Causes of flyers?

[Swamp Fox]

Not necessarily a cast boolit question, but I’ve been working up some loads for a rifle. I’ve got a few acceptable loads, and one that seems great, except for the occasional flyer. The rifle generally will shoot around 2” groups, but one load I’ve tried will give 3 holes touching then a couple random rounds 4” away. Everything else seems good, all loaded to with in a couple thousandths of the same length, very consistent velocity.

What causes the flyers?
Is it just barrel harmonics with a particular load that a rifle doesn’t like? Seating depth? Is there a place to start with fine tuning it to make a good load or should I just move on?

[Winger Ed.]

After the normal precautions--
Maybe weigh out the batch of bullets, and be sure the barrel's crown is good/polished.

[challenger_i]

After following Ed's advice...

Assuming you sort your brass to the same weight, head stamp, trim length and, hopefully, lot number, I would recommend annealing your cases and try the loads again.

[Shopdog]

Hmmm, there's a reason quality barrels cost what they do. So if you're pushing a factory barrel,especially one with a sporter profile, much past 3 shots.... well, as much as it pains my frugality to say it,you get what you pay for.

Are there some factory barrels that can be outstanding,of course. What is,or are your chances of getting one? I'd say one in a hundred on varmint profiles and maybe half that for thinner profiles.

On cast; how well,and how efficient(quickly) you can make effective changes in your process "should" allow you to keep ahead of the curve. Meaning,if you're stuck with say one sizer die.... one top punch.... one mould... You see where this is going?

The ability to experiment plays a tremendous role in the search for accuracy. Seating depth is critical IME. Seating *"straight" is right there with that. Annealing then becomes part of the conversation. Powder burn rates,and a bunch of other fun things to try.

*Seating straight; cast is grippy,real grippy. So make darn sure the boolit is as straight as possible, before it hits the seating die. They don't self correct like a harder JB. This same effect shows up in the chamber. Where a jacketed bullet will get right with the bore centerline,cast if presented to the leade in the chamber is misaligned... well,it just isn't gonna get any better. Nope,it's going to get worse.

So,seating on the press... and seating in the chamber are two areas that leave something "on the table".

You need to have fun. If it becomes that 4 letter word.... WORK.... Well,you're in for a rough ride. The very best of luck with your shooting.

[dverna]

Hmmm, there's a reason quality barrels cost what they do. So if you're pushing a factory barrel,especially one with a sporter profile, much past 3 shots.... well, as much as it pains my frugality to say it,you get what you pay for.

Are there some factory barrels that can be outstanding,of course. What is,or are your chances of getting one? I'd say one in a hundred on varmint profiles and maybe half that for thinner profiles.

This is easy to check but boring.

Fire 2-3 shots and wait 10 minutes for the barrel to cool.

[fenderman57]

Had that trouble with a 223 and ball powder, switched to a magnum primer and that cured it.

[waksupi]

If cast bullets with conventional lube, I would guess lube purging. If jacketed bullets, check diameters with a micrometer. Clean copper fouling from the bore.
If those aren't the problem, there is nothing wrong with the barrel, it is a bedding issue.

[oldleadhead]

If all else being equal perhaps it's the technique of the person driving. Look for variables there, especially "breathing"...

[Larry Gibson]

Not necessarily a cast boolit question, but I’ve been working up some loads for a rifle. I’ve got a few acceptable loads, and one that seems great, except for the occasional flyer. The rifle generally will shoot around 2” groups, but one load I’ve tried will give 3 holes touching then a couple random rounds 4” away. Everything else seems good, all loaded to with in a couple thousandths of the same length, very consistent velocity.

What causes the flyers?
Is it just barrel harmonics with a particular load that a rifle doesn’t like? Seating depth? Is there a place to start with fine tuning it to make a good load or should I just move on?

If you've got "acceptable loads, and one that seems great" there's nothing wrong with the rifle that needs correcting. As for the "occasional flyer" with those loads if not caused by you then it's probably caused by a defect in the bullet. Solution is to properly weight sort the bullets. I've posted how to do properly weight sorting so you may find it using the search function.

As to the "one load I’ve tried will give 3 holes touching then a couple random rounds 4” away". That obviously is just a bad load. It's most likely caused by inconsistant ignition and burn of the powder used or the bullet is being pushed too hard/fast. Since you haven't told us the cartridge used, the rifle used, or any specifics about the load or cast bullet used it's difficult to guess which is the problem. More detailed information would be helpful?

[MostlyLeverGuns]

It is probably not the barrel. It is surprising how ugly a barrel can look thru a bore scope and still shoot very well. Like waksupi said, bedding is probably the problem. Getting the barrel clean, really, really clean before load development helps a lot. Sometimes just changing powders without cleaning can cause poor grouping. Many older ball/spherical powders leave a hard residue in the barrel if not cleaned after shooting(Bl-c2,others). Changing bullet type cast, jacketed, PC can cause accuracy issues. STRAIGHT cartridges make a big difference.

[Kraschenbirn]

Not really sufficient info provided by the OP. Rifle? Caliber? Barrel length/profile? Specific boolit info? Load data...like powder, charge weight, primer, etc?

So far as a barrel problem...once upon a time, I owned a pre-64 M70 'Featherweight' in .270 Win (I'd [probably read too much Jack O'Conner in those days.) that would put the first three rounds under a half-dollar then began to wander as the barrel heated up. Tried everything we could think of: trigger job, bedded the receiver, floated the barrel, diddled with different powders and bullet designs to no avail. Finally just gave up and settled for what it was...a darned effective coyote killer. The point being that, sometimes, you just got to accept what is and live with it.

Bill

[Gewehr-Guy]

I have examined a lot of my bullets that were shot into large snow piles used as backstops. Some have revealed voids in the sides of the castings, even after examining them before sizing. I think they could be the cause of a random flyer, so now all my bullets are weighed.