I have been pondering lately, what makes one load more accurate then another?

Say for example, the sweet spot the 270wsm I had was 63.4 grains of H4831sc, 140 NAB, F215GMM primer....

What is the reason/scientific or not behind the reason that say 63 or 64 grains, or a non GMM primer wouldn't shoot the same?

Why do most guns/barrels like or not like some certain powders? Example: My .257 wby shoots well with R25 but not R22 with the 100 grain bullets, and shoots better with H1000 then R25 on the 115 grain bullets.

Can anybody explain this to me?

Witchcraft

KC

It's democrat barrel maker schemes using different metal formulas to ensure they won't all like the same components. This ensures them that rich republicans will have to buy more and more gun barrels to shoot elite loads.

you can take 2 exact same factory models & sometimes one will get 3/4s in. at 100 & the other will only get 1&3/4s in.that is the reason one handloads--TO TAILOR THE LOAD TO EACH RIFLE THAT MAKES IT SHOOT THE BEST.---cranky72

There are various theories on causes of inaccuracy. Accuracy is found by eliminating the causes of inaccuracy.

Here is a link to some info (with some references linked there) you could look over for info on some of the theories:
Finding an accuracy node

Its magic.

The internet and key board jockeys.

+1

I am sure seating depth has an effect to some degree, but I have never seen a more dramatic effect than by changing powders or changing charge weight. The plot thickens...tell me why some guns of mine will shoot any load I try in them, and some of them only shoot one.

t hope you are not trying to apply logic to this quandry.---cranky72

I shoot benchrest, and have put 5 rounds into a 0.05" group at 100 yards. My friend Rick put 5 rounds through a 0.02" group with my old rifle that I gave him. Where accuracy comes from.

I would have to start with the right barrel because without a good one, there is nothing you can do. I have Bartlein, Shilen, Douglas, and Hart barrels on my guns. Premium barrels.

I would then pick a caliber that is inherently accurate and that you can get good bullets for. .22 cal, 6mm, 6.5mm, and .30 cal have been competition calibers and have excellent bullets available for them. I buy hand made bullets from Brady Knight, Bart Sauter, and Don Lahrs. J4 jackets and good quality control.

So, you have a premium barrel chambered for an inherently accurate cartridge. My 0,05" group was with a 6 ppc and a Bartlein barrel.

Next, the platform you are shooting from needs to be solid. Your barrel has to be bedded into a sturdy stock, and you've got to shoot off a heavy rest and a solid table. I can see my rifles rock left to right with my heart beat off a wood table, while a cement table will keep it steady.

Now, past the gun, you need to know what the wind is doing. I put out 3 Smiley Hensley wind flags for 100 yard shooting. I watch the flags and shoot when they are doing the same thing. You can squeeze off a round after the wind has shifted and mess up a real tight group.

If you have a good rifle in an accurate caliber with good bullets, you will close your group by shooting off a solid rest and watching the wind. I've seen lots of people shocked their guns shoot so well when I put reloads in it and let them shoot off my Farley rest.

I have a Rem 40X in .22L.R. that I shot with my buddy last Sunday at 100 yards. We get together and shoot the spinners. The wind was blowing 20 to 30 miles per hour and we were shooting .22s at 6" gopher targets at 100 yards. We're watching the wind flags and calling out 3" hold left. 4" hold left... We're hitting the things left and right. My rifle will shoot RBS .22 ammo under 1/4" at 100 yds and it is a blast to shoot with a 36 power scope at 100 yds. Accurate gun, good ammo, steady rest, and playing the wind.

Consistency, in all it's various forms.

RobP's post is a good one, but if you're really interested you might want to buy a copy of RIFLE ACCURACY FACTS, by Harold R. Vaughn. He's a scientist who analyzes accuracy as well as anyt source I've seen, though there are also some good books on benchrest rifles, loading and shooting. And they all apply to hunting rifles as well as target rifles.

However, some rifles I've owned have apparently been possessed by demons.

The saying is accuracy comes from the 4Bs; barrel, bullets, bedding and brass ...

From there, one heck of a lot of skill. The skill normally comes from practice and experience.

Blessings,

Steve

Yes, it is; and the magic that works one day will not necessarily (in fact, probably won't) work on another day.

You beat me to it.

A good friend that I shot the single shots with for years did an article for one of the Sierra load books that was titled: The Name of the Game is the Same. Meaning try to eliminate or get a handle on All variables and there are a bunch of them.

And in load development, work with a single variable at a time.

Blessings,

Steve

Steve once again speaks the truth! I know the biggest variable in the search for accuracy is me. When I am able to shoot a lot, groups shrink. When it has been a while, like it will be when I return from the sandbox and get to shoot again, I know my groups won't be so great.

