Chrono or no chrono??

[Salmon-boy]

When working up loads with CBs, should one have a chronograph?

Would the answer be different for Rifle or Pistol loads?

[pdawg_shooter]

I have had a Pact crono for about 8 years now. Used the hell out of it at first, now just used it maybe one or two times a year. Accuracy is way more important to me.

[VTDW]

Even a cheapie chrono is a must if you push the envelope on velocities IMHO. If you are experienced you can certainly get by just fine without one. Last weekend I had my buddy bring his chrony to the range because I was trying for max velocity with a new boolit powder combo and the loads were compressed. I achieved velocities well over the written load data and the chrony proved it. Was I nervous?...heck yes!! It's a guy thing. There were no signs of excessive pressure, but still, it was nice to have a chrony there to make sure as it was uncharted waters for me. As usual I found some outstanding accuracy below max load data.

Dave

[Bass Ackward]

If you are pushing, use a chrono cause you can't develop velocity without building pressure.

If you are going to shoot cast like cast, and use the start low and work up method, it's not a necessity.

[Maven]

Very nice to have when you're working with some milsurp powders, e.g., IMR 5010, IMR 7383. Also good to have when you're trying to develop a load with a plain-based CB, e.g., the Lee 30-150-TL-PB and wondering why there's lots of leading, but little accuracy.

[mike in co]

if you are going to do load development, why would you leave a primary tool off the list ?

yes you can "reload" without one, but if you strife to be an "ammo crafter", buy a decent one.

[Larry Gibson]

I suggest the use of a chronograph always when developing loads. This is especially the case if loads are tested at ranges less than 50 yards. Also if the loads are going to be shot past 50 yards. Accuracy, especially at short range, does not tell you consistancy. A load than is accurate and consistant at short range will also be accurate (given a correct bullet) at longer ranges. I've seen a lot of loads with large extreme spreads of velocity were very accurate at short range but really inaccurate at medium or long range. I suggest the use of a chronograph. Doesn't hurt any thing but it will provide additional information that is useful.

Larry Gibson

[HABCAN]

Larry, I have a question for you. (I have a PACT.) I know we all try for minimal readings of SD and ES, but I would appreciate your opinion on what is 'too much'.

[beagle]

If you're shooting "stock" loads out of a reloading manual and stay within the parameters with listed bullets you probably won't need one.

If you do any shooting that uses components outside the loads listed in manuals, you definitely need one. There is very little data listed for H & G, Saeco, RCBS, Lee and some of the later Lyman bullets. Very little data listed for milsurp powders and no pressure readings. Almost no seating depths. All of these things affect the velocity...and pressure of a load.

A chrony won't give you pressure readings but it will tell you velocities which are directly tied to pressure. I fear that many of us get away with murder using cast bullets as they're much more forgiving pressurewise than the jacketed variety.

Get a chrony, use it and use your head and record your results meticulously. You'll be miles ahead if you do./beagle

[Larry Gibson]

Larry, I have a question for you. (I have a PACT.) I know we all try for minimal readings of SD and ES, but I would appreciate your opinion on what is 'too much'.

When deveoping loads (5 shot groups) for rifles I look for an ES less than 30 fps with a SD of 30-40% of the ES.

To confirm a load I will shoot 2-5 10 shot strings or two 20 shot strings looking for an ES of 50 fps or less with the attendant SD of 3-40% of the ES. Most often my confirmed loads have an ES less than 25 FPS over a 10 shot string.

Since I shoot at longer ranges I pay more attention to the ES and then look to see if the SD falls in the correct range. Many only quote the SD with thier loads but I've seen some pretty small SDs with large ESs. To quote Dr. Ken Oehler; "you should consider standard deviation; don't worship standard deviation."

Larry Gibson

[218bee]

As a reloading nut I feel it is a must have. I do not load to maximum to see where velocity/pressure spike each other but as a hunter and long range shooter knowing the velocity in "MY GUN" is information I want instead of guessing what velocity I am at.

[xtimberman]

I felt like I had operated successfully without a chronograph for decades, and now I can't imagine how I did it!

Seriously, a chrono saves me a whole lot of time when working up loads - particularly when developing loads for auto pistols that function within a narrow power range. I usually like to target a specific velocity range first, then tweak COAL, charge weight, etc. to fine-tune accuracy and function. With a good library of load data and a chronograph, I can often find the desired velocity quickly without wasting too much time and too many bullets.

A chronograph removes a lot of the guessing when working on the safe maximum end of a load combination. You can quit long before you get to the cratered primers and head separations.

xtm

[runfiverun]

sooner or later the chrono is going to come out!

just because the "book says" don't make it so.

[standles]

I find my chrono invaluable in my tinkering with loads for cast and the Jword.

I don't kow how I ever got along without one.

Steven

[joeb33050]

When deveoping loads (5 shot groups) for rifles I look for an ES less than 30 fps with a SD of 30-40% of the ES.

