Why Short Range Load Testing Doesn't Work

[Lapua40X]

There was a recent post asking about a good "distance to target" standard for testing loads. I was at the range today, testing loads only for MV so the "spread" wasn't important, using short distance targets.
The 6BR MV test loads for the target pictured here ranged from 26.5 to 28.6 gr of Varget; a total of 18 rounds. Just wanted to offer this example for new shooters who are having problems understanding why their load tests at short ranges make their work more difficult and why they should should get out to longer ranges for better data. A click on the image will give you a better view.
Oh... I should mention that the photo isn't inverted, the target was posted upside down at the range. But the message remains the same.

Sorry, I neglected to list the range as 100 yards (thanks for the heads-up Hopkins)

 

[Hopkins]

Just for clarification,at what range was the target?

 

[DRNewcomb]

If I ever get to the point that I'm putting 18 rounds through a single hole at 100 yds, I'll be sure to remember this thread. ;D

 

[Raythemanroe]

I agree 100%, I did the same thing at 2 hundred with a group! out of five one was out of the group in my ladder test. It's 3 hundred minimum. then when you find a node move back further and fine tune it more!

 

[Steve Blair]

At what range and in what discipline do you compete?

 

[Raythemanroe]

18 rnds does seem exceptional for ladder testing with different powder charges! Most guys mark there rounds at the target not to get them confused.

 

[savageshooter86]

What kind of #s did you get over the chrony?

 

[Phil3]

I guess I am in trouble since there is no range around here past 200 yards. - Phil

 

[Immike]

That's a really short ladder test you have there. Are them bullets tumbling ? That looks like a keyhole, lol.

 

[Lapua40X]

At what range and in what discipline do you compete?

Up until now I've only competed in 300 yard squirrel shoots. Just a local club thing. Been practicing trying to acquire competency at 600 - 700 yards and beyond but I don't have a rifle of my own that will handle the wind out that far. Hoping to build a .284 sometime late in the year that will do this:
http://forum.snipershide.com/snipers-hide-reloading-depot/64907-***-284-win-loads***.html

 

[Lapua40X]

What kind of #s did you get over the chrony?

Spread ranged from 2463 to 2775. My ballistics calculator indicated I might expect a 1/4 MOA variation and that's about what I got on this windless sunny day. Hence the importance of putting more distance between shooter and target.

 

[Lapua40X]

I guess I am in trouble since there is no range around here past 200 yards. - Phil

Doesn't Chabot Gun Club or Livermore-Pleasanton Rod/Gun Club have anything over 200 yards? It's a bit of a drive (perhaps hour and a half) to Sacramento Valley Shooting Center (http://sacvalley.org/) from where you live but it'd be worth the drive.

 

[Erik Cortina]

Lapua40X, why doesn't short load testing work?

 

[M14AMU]

Hmmm....I figured Erik's wrench was gonna get 'torqued' by this post! ;D :

 

[Erik Cortina]

Hmmm....I figured Erik's wrench was gonna get 'torqued' by this post! ;D :

ROFL! Well, maybe I'll learn something!

 

[Lapua40X]

Lapua40X, why doesn't short load testing work?

Well, let's see if I can explain my theory regarding short "range" load testing.
Let's theorize that our load is a 107 gr .243 HPBT bullet with a BC of .527 and our first series of loads average 2400 fps. We shoot our first group and follow that with another set that averages 2500 fps which, ballistically, should be expected to group about .5 MOA above the first group at 200 yards. But at 300 yards the difference should be about 1.7 MOA. A third test averaging about 2600 fps should print about 3 MOA higher than the previous set at 300 yards. Point is that the further out your target is set the greater spread differential you'll get from one test series to the next, making it (IMO) easier to understand the results of your work. Finding a node inside a series of very tight groups is virtually impossible. The closer you position your target with respect to the muzzle of the rifle and tighter group you can expect and the more difficult it is to distinguish the value of one load from another.

 

[Erik Cortina]

Lapua40X, why doesn't short load testing work?

Let's theorize...

I think I found the problem. ;D

Anyway, it's late and I'm going to get some much needed rest. Happy shooting and may all your groups be one hole.

 

[savagedasher]

I have a little something that is over looked. first you need to test your load at 50, 100,150,200,and500 yds with tight paper and see if it cuts a clean hole. Billy Stevens taught me that while shooting bench rest. Good Shooting Larry

 

[Dgd6mm]

Good point Larry. I don't know about Billy's long game, but he builds excellant & accurate short and longrange benchrest rifles.

 

[Beau]

There was a recent post asking about a good "distance to target" standard for testing loads.

You were using the wrong test for that distance. A better way for short range is to watch MV & ES for each load. You have to shoot more than one shot for each load.