Velocity and accuracy and SD

dan158

New member
How many mark the shot (1 thru 5 )and then record the velocity after each shot also..
If so does this help at all when working up loads with other powders to get a better sd number?

If ones gun is shooting very well at 3720 to 3728 But it starts to open up the groups at below 3720 and above 3728.

Does one want to find a powder that can spit the bullet out more consistent at those speeds between 3720 and 3728.. And is it possible to get SD numbers in single digit?

Just trying to understand how to get a better SD on loads to be more consistent.

Thanks all. Dan
 
part of the SD game is matching a good combo of powder/primer/bullet along with brass prep and loading techniques. things like consistent neck tension, consistent powder charge, good primers and even going the extra mile and deburring the flash holes all come into play. Temp can also effect that for some powders as well.


a lot of what you'll need to do to get there will depend on what you're making the rounds up for.

are you trying to find something to punch the smallest possible groups on paper? or are you looking for a good hunting load that will carry velocity out a couple hundred yards and MOA or a little better is acceptable?

what caliber are you trying to load for - folks might be able to give you some advice on good combinations to work around.





i dont log POI for each shot, but i do log all my chrono data (and atmospheric data) to add to the master data base i'm compiling for my guns. my spreadsheet has a bunch of green lines across it with my pet loads that shoot the best. and not all of them are the bestest SD numbers, but many coincide with it.

as a hunter i generally i look for a load that 1) shoots good and 2) has ok SD numbers. if i can get both, in that order - i'm happy and load away - even if the ES/SD numbers arent the best on that peticular powder/primer/bullet combo.
 
Plant.One pretty much covered it all.

There are a lot of variables to control to get to a single digit but to answer your question, yes. Is it always the same single digit? Not that I've been able to achieve.

I guess what it boils down to is at what point will the effort go beyond the point diminishing returns for you?
 
Most long range shooters are annal about powder charge, as in one grainule of powder. They are also concerned about their neck tension being as consistent as possible. In fact, they will try to get all the cases as much alike as possible, weight and capacity. All this to get as low SD's as possible, so they get less vertical stringing at long range.

Chronographs lie. Changing light, and some other things, will screw with them. My Oehler has three sensors, as in two traps, so that it reads each bullet twice. It rarely gets the same number on both. Long strings of fire on different days, rarely give the same numbers. If your getting SD's in single digits, your lucky, or your chrono is lying to you.
 
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I just ordered one of the magneto V3 chronos and will be trying it out next week.. I hope it gives a more accurate reading across the board.. I have one of those corny rcbs bullet/spaceship chrono..
I am reloading for 204 and my groups are very good coming from my AR at 100.. I am loading the Winchester and Hornady up with cci magnum primers, H4895 and topping them off with 40 gr Noslers..

Thanks all.. Dan
 
They need to be aligned properly and set firmly. Adjust your sensitivity. There's a narrow window of magnetic field that registers. But, once that's done, you'll be good to go. I've found them to be very repeatable, unlike the optical type.
 
i love my magnetospeed - no light to fuss with, and i can use it at ranges that dont allow traditional chrono's to be setup.


my only complaint is the data format (.csv) that it saves it in. its not linear, so you have to do some hokey pokey to get from what it gives you to a regular single line format for a standard spreadsheet .
 
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