How can a powder produce "Flyers"

[Boris_LA]

Along with amount of powder, and ability to ignite the powder, I would think variations in cartridge case volume would be a very big contributor. Much more significant that crimp.

Yes, but this can be reduced by using sorted brass of similar origin and age/usage. This will result a more consistent crimp as well.

[Roger Vick]

Slow burning powders usually require more powder, for the same velocity, than the faster burning powders.  That can result in compressed loads of powder, which means position changes of powder in relation to the primer don't happen.  The most accurate .308 and 30.06 loads I ever shot in my guns (M1A and 03A4) were compressed loads of IMR4350 over a Federal BR primer.

One thing about faster burning powders is that less powder makes more of a difference - so a small variation in powder charge (and maybe a small variation in ignition/burn rate) would make a bigger difference in bullet velocity, or so it seems to me.

How about the effects of uneven crimp with a fast burning powder?  A longer case may be crimped more than a shorter case??  More crimp should mean more neck tension and result in more pressure (increasing velocity??)  I don't trim pistol/revolver cases, but I do trim rifle cases.

Yes yes and yes, that opens up more cans of worms. My limited experience loading on a SDB 9mm mostly 124 gr 4.5 gr HP-38 seated at 1.155 works well the way I shot.

[Roger Vick]

Along with amount of powder, and ability to ignite the powder, I would think variations in cartridge case volume would be a very big contributor. Much more significant that crimp.

With all the variables to consider how is the powder HP-38 to blame so often for them pesky flyers. 

[Boris_LA]

I am looking on my testing logs/notes for 45ACP development. Tested 5 powders: HP-38, TG, Clays, BE, WST
The only one powder documented to have inconsistent groups with "flyers" across the testing range. You guest it - HP-38.
The format of the many group description shows 4+1, 8+2, etc... For example 4x0.8"+1=1.25" meaning that 4 shots were measured at 0.8" CTC and one opened it up to 1.25"

The rest of the powders produce even groups with different measurable sizes. All shots clearly belong to the same group.

[Roger Vick]

I am looking on my testing logs/notes for 45ACP development. Tested 5 powders: HP-38, TG, Clays, BE, WST
The only one powder documented to have inconsistent groups with "flyers" across the testing range. You guest it - HP-38.
The format of the many group description shows 4+1, 8+2, etc... For example 4x0.8"+1=1.25" meaning that 4 shots were measured at 0.8" CTC and one opened it up to 1.25"

The rest of the powders produce even groups with different measurable sizes. All shots clearly belong to the same group.

Your findings suggest HP-38 not as accurate as the other powders tested can not be ignored. I have much to learn and many powders to try, any suggestion for powder in 9mm loads for accuracy and consistency?

[Boris_LA]

I am relatively new reloader myself and only have experience with 9mm and 45ACP. More experienced reloading veterans usually recommend safer and easier powders to start. WSF and VV N320 are among them and I agree with this recommendation. Both provide very predictable and reliable starting point.

[Roger Vick]

I am relatively new reloader myself and only have experience with 9mm and 45ACP. More experienced reloading veterans usually recommend safer and easier powders to start. WSF and VV N320 are among them and I agree with this recommendation. Both provide very predictable and reliable starting point.

Thanks for the honesty, I have considered WSF and N320 among others. Time to do some testing, good thing I like to load and shoot 

[Boris_LA]

Good luck! The key is safety and very meticulous testing changing one variable at the time. Make a small sample, test. Change another variable, small sample, test. Repeat. It took me other 1K rounds before I committed to the first larger batch of a few hundred rounds.

Keep logs, notes pictures of targets and comments. I didn't expect to go to my old notes for loads that I don't use, but as you see they came handy now and reminded me why.

Long range ammo testing

[SoCal]

Some load data denotes which powder produced the most accurate results.  Of course that does not mean you will experence the same results with your gun and bullet and reloading methods but powder does make a difference.

[Boris_LA]

Those are just some marked samples made and tested for that session. All targets are marked with sample's recipe and collected for later analyzes. You can see different bullets and powders/charges tested.

[DeltaGray]

This was a great discussion!  I will not emphasize powder choice on this post but I notice self-inflicted flyers (and call them) during group testing from bag rest or done off-hand.  The word "Flyers" was in the subject and comments were made about rifles and powder. I thought of forum ID of MIA4ME as I mention (and repeat) that my 03A3 was once my pheasant rifle.  The original 1943 barrel with one FMJ surplus round punched a hole through the handsome pheasant and it was no longer a walker or "flyer". 

[M1A4ME]

This was a great discussion!  I will not emphasize powder choice on this post but I notice self-inflicted flyers (and call them) during group testing from bag rest or done off-hand.  The word "Flyers" was in the subject and comments were made about rifles and powder. I thought of forum ID of MIA4ME as I mention (and repeat) that my 03A3 was once my pheasant rifle.  The original 1943 barrel with one FMJ surplus round punched a hole through the handsome pheasant and it was no longer a walker or "flyer".

Now, I'm not sneaky enough to walk through the woods and shoot grouse with a rifle.  My dad and grandpa were.  In that case, they didn't have "flyers" either.  I'm one of those guys that needs a shot gun for grouse.

[DeltaGray]

I would not use a center fire rifle for flying pheasants, turkeys, quail or grouse; however, called and harvested turkeys with 7-08 scoped rifle.  Turkey hand loads were different from deer loads, steel or paper target loads.

[M1A4ME]

Talk of rifles reminded me of group issues I'd seen with new guys and rifles (iron sight or scopes) when they don't get a consistent cheek weld.

I just recently saw a new pistol shooter start off with his CZ 75 Compact grouping off the black to the left.  We discussed moving the rear sight but had not way to do it right then.  Good thing, too.  After a box or so of ammo his groups had moved to the center of the target.  I asked if he had changed his point of aim and he told me he had not.  He was still aiming at the center, the bullets "just moved."  He'd changed the way he aligned his eye to the sights.  Just like the rifle shooters do sometimes.

I would imagine it would be possible for someone to do that within a group when shooting a pistol, if they weren't really aware of it or were changing their grip (a pistol will move in your grip, like a rifle does if you're not properly set up with it).  It could look like "a flyer." 

Shot a round, or two, the pistol moves a little in your hand, not realized it, not correct it, the next round might not hit the same close area as the first two.

Once again, if you don't know what happened, why it happened, the pistol or the ammo might be blamed.

[DeltaGray]

At the range when a guy's new pistol throws a shotgun style pattern (or it misses the paper even at close range distance), I ask if that gun is for sale.  I should not try that bad gun with my loads because the guy wants to then keep it.  Grip must somehow be important.