Lou Baccino