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Old February 12, 2013, 04:12 AM   #1
bamaranger
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Join Date: October 9, 2009
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another Christmas chrono story!

Some of you may recall me posting earlier that my great pet .270 load using a 110 Sierra specifically for the purpose of solidly exceeding 3000 fps, when shot through my new Christmas chrony, was found to only be doing 2850!

As the prime weeks of deer season was not an ideal time to be load testing and developing, I put off working with the .270 and kept hunting.

But the season is now well over and I worked up some cases, dumped in more powder and ended up with 58g of IMR 4350 yielding an average of 3175. I can rest easy now knowing that I have a 3000 fps plus deer load.

While I was at it, I ran bamaboys and I's IDPA load of 5.1 gr of Unique and a 115 FMJ or Berry's plated through the screens, and got a very satisfying 1175avgerage for my pistol and 1125 for his, solidly within the power factors.

I have used my new chrono exactly twice now, and both brief episodes yielded valuable information, that I could not have obtained otherwise.

Guys, you need a chrono, and these days there pretty affordable!!!
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Old February 12, 2013, 05:55 AM   #2
Sevens
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I bought a chrono before the summer and have had some fun learning some things about my loads.

One thing I believed before, but now I am sure of is:
Quote:
Guys, you need a chrono
No way, no how. I didn't believe this before and now that I have one, I'm quite sure that I was right & still am.

It's a toy. It's also very much capable of drawing you to velocity that you truly had no genuine need for BEFORE you were able to measure it.

So I enter this post for anyone reading who doesn't believe they "need" a chrono. Know what? You are absolutely correct.

If you want one -- you should get one. If you don't think you need one, I'll back you up on that. You truly don't.
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Old February 12, 2013, 09:02 AM   #3
serf 'rett
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I'm kinda a "group hug" handloader instead of a "speed freak"; not that I oppose a group that does have some gallop.

Don't own a chronograph (yet), but got the chance to clock some 9pm handloads through a freind's gizmo about a month ago. Discovered:

The walk-in-park loads, that I was sure were below IDPA power factor, were in fact - below power factor.
The loads I thought to make power factor, did so.
The Urah, chest thumping, full bore, manly man loads were arriving on target in less time - like in about 250 fps less time than the midrange loads.
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Old February 12, 2013, 09:39 AM   #4
Mike Irwin
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A Christmas chrono story?

"You'll measure the velocity at which you put your eye out, kid!"
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Old February 12, 2013, 01:49 PM   #5
Sevens
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Quote:
The Urah, chest thumping, full bore, manly man loads were arriving on target in less time - like in about 250 fps less time than the midrange loads.
That sounds interesting. Got any working theories? Same or different slug? Same or different powder?

One of these deals where velocity drops after reaching it's peak or something else at work here?
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Old February 12, 2013, 02:28 PM   #6
snuffy
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IF all you want is to see how fast any given load is going, then no, you don't need a chrono.

If you want to know everything you can about those loads, then you do need one.

You take a manual specific load, match the components as good as you can. BUT the velocities are all over the place, along with terrible groups, you have something wrong with your loading practices. It could be as simple as mixed headstamp brass. Or a powder charger that is dropping inconsistent charges. Or-or-or a bunch of other things. CONSISTENCY is the name of the game for a lot of things, but handloading it is of most importance. A chrono will tell you that.

Now you're loading for a high powered rifle, a classic bottlenecked case. You want to drive a premium bonded bullet at the highest velocity you can. Shooting over a chrono will tell you when any given powder is running into it's highest working pressure. Loading rounds that increase the powder charge the same increment as you work up the load, you will see the gain in velocity for each higher powder charge start to fall off. More pressure, but not more velocity. If you push it even higher, the velocity can actually go DOWN-decrease! How would you know that without a chrono?

Knowing the velocity of a rifle bullet will allow you to calculate downrange bullet drop. Along with the ballistic coefficient , the calculation can be figured. Using the book value, or what they claim it SHOULD be may be all wrong. You may have a "slow barrel". Like my Ruger .280. A 140 grain ballistic tip was supposed to be going 2950 fps. Over my chrono, it was actually 2650!

It killed deer DRT at close ranges of under 100 yards, but a long shot of 350+ missed low. Good rest, relaxed, should have hit him. That's when I actually checked the velocity.
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Old February 12, 2013, 02:34 PM   #7
Sevens
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Quote:
If you want to know everything you can about those loads, then you do need one.
I don't agree.

You can learn a bunch about your loads with a chrono.

You'll never, ever, ever learn "everything you can about those loads" with a chrono. You need better & more expensive equipment to pull that off.

If you want a chrono, get a chrono.
If you think you need a chrono -- get a chrono!
If you don't believe you need a chrono... you are correct. You don't need a chrono.

EDIT: Snuffy's got great info and examples in his post. I don't mean to discount any of what he said -- I can't argue a bit with it, because it's all valid. I'm merely trying to make the point that FOR YEARS, I've seen folks in handloading forums try to tell other folks that they "need" a chrono and they aren't serious about this without one and some even suggest that it's haphazard or dangerous to continue to handload without owning and using one, and that drives me up a wall. It's a tool, like a comparator or a concentricity gauge. It's a useful item, but it's not a must-have.
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