Chrono ?s

A

ADIDAS69

New member
Thinking of picking up a Magnetospeed this month. How important is it really to chrony your rounds so you're not using more powder than needed to accelerate the bullet? If a person were to make sure to use the exact same charge in every cartridge does it really make a difference having extra powder?

Thoughts?
 
Chronograph results will save components during load development because you're getting data that would otherwise require more shooting.

Take a load you're wanting to test. Load one each from you're starting charge to where you expect to max out. Shoot them watching for pressure signs while also recording velocity. Let's say you have charge weights in 0.30gr intervals from 40.00 to 42.40. 41.5 and 41.8 show somewhat of a flat spot in velocity while charges below and above that have large changes in velocity. Somewhere around that 41.5 / 41.8 where you need to look for your load.

Now you have some more test loads in the 41.5 / 41.8 range. Shoot for groups, record velocities and standard deviation among charge weights. Still not done? Then fine tune seating depth, primers, minor tweaks of charge over the chronograph looking for better groups, but also reduction in SD.
 
Chronographs will show more than just how much powder to use.
Checking velocity is also a way to help determine pressure.
Like when experimenting with bullet depth in the case, for example.
 
I use chronograph strictly as a means to measure velocity and from there I can calculate energy and trajectory. I could care less if I'm dropping an extra grain of powder per charge than I need (so long as there is no safety issues caused by doing so), there's 7000 of those babies in a pound and I usually lose a couple while clearing my powder measure anyway. what I do care about is most load data companies fudging their data by using the longest barrels possible and slowest burning powders possible so real world loads end up several hundred FPS slower than the published data. my favorite was Hornady using a 32 inch test barrel for a cartridge that most people test with a 20 inch barrel so that their load data ended up looking 600 FPS better than the nearest competitor.
 
Bushy tails and big ears

I suppose i should have realized i was in a rabbit hole when i ordered my Meplat trimmer. I all of a sudden feel like Pinocchio when he realizes he's got donkey ears. Magnetospeed ordered.

tahunua001: as a matter of total coincidence i am using a 26" .308 diameter barrel (30-06) with a 1/10 twist and Nosler 190s. Nosler publishes data using what i am guessing is my rifle as their barrel definition is the same. I will be pleased to see if the data matches real world.

A couple of you mentioned bullet depth. I was told once (and never pursued further investigation) that I should seat the bullet as high as the magazine and/or chamber would allow. The assumption* i am guessing is that this would create a seal more quickly and also reduce marring of the bullet surface as it exits the shell casing.

*"You assumted!? Well don't you do no more god damn assumting!"
 
I got a chronograph a couple years ago and it's been a great tool for giving me data about my loads. I have found though that since I'm shooting outside depending on where the sun is does have a relationship to what my reading are. In your case using the Magneto one you should not have that issue.
 
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adidas,
personal experience with noodler is that they are pretty accurate if you meet their criteria precisely but they usually go with 24-26 inch barrel lengths, even when dealing with calibers that are overwhelmingly shot from 16 inch barrels(like 7.62x39mm and 6.5 grendel). if you have a 26 inch barrel you are probably going to see pretty good results.

as for seating bullets as far out as possible, it has to do with the jump the bullet has to make upon leaving the casing before it engages the rifling. you want that jump to be as short as possible to prevent unnecessary throat erosion, and increase bullet stability.
 
Is the Magnetospeed the one that straps onto the end of the barrel??

If it is, wouldn't that change the harmonics of the barrel (aka effect it's accuracy)???
 
Have a PACT model one from the 90'a...

and I use it for all reloading. [Shotguns are a hoot!]

But for pistol try to zero in on recoil for duplicating carry ammo.

Keeping the ES [Extreme Spread] to minimum seems to confirms best accuracy.
 
Is the Magnetospeed the one that straps onto the end of the barrel??

If it is, wouldn't that change the harmonics of the barrel (aka effect it's accuracy)???

Yes,It straps onto the barrel. No,It doesn't affect accuracy,but it will change the point of impact a little.About like installing a suppressor on a rifle,the POI will change a little,but the groups will remain pretty much the same.
I absolutely love my Magnetospeed V3. The speeds are a little different than a standard style screen chronograph.Being that it records the actual muzzle speed,it will show faster fps speeds than a chronograph that is placed 15-20 ft in front of the muzzle.
I've not had any problems with my ballistics data and shooting dope using the V3's data shooting long range.It has been as reliable as any other chronographs that I've used.
 
It's like trying to drive a car without a speedometer. You can do it, but you'll eventually get into trouble unless you always drive like grandma and shoot mouse fart loads.

I have no desire to load my ammo "HOT", but at the same time if I own a 30-06, I don't want to shoot 300 Savage loads in it I want to be able to at least match listed speeds for factory ammo.

The velocities you see posted in manuals are just a rough guide. You can be exactly half way between starting loads and a listed max load and still be well over pressure. Or you could be 200 fps slower than expected. With a chronograph you know how fast you are and will know BEFORE you get over pressure. Normally used pressure signs that people try to use don't show up until you are WAAAY over.

Unless you know the true speeds you are getting all of the online ballistic calculators are pretty useless too.
 
Reloading with a longer overall length can also minimize the risk of high pressures to some degree.
As long the rounds slide up and down freely in the magazine and feed properly, of course.
 
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