I tried to be brief. If you've got the time... I spent a good 20 years reloading with a Rock Chucker and RCBS dies before I bought a benchrest gun. Lessons learned will benefit anyone.

I bought Lapua brass, a Sinclair case neck turner, Wilson tap dies, an arbor press, and some other stuff.
The rifle chamber is cut to a .262 neck diameter. The .220 Russian brass to be formed is turned down to .095" which will give you .010 neck clearance. This helps accuracy. Having a Minimum SAMMI spec neck and touching up hand loads with a neck turning tool will make your loads more accurate.

I had a .300 WSM built when the caliber first came out that was loose enough that you could take the firing pin and spring out of the gun, load a cartridge and shake the gun and hear the cartridge rattle. It had .05" clearance, which, although SAMMI spec, hurt the accuracy of the gun quite a bit. It shot 3" groups at 100 yds. I had to experiment with neck dies and sizing bushings and a concentricity gauge to get it down to about an inch.

Back to the bench gun. I fire form my .220 Russian brass to fit the 6 ppc. After that, I use the Wilson tap dies. I have 3 different diameter neck bushings to get the best fit on my bullets. I neck size until the rounds get stiff in the gun. I use a Redding bump (shoulder) die to set back the shoulder a thousandth measured by a RCBS headspace gauge. I also roll my finished rounds on a Sinclair concentricity gauge. I found a Wilson die out of whack and sent it back to them. Their customer service, to put it mildly, sucked eggs and it was 3 or 4 months of phone calls before I got a new die from them. I had to buy another one from Sinclair in the mean time.

It's important to accept the fact that dies aren't always good. What I found with a run out gauge is fairly common. Mike Rattigan a World champion bench rest shooter gave the advice to use a "float test" on questionable dies. Basically, you throw the die in the nearest body of water. If it floats, you keep on using it. Check your reloads.

Where do you seat your bullets. The benchrest standard starting point is 8 thousandths into the lands. You can fiddle with this and it may help. It's just like varying the amount of powder in the rounds. Another variable.

Nice bullets. The standard are bullets made with the venerable J4 jackets. It is actually preferred if you find a bullet that shoots to go and buy as many as you can from the same lot. Apparently there is variation from lot to lot in match grade jackets! Imagine what goes on with hunting bullets. Weigh a hundred and sort them. You might find them to be a grain over or under. You'll never know about the jackets unless you're getting solids. If I had the opportunity to get all my rounds from the same lots... I buy benchrest bullets by the thousand. That seems to be a good thing.

I could go on and on and on. You have to realize that all this and more is to win competitions decided by under a thousandth of an inch at a hundred yards. It seems far reaching but I remind myself that the military has always gone to competitive shooters for innovations and techniques to advance their own marksmanship.

RobP,

A couple of comments on your excellent post:

I did considerable bullet experimenting with a Juenke Internal Concentricity Comparator a few years ago. The ICC uses ultra-sound on a rolling bullet to measure how well the bullet is balanced, which has a LOT to do with accuracy. The machine absolutely predicted which bullets would tend to shoot better in any batch.

Once I proved how well the machine work, I tried measuring and weighing bullets to see if either technique could also pick out the "bad" bullets, instead of using a $700 machine. There wasn't any correlation. In fact, the bullets rated as most concentric by the Juenke machine (and shot very well) usually varied by a few tenths of a grain in weight, or had slight differences in diameter. My conclusion was that measuring or weighing bullets is pretty much a waste of time.

Unfortunately, the machine was on loan for a year and had to be returned. Since then Vern Juenke retired and no longer makes them. The only way to "sort" for accurate bullets I've found since then is to buy bullets with a reputation for accuracy--and even then, as you point out, even the best bullets will vary from lot to lot.

Your comments about dies are spot-on. Many handloaders have no clue about how good or bad their dies are, and without good dies you can't make good ammo. However, it isn't absllutely necessary to use hand dies. I have a 6mm PPC benchrest rifle and load the ammo on a Redding T7 turret press in Redding Competition dies. That combo produces rounds with no more than .00005 bullet run-out, and with the right loads the rifle averages 5 shots in the .1's at 100 yards.

I think that to answer the OP's original queastion, it comes down to barrel harmonics. All barrels are in essence, tuning forks. Just a little different vibration can send bullets in different directions. Or you can look at it like your garden hose spray nozzle. Just a little more or less pressure and water goes out in a wide pattern. But hit that sweet spot, and its one long solid column of water.

This is as good an answer as any other.

I used to think it was witchcraft, now I'm pretty sure it's voodoo........



Casey

I generally don't like smartazzes who pick apart words, etc.

But, technically speaking, precision and accuracy aren't exactly the same, although used fairly interchangeably in many writings. And we all know what the writer means.

"Precision" is the group size and repeatablity of that performance.

