School me on compressed loads and Standard Deviation

[44hunter45]

I've been handloading since 1986. I make beautiful, functional, consistent hunting ammo. I can hit sub-MOA when I pay attention, but it is not target/match quality ammo.
When I was younger it was all about velocity and I stuffed powder in the case until I got pressure. I made a lot of compressed loads.

As I got older, I chose powders that put me at my pressure at a high density, but not compressed. My theory is that variations in individual case volumes are exaggerated as a load nears 100%.
Leaving enough headroom for the variances means fewer fliers. Meaning that even if I weigh all my cases and they are exactly the same. I weigh all my bullets and they are exactly the same. There will still be some loads that fill with powder before others.

Here is the question for you guys that are making single digit SD ammo. Does any of that matter? Is load density that big a factor? Can you achieve small SDs with compressed loads?

Or is it all about super consistent neck tension?

How are you getting super small SDs?

 

[Chingon]

I recommend listening to the Hornady podcast - they have several episodes that dive into what matters and what doesn't, and why what you think you observe may not be solid info.

I get 10 round sub-0.6 MOA groups with double digit SD's. What matters more?

 

[N2TRKYS]

I recommend listening to the Hornady podcast - they have several episodes that dive into what matters and what doesn't, and why what you think you observe may not be solid info.

I get 10 round sub-0.6 MOA groups with double digit SD's. What matters more?

View attachment 337139

What your velocity?

 

[Chingon]

2640-ish with my 18" barrel + suppressor. Hits 1800fps at 800yds at 5,000' elevation.

 

[N2TRKYS]

2640-ish with my 18" barrel + suppressor. Hits 1800fps at 800yds at 5,000' elevation.

10-4. My Tikka has a 24” barrel and has 143 grain eld-x going 2750 fps. My 142 grain ABLR loads are going 2800 fps. I hope I get to shoot something with these loads this year.

 

[Wind Gypsy]

Fill ratio is WAY over considered by lots of people. I don’t like heavily compressed loads and don’t use powders so fast that they have very low fill ratios. Beyond that, fill ratio is a non consideration.

 

[Sheltowee]

I recommend listening to the Hornady podcast - they have several episodes that dive into what matters and what doesn't, and why what you think you observe may not be solid info.

I get 10 round sub-0.6 MOA groups with double digit SD's. What matters more?

View attachment 337139

Mmmm... H4350 and the 6.5 Creedmoor. I've got down just under .4MOA with my Tikka CTR and SMKs.

 

[std7mag]

Single digit SD isn't the end all, be all.
As @Chingon said, what does your target tell you?

When I first started loading, I'll admit, I was worried about too much pressure. So my loads were very low.
And kicked like a son of a gun!
Turns out too low, and you get unwanted pressure spikes.

Then I heard about compressed loads.
So I tried that.
Ends up I was using too slow burning powder and my charges were too compressed.
Was bad enough that the bullet was pushing out of the neck, making it too long to chamber.

Now, I look for 85% fill on the low side. And no more than 104% on the high side.

 

[44hunter45]

Single digit SD isn't the end all, be all.
As @Chingon said, what does your target tell you?

When I first started loading, I'll admit, I was worried about too much pressure. So my loads were very low.
And kicked like a son of a gun!
Turns out too low, and you get unwanted pressure spikes.

Then I heard about compressed loads.
So I tried that.
Ends up I was using too slow burning powder and my charges were too compressed.
Was bad enough that the bullet was pushing out of the neck, making it too long to chamber.

Now, I look for 85% fill on the low side. And no more than 104% on the high side.

See, that's what I'm talking about. My perfect load is around 95% density. For Hammers I look for powders which give me start loads with around 85% because they will always ladder "over book". Meaning they will take a higher charge than any other bullet of the same weight. I'm still aiming for around 95% at pressure.

I learned pretty early I could make a cheap A$$ed Speer BT shoot 1/2 MOA if I jammed it into the lands. So just saying "Look at my groups" isn't everything either. I can still remember being in my late twenties and having to leave the field because I had a 180 Speer BT stuck in the throat and a magazine full of powder. That pull-through in your pack is worth jack when that happens. I was making flamethrower compressed loads of IMR 4831. One shot in the evening and you were blind for a while from the muzzle flash.

I think 1/2 MOA isn't nearly the challenge today that it was 40 years ago. Bullets are better, powders are better, rifles are better, shooters understand rifling twist better. A 10 round group at .6 MOA does impress me, I must say. Those are fine loads and some fine shooting.

 

[44hunter45]

I just realized I posted a very similar thread two years ago. I got the same answers. HT is sure consistent!

 

[p_ham]

ES and SD matter more the farther out you shoot. My 1000 yd loads I like an ES of 20 or less. For hunting loads, I like to keep ES 50 or less, the farthest I'm willing to shoot at fