Smallest group or smallest SD?

[Dthomas3523]

I’m not well edjumikated so this stats stuff is way over my head.

What I can say from my experience is if I get a decent SD/ES on ten shots and the load a above and below it closely show a similar pattern or even better minimal speed differences as well and I run with it I’ve yet to get burned by that load and I can comfortably load it without having to be within a kernel of powder or any other crap.

leap of faith based on a small observation?
Maybe,,,,but it’s working for me.

Many are still loading circa 1995 where you load to the book OAL or a random .010 or .020 jump and then tailor the load to that. Which is why you see people shooting groups with powder charge increments.

Instead of picking a charge based on velocity nodes and then adjusting the seating depth to that node.

 

[Gustav7]

I absolutely only started using chrony data for load development when I got my magnetospeed.
My older chrony was not trustworthy and I strictly observed vertical then.

I still think it has a place, I just don't trust it as much, ESPECIALLY if i'm doing multi shot strings and looking at ES. The velocity itself seems to be somewhat accurate, but I just get wild outliers consistently.

I'm just starting load development for my Savage in 6.5cm. What I did is two 10 shot Satterlee ladder tests, but basically going to shoot them at distance as well. So Going to shoot one 10 shot string through the chrony on target at 500yds, same POA. Then go mark and check, and repeat that process in reverse. Hopefully match some velocites up with vertical string groups as well.

We'll see how that goes

 

[Dthomas3523]

I still think it has a place, I just don't trust it as much, ESPECIALLY if i'm doing multi shot strings and looking at ES. The velocity itself seems to be somewhat accurate, but I just get wild outliers consistently.

I'm just starting load development for my Savage in 6.5cm. What I did is two 10 shot Satterlee ladder tests, but basically going to shoot them at distance as well. So Going to shoot one 10 shot string through the chrony on target at 500yds, same POA. Then go mark and check, and repeat that process in reverse. Hopefully match some velocites up with vertical string groups as well.

We'll see how that goes

The “wild outliers” aren’t wild at all. And outliers is exactly what you want to account for. The chrono isn’t lying to you (as long as a qualify chrono).

Those outliers become much smaller if you up your brass prep and QC methods.

It’s a sliding scale:

The better your prep and QC: the smaller shot strings required to get reliable data and the smaller your ES and such is.

The less prep and QC: the larger number of shots you need for reliable data and the higher your ES will be.

Those groups don’t mean anything if at anytime you might send a round that has a 40 fps difference.

 

[Gustav7]

The “wild outliers” aren’t wild at all. And outliers is exactly what you want to account for. The chrono isn’t lying to you (as long as a qualify chrono).

Those outliers become much smaller if you up your brass prep and QC methods.

It’s a sliding scale:

The better your prep and QC: the smaller shot strings required to get reliable data and the smaller your ES and such is.

The less prep and QC: the larger number of shots you need for reliable data and the higher your ES will be.

Those groups don’t mean anything if at anytime you might send a round that has a 40 fps difference.

Yes I understand that, I'm not new to reloading. I'm not trying to cover up poor reloading with "bad chrono"... and I did mention that I have a $100 pro chrono, so I doubt its as reliable as a magnetospeed.

What Im talking about is good brass prep and solid reloading technique....no I'm not a benchrester but confident in my reloading ability. Then I shoot a string of 5 shots at 400yds through my chrono. I get an ES of around 15ish, and a 3-4in group at 400yds. I do this across 3-4 strings, and the group downrange stays the same but then my chrono shows one shot with 100fps difference. My group downrange stays solid with no increased vertical, but my ES is now 120.... to me, I just don't see how that couldn't be the chrono.

I'm not trying to blame anything on the chrono, but I don't have another explanation for it. Input is always welcome

 

[Dthomas3523]

Yes I understand that, I'm not new to reloading. I'm not trying to cover up poor reloading with "bad chrono"... and I did mention that I have a $100 pro chrono, so I doubt its as reliable as a magnetospeed.

What Im talking about is good brass prep and solid reloading technique....no I'm not a benchrester but confident in my reloading ability. Then I shoot a string of 5 shots at 400yds through my chrono. I get an ES of around 15ish, and a 3-4in group at 400yds. I do this across 3-4 strings, and the group downrange stays the same but then my chrono shows one shot with 100fps difference. My group downrange stays solid with no increased vertical, but my ES is now 120.... to me, I just don't see how that couldn't be the chrono.

I'm not trying to blame anything on the chrono, but I don't have another explanation for it. Input is always welcome

Ah. $100 chrono. No bueno. I definitely agree with you there.

 

[Gustav7]

Ah. $100 chrono. No bueno. I definitely agree with you there.

lol yaaa thats why I try to do load development at distance as well. With the satterlee ladder I'm just doing it twice, see if I can get a repeat node on paper at 500yds

 

[Billiam1211]

When it comes to lowering ES/SD, what do you all think is most important other than weighing accurate charges? Brass prep? Seems like neck tension and concentricity are popular subjects.

 

[Steel head]

Brass prep is a and finding a stable node.

 

[Dthomas3523]

When it comes to lowering ES/SD, what do you all think is most important other than weighing accurate charges? Brass prep? Seems like neck tension and concentricity are popular subjects.

Brass prep brass prep brass prep

Concentricity is a QC check on brass prep. If your concentricity is off, there’s an error in your prep.

Neck tension is usually more associated with group size and such. Unless you have way too much or way too little.

 

[Gustav7]

When it comes to lowering ES/SD, what do you all think is most important other than weighing accurate charges? Brass prep? Seems like neck tension and concentricity are popular subjects.

Ya I'd say good brass prep (and consistent brass prep), finding that good node will naturally help es/sd. I think neck tension and bullet seating gotta be up there. I don't have any actual data, but I feel like inconsistent neck tension would effect pressure/velocity as much as minor powder charge changes. Anyone comment on that?

 

[Dthomas3523]

Ya I'd say good brass prep (and consistent brass prep), finding that good node will naturally help es/sd. I think neck tension and bullet seating gotta be up there. I don't have any actual data, but I feel like inconsistent neck tension would effect pressure/velocity as much as minor powder charge changes. Anyone comment on that?

Let me rephrase, consistent neck tension is important. I include that in “brass prep.”

Experimenting with different tension is for group size.