"Accuracy" is putting the bullet where it needs to go, "gun control" in the best sense of the term.

Nit picking...

DF

mathman thanks you!

That was my first inclination, too. Many of the things mentioned in a couple of detailed excellent posts here, more or less affect barrel vibrations. Handloading, all the other efforts notwithstanding, is about finding that magic formula that generates the most consistent and/or minimal vibration that permits repeatable accuracy.

But it's like everything else in life. If getting a rifle to group one inch takes X amount of time/dollars/practice, getting from there to under half inch groups generally will require exponentially increasing time/effort...and usually money!

Not necessarily.

In my experience, repeatable small groups are hardest to come by in rifles with stuff wrong with them that prevent small groups. That's because the barrel vibrates in various ways, due any number of factors.

In rifles that are put together right, small groups are pretty easy, and not much experimenting is necessary. They'll shoot about any good bullet with about any semi-appropriate powder.

That's why I suggested the Harold Vaughn book earlier in this thread. It's all about what causes accuracy, and it ain't magic or voodoo.

Many great comments.

I would like to add a few that seem to make a difference in what I have personally seen.

A good reamer with dimensions held to the tighter side of SAMMI specs with reduced neck release space and the right throat angle. I recently read that the 308 outshot the 30-06 when it first came out because the original 30-06's used a 2 1/2 degree throat where the 308 used a 1 1/2 degree. The author stated the steeper 30-06 throat angle was hard on the bullets influencing accuracy. Not sure where I read it or I'd link it.

A good crown. A crown that passes inspection with a borescope not one that looks good with the eyes will make a difference.

I agree with the other posters that every accuracy enhancement helps. Bedding, good trigger, quality barrel, good bullets etc.


Naturally every aspect of consistency in handloading plays its part. To answer your question, some powders just work better than others. Some loading books point out the most accurate powder.

Good thread.

One of the reasons I've published lists of "Loads That Work" is because certain loads do tend to work in good rifles of a certain chambering. And part of the reason I try such loads in any new-to-me rifle of that chambering is because if the load doesn't shoot well, then I know there's something wrong with the rifle.

I like accurate firearms as much as the next guy,...but there's a point that I won't allow my obsessive/compulsive nature to cross.

Madness lies on the other side.

Harmonics.

Lots of great information in this thread.

My experience with squeezing out the most from off the shelf mass produced rifles is below. Most have been good but we are at the mercy of the machinest/assemblers for barrel to action fit.

I would throw out for consideration that I do not crimp except for tube magazine rifles for the most part and I load off the Lands for hunting so that if I have to unload a loaded round, I do not pull the bullet and spill powder....

And while others may not agree with this, I find that the distance from ogive to rifling was one of the things that helped get rid of the occasional unexplained flyers. As I load, I measure with Hornady tool and make adjustments with seater die to make that distance to the lands consistent rather than the end to end distance or OAL. Edit Added: Each round is measured individually. I back off the seater and do a preliminary seating and measurement. Pain is the AZZ but so are flyers.

There are so many variables......And then when all else fails there is also witchcraft.

Seating depth is certainly one factor most handloaders don't consider.

But I would reiterate that the reason "harmonics" is usually given as the reason for accuracy is because the average rifle causes erratic harmonics. If we eliminate those problems, then rifles will shoot accurately with a variety of loads.

Maybe one way to calm down harmonics is to full length bed the rifle. It keeps everything as one unit as the barrel and stock become one in peace and harmony.
Jeez, I need more coffee. Sort of what Melvin Forbes theory is.

Accuracy Is a learned skill set of monotonous repetition administered with a firearm and load combination that is repetitious. And so forth. Or what Rob said.

I cause accuracy.



Travis

FINALLY we get the answer....

Despite my arrogance it is true.

Benchrest is akin to Formula 1. Most that equipment is equal, so it comes down to being the best driver on that day, or being the best shooter that day.

And if you get your head to wrapped up in it all, they still sell Budweiser.



Travis

As the resident rattle-shaker, whenever it gets into magic and witchcraft, I am obligated to weigh-in.

First off, forget witchcraft. That's just a bunch of overweight lesbians that like to dress goth. They can't shoot worth a poop.

Magic? Now, there you have something.

Look, I'm not all that great a shooter, and I don't own a true 1/2 MOA rifle. However, DogZapper got the first part of the thing right: a good foundation-- The 4 B's.

However, that is all just prelude. Somehow you have to do on the inside what you've managed to achieve on the outside. The rifle and the load have to be right, but far more importantly you have to be right.

For that, there needs to be a lack of "You" . Practice and repetition go a long way to achieving this, but basically you need to remove yourself from the process.