To confirm a load I will shoot 2-5 10 shot strings or two 20 shot strings looking for an ES of 50 fps or less with the attendant SD of 3-40% of the ES. Most often my confirmed loads have an ES less than 25 FPS over a 10 shot string.

Since I shoot at longer ranges I pay more attention to the ES and then look to see if the SD falls in the correct range. Many only quote the SD with thier loads but I've seen some pretty small SDs with large ESs. To quote Dr. Ken Oehler; "you should consider standard deviation; don't worship standard deviation."

Larry Gibson

We need a lot of MVs measured with a chronograph, probably 30 or more, to know much about the true MV and SD.
ES or extreme spread is mathematically linked to Sd or standard deviation. If you know one, you can calculate the other. SD is a "better" measure of variation.
While the chronograph is handy with near-max loads, and with unknown or surplus powder, and while many claim that the chronograph is crucial for load development, I have NEVER found a shooter who could or would explain how the chronograph helps in accurate load development with known powders. NEVER. And I've asked.
See the CBA nationals results, see the majority of ESTIMATED MVs.
joe b.

[Whitespider]

My vote goes for the chronograph. Virtually every shot fired off my bench is over sky screens. But my shootin' range is in my back yard, makes it easy for me.

[felix]

Chronos are fun! But, only after the load is developed. The only ES I measure is the spread at the target. The velocity ES would be much more important for when the target is GOING to be beyond the point of normal interest. ... felix

[Larry Gibson]

We need a lot of MVs measured with a chronograph, probably 30 or more, to know much about the true MV and SD.
ES or extreme spread is mathematically linked to Sd or standard deviation. If you know one, you can calculate the other. SD is a "better" measure of variation.
While the chronograph is handy with near-max loads, and with unknown or surplus powder, and while many claim that the chronograph is crucial for load development, I have NEVER found a shooter who could or would explain how the chronograph helps in accurate load development with known powders. NEVER. And I've asked.
See the CBA nationals results, see the majority of ESTIMATED MVs.
joe b.

You never asked me.

The answer is simple; with the chronograph you know the consistancy of the load which holes in paper do not show nor tell you. Granted repeated shooting of a load will tell you if it is consistant (what some the bench resters do) but with the chronograph you know with one test. I have shot some pretty good groups at shorter ranges with some pretty inconsistant loads (ES's well over 200 fps). At longer ranges the inaccuracies of such loads is readily apparent. With the chronograph such loads are eliminated in the development stage with no further effort or waste of componants spent on them. You also know the MV and can then accurately calculate the trajectory and sight adjustments without guessing or time/resource consuming tests. For hunting the chronograph tells you if your loads are within the parameters you want for proper terminal effects. I've seen 200-300 fps +/- difference between chronographed velocities and published velocities including cast bullet velocities. The use of the chronograph has cut my load development time down considerable as I get excellent loads quickly without having to experiment with many so-so loads in between.

Also while SD is a measure of uniformity for a long range shooter ES is more important. You don't know what the velocity of each round is as you must go with the Average. SD only tells you that a certain percentage (the larger the number of rounds tested the greater the %) of the shots in the test will fall within the SD +/_ of the average "mean" velocity. With a 10 shot string this means that 7-8 of the shots fall within the SD fps of the mean velocity. What about the other two shots? (they are outside the SD fps figure) With a 3 or 5 shot test the SD is even less meaningful. With the shorter shot strings the ES and SD are certainly good indicators and can be used to judge whether a load has merit for further development but a small SD with a 3-5 shot group is pretty much meaningless if taken by itself. I've seen numerous loads with small SDs but a larger than expected ES as one round was a considerable fps apart from the others. With such a load that round will go out the bottom (if a much lower velocity) or out the top (if a much higher velocity). This means a miss or crippled game if hunting or loss of points if in a match. It may very well just be frustrating if plinking. The problem with such a load is you never know when that odd round is in the chamber. I'd rather have a consistant load which is why I look for the smaller ES and the comparative SD percentage wise. As Dr. Oehler mentions, I don't worship SD. BTW; I've been chronographing loads since '75 so my experience with them is extensive.

Larry Gibson

[jhalcott]

Yes, a chrono is needed to be certain of the velocities you are getting. It will also tell you when you are getting the most from your powder charge. When you get LESS increase in FPS from a standard increase in charge weight, you know you are at or near the upper limits of that load. I normally work up to an accurate load THEN use the chrono. I may tweek the load at that point.

[S.R.Custom]

... Accuracy is way more important to me.

Same here. I've got a fair amount of gear, but never bought a chrono. I've always worked up loads for accuracy and paid strict attention to pressure signs. In that context, the velocity is what it is... There's enough published load data out there with velocity figures that you can compare your loads to to it and get a fair idea of what's going on. The exact number has never been that important to me.

That said, the only time I've used a chrono was when I was building my 7mm Mag long range rifle with the 30" barrel. I was dying to know how fast those 175 gr slugs were coming out of that long of a pipe (3035 fps). And even then, it was just a matter of curiosity. The SD (11) merely repeated what I already knew from punching the paper.