What Causes Horizontal Dispersion When Testing Loads

[22BRGUY]

What works for me is to first focus on vertical with powder charge and then focus on horizontal with seating depth and then go back to powder charge to fine tune a bit more
Best Wishes

 

[Jet]

Tyler

Above info is all very good but verticle can also be caused by other factors. You mention in your first post that proper equipment and shooitng technique are present. My commets address these since wind has been covered. Also, LHSmith discussed doing everything the same from shot to shot. This is critical. Shooting small on occasion can be done by many who are new to precision shooting. Shooting small consistently takes mastering all aspects of the process. Cleaning, brass prep, loading, bullet prep, bench or position set up, your fundamentals when handling the rifle, etc all influence how you and the rifle shoot.

Here are just a few other areas to consider:

- How are you measuring powder weight/how much variance do you have between charge weights?
- Do you anneal your brass?
- Front and rear bag use. Type of bag, bag sand, style designed for your stock, etc all are part of tunning.
- Do you shoot free recoil or holding the rifle. Are you consistent from shot to shot?
- If shooting from a bench is it solid, if prone are you loading te bipod?

Consistency is key. Enjoy the journey towards precision and good shooting.

Rich

 

[Tyler4565]

What role do wind flags play when testing loads then? I understand that when shooting, wind flags tell you where to hold off, but how do you use them when trying to establish a load? Or do you guys only test loads in zero wind?

 

[hogpatrol]

My horizontal stringing usually lessens after a couple brewskis. ;D

 

[LHSmith]

What role do wind flags play when testing loads then? I understand that when shooting, wind flags tell you where to hold off, but how do you use them when trying to establish a load? Or do you guys only test loads in zero wind?

Best way I can answer is it puts all the loads on a level playing field......where bullet dispersion from wind drift is not a factor in group size. FWIW, when testing I don't hold off....I let the group form where the condition takes it ( Remember-shooting as close to same condition as possible), this eliminates any error in judgement by retaining a distinct target bull for precise aiming.Re-read my posts or better yet get either of the following books - "The Book of Rifle Accuracy" by Tony Boyer or "Extreme Rifle Accuracy" by Mike Ratigan about the importance of testing in various conditions. Buy the book(s) ,take notes, then sell it on here....if you are serious about learning accuracy....it will be the best money you ever spent.
Since you are still puzzled as to how much wind flags help, you may not realize wind is often unidirectional, at many match venues it is common to see all 4 flags ( typical for a 100 yd match , 1 near the bench, 1 @ 25, 50, and 75 yds) periodically show different directions with different velocities or a flag or two do an instantaneous 180 flip (known as a reverse). Imagine holding off for a right push and a reverse comes as you pull the trigger. Now you can see where the shot will be off twice as far as the what the drift tables values. Without flags you would have no clue what happened and most likely blame the load.

 

[Tom Thomson]

Tyler
In my limited experience, there is a difference between horizontal stringing and horizontal dispersion. Dispersion - most likely wind; stringing - most likely sights/gun.
tommyt

 

[BCBRAD]

A friend pointed out to me when asked about horizontal stringing is that I had not adjusted the parallax out of the scope for the distance I was shooting. Once corrected, groups improved .

 

[jim_k]

I've seen this even when shooting indoors, with two loads, both the same bullet, case, OAL, but 0.4 gr different powder charge, and got 0.9" lateral spread (5 shot groups) with one load, and 0.34" round group with the other load. Same day, same session, same shooter. All shots called good.

 

[Lapua40X]

Let's' not forget the shooter's influence on the shot.

Butt placement inconsistency at the shoulder; inconsistent shoulder pressure; degree of pressure in the hold on the grip; finger position on the trigger; position and attitude of the butt stock on the rear bag (if used); canting of the rifle.
None of these are load or weather related. Always check the shooter first ....

 

[Mozella]

;...............snip.......... Without flags you are just guessing ......snip.........

I would argue that WITH flags you're still guessing. Otherwise they would call my sport "F-Class X Ring Demonstration" rather than F-Class Competition.

Reading flags beyond 300 yards would be problematic for obvious reasons. All successful short range BR competitors in the last 35 years have used flags. SR BR = 100 - 300 yds, F-Class 300 - 1200 yds.

You missed my point. We use flags in F-Class too, they're just fewer and a lot larger than the ones used in short range BR which are sometimes so numerous they look like someone is planting a garden of radishes. Wind flags are invaluable in competition; no argument there.

But my response is to the idea that you can do accurate load development in the wind by reading the wind flags. Well, perhaps there are a few folks who can, but if it was all that easy, manufacturers of firearms and ammunition wouldn't build those expensive testing tunnels.

I would argue that the average person reading this forum in search for advice (or those here who are giving advice) are kidding themselves if they believe they can evaluate a significant wind accurately enough to do quality load development on windy days.

Yes, there are those who budget 15 rounds for load development, shoot a small 3 shot group, and use that as their eureka moment as they claim they found the perfect recipe. That's not likely to be the path to Nirvana.

When you're picking the fly sh**t out of the pepper, you're searching for tiny differences in performance, often measured in a few thousandths of an inch. Testing different brands of primer or determining if sorting Lapua cases by weight is really worth it requires a very careful test set-up as well as precise target evaluation in order to produce truly scientific results. Measuring group size with a carpenters tape is not going to do the job. The last thing you need is an additional factor thrown in which is not only nearly impossible to measure accurately, it's constantly changing, second-by-second, during the testing session.

Ask any competitor who shoots a match in windy conditions, like I did just yesterday. One guy had a mechanical malfunction as a valid excuse, but nobody else mentioned having the wrong scope, the wrong charge weight, the wrong primer, or anything else related to equipment or tuning. We all explained our less-than-600 scores by talking about the changing wind and our inability to judge it accurately enough to put all our rounds in the X ring in spite of the fact that every shooter there had a rifle fully capable of hitting the X ring nearly every time along with the shooting skill to do so except for one thing........... the wind.

BR shooters talk about relative humidity, barometric pressure, and the amount of sunshine hitting their barrel on windless days. But when the wind pipes up, they too talk about almost nothing except the wind when explaining why they didn't shoot a world's record.

 

[LHSmith]

Flags explain those "mysterious" flyers that occur in almost every group. Learning how to use them saves time, money and barrel life. Was it the load or the wind? - Flags narrow the culprit down pretty quick.
FWIW -many a shortrange BR record has fallen while shot in some nasty conditions. Those that know how their rifle/ load combo performs in all conditions gathers the most points....to them it's a been there/ done that deal aka "Confidence"