A good book for discussing this is Zen and the Art of Archery by Eugen Herrigel. It is a basic introduction to Zen. I'm not a big fan of Zen-- I'm much more of a Taoist by nature. You remember Chin, the Chinaman? He's a friend of Pooh. Chin is a first rate Taoist crank. Chin and I were talking one day and I was trying to get out of that old fart how it all works from his point of view.

Chin said, "It is like a monkey catapulting through the jungle:
Totally fascinated by the realm of the senses, it swings from one desire to the next, one conflict to the next, one self-centered idea to the next. If you threaten it, it actually fears for its life.

Let this monkey go.
Let the senses go. Let desires go.
Let conflicts go.
Let ideas go.
Let the fiction of life and death go.
Just remain in the center, watching.

And then forget that you are there."


That pretty much sums it up.

Spot on��������

I agree....a lot of load tuning is chasing after and trying to cure erratic rifles with problems.Like the tail wagging the dog.

Fix the rifle, or build it right,and loads will follow.The reason I don't go to the range with bunches of powders and bullets ready to do battle.

MD, I know you have a couple of quick tests you run on new dies, would you mind repeating those here? Thanks.

After addressing as many variables as possible, such as bedding, scope, jump, accuracy node loads, etc., icing the cake, at least to me, is checking and correcting concentricity.

Precision shooting is a multifacited excercise with many issues contributing to optimal performance. Just can't leave a link out of the chain...

DF

Bob,

You're right.

However, when a gun is less than optimal, sometimes one load will make it useable. I'm working on a .300 WM, Parker Hale Mauser for a good bud. I glassed it, free floated the barrel, recut the crown, plus every thing else I could think of. The barrel shows some wear thru the scope. I tried several loads without much success. The last load was 180 gr. NBT's over IMR 4831. It shot sub inch, first time ever. So, to save the barrel and make the gun servicable, he's going to stay with that load. It's a 2" gun with a tired barrel that seems to like this load. He'll shoot this combo until it quits, then it'll be time for a new tube.

DF

The above is why you hear guys state that if a rifle won't shoot a certain, proven load they have work to do. I agree with that in that if the rifle is built and or assembled properly it shouldn't take much load development or tweaking of a proven load to get it to shoot well. If it's being a PITA I send it to a trusted smith with targets of what is going on and give him an explanation of whats going on. Usually from there they know what to do to dissect the problem. I don't claim to be an expert but I can shoot well enough and have owned enough rifles to get me that far. Also if you ever worked on cars you will know that engines produce harmonics, potentially destructive ones and horse power robbing ones. That'swhy they have a harmonic balancer on them. However, like rifles, production quality has increased significantly to reduce or avoid this.

DF- yup.Sometimes we work with what we got...

A few years ago, I read an article about sleeving the barrel from receiver to muzzle. According to the article, this sleeving made a large improvement in accuracy.

I don't know the reason for the improvment, but a guess would be that the sleeving dampened the harmonics.
I don't remember where I read about it, nor if anyone else has had any experience with these barrels.

Seems like it would work something like the Browning and Winchester Boss.

smokepole,

The biggie is to test a resized case in a run-out gauge, the kind usually used to determine bullet alignment in loaded round. I test right behind the mouth of the case, and if the neck isn't concentric with the body within .003 consietently, then the die needs to be adjusted, or replaced if adjusting doesn't work.

Another test I only make on older dies is to check neck run-out on a case run into a full-length die with the expander ball/decapping assembly removed. The neck shouldn't have any more than .001 run-out. If it does, then there's no way to adjust the die to size brass correctly.

Back in the 1970's RCBS made quite a few dies by reaming the body and neck separately, and quite a few ended up with necks out of alignment with the case body. I had several of those at one time, and it took a while to figure out why they wouldn't make accurate ammo. One was a "custom" die for a wildcat, which cost quite a bit of money.

Testing using a piece of brass known to have a uniform neck is best, otherwise an innocent expander ball may get some undeserved blame.

I think JB has that covered, removing the expander ball to test the die.

You're right, the expander ball can be implicated when uneven neck thickness may be the main culprit.

DF

That's in the second part where he's checking older dies w/o the ball to see if the die body is bad.

In the first part he's checking how the die prepares a piece of brass for loading, and the ball is in place there.

Yeah, and NONE of y'all have mentioned the right sequence.

I do my best to 'squint' my eyes, 'grimace', & 'jerk' the trigger AT THE SAME TIME, every time. (consistently)

Works for me.








BTW - good info in this thread. THNX

What causes accuracy"

It is a little known scientific fact that accuracy results from the random clustering of bullets in close proximity. Other than this scientific explanation, I'd have to say, it's magic.

It is not magic, it is understanding and attention - in other words, the desire for accuracy produces the gumption to learn how to achieve it.

People who achieve accuracy understand accuracy.