Just Bought a Chrony Now What?

[Autorotate19]

I just bought a Chrony alpha today and I am wanting to develop loads for two rifles here soon with it. I understand extreme spread and standard deviation but could you explain to me how you would go about developing a load from scratch in the quickest most efficient way.

The first one is a 300wsm with 150gr barnes ttsx, hodgdon H4350, norma brass. This is not really a super long range load, just to about 600 yards.

The other one is 6.5-285, 140gr berger, not real sure on powder whatever gives me the best velocity, lapua brass. This is a long range load for out to 1,000 yards.

Any help or suggestions appreciated!

 

[rscott5028]

The Audette ladder test is a popular and effective method.

There are many variations. The biggest problem I see is folks trying to work with too many variables. Start with quality components that others have enjoyed success with and perform the tests while you change one thing at a time.

Here's one explanation: Long-Range Load Development

In my opinion, you can do your load development just fine without the chrony. Groups don't lie. But, knowing your muzzle velocity will improve your chances when shooting any distance/condition when coupled with the right ballistics software.

-- richard

 

[bigngreen]

Make sure you mount it solid, they are kinda whispy. I shoot mine prone a lot with it securely to a solid base low to the ground. Also make sure you don't get your wires in the hinges !
I do all my load development over the crony, it saves me more components and time over having to group shoot every load at long range to see how they shake out.

 

[Autorotate19]

How many rounds should I shoot to get a good sample on extreme spread? 3, 5, or 10 shots? Thanks for all the responses!

 

[garfield]

How many rounds should I shoot to get a good sample on extreme spread? 3, 5, or 10 shots? Thanks for all the responses!

somes thread talked for it...mayber with the search engine...

but, i believs is 14 rounds for good statistics

sorry, i NOT statistician so...i don't why..

 

[rscott5028]

You can structure all kinds of statistical models and analyze it to death.

If you want a strong estimate of the ES for a 5 shot string, then you need to shoot a 5 shot string and record the ES. Do that 30 times and take the mean/standard deviation of the ES of each of the 30 samples.

But, you don't have to go to those extremes to get useful info.

more data is always better
but, it helps if you are able to correlate cause and effect
keep good records and look for patterns

clean vs fouled barrel
1st 1 or 2 shots may be slower
brass prep
powder
weather

If you're tuning for competition, you're interested in the consistency for a given number of shots fired within some time limit.

If you're gearing up for hunting, you're more interested in that first cold bore shot.

Don't over-think it.

 

[Autorotate19]

I thought I read somewhere that first you shoot 5 shots for every powder increment until you find an acceptable extreme spread. Once you find that shoot groups with it, adjusting seating depth until groups shrink. Does this sound right?

 

[rscott5028]

I thought I read somewhere that first you shoot 5 shots for every powder increment until you find an acceptable extreme spread. Once you find that shoot groups with it, adjusting seating depth until groups shrink. Does this sound right?

That sounds like a variation of the ladder test to me.

I think you can be successful in any number of ways. But most importantly, you need to have a method and record your results so that you can measure progress.

If you hunt and peck at random, or change too many variables at once, you may never find the right load.

JMO
-- richard

 

[garfield]

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/EnglemanChronographStatistics.pdf

fyio

 

[rscott5028]

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/EnglemanChronographStatistics.pdf

fyio

good paper

He needs to write one on chi square and regression analyisis to help determine how much each variable influences group size. (temp, pressure, powder, bullet, seating depth, number of rounds fired between cleaning, cleaning methods, throat errosion, ad infinitum...)

But like he points out, you may not have any barrel life left by the time you sufficiently estimate anything with a high degree of statistical confidence.

 

[joe0121]

First I look for the load I see posted most often online. For example lots of people see great results in the .300 wm wit 76 gr of h1000 and a berger 210gr vld bullet .010 off the lands or rammed in the lands.

So i set my powder measured as exactly as my scale can (+/- 1gr which is about the norm)

I work back 5 gr and load five rounds of each: with the pill .010 off the lands

70
71
72
73
74
75
75.2
75.5
75.7
76
76.1
76.2

Obviously the first light loads wont produce good accuracy or velocity but they heat up the bore and give me a chance to get into the groove. Pick the best three groups than experiment with bullet seating.

this should get you pretty **** close within a hundred rounds. beyond that with magnum calibers you shoot your tube out before you finish your testing.


also read the manuals and what people use on the forums to give you starting places.

YMMV I have been reloading for exactly three months, and this is my variation on what others have done.

worry about cold bore vs warm bore later once you have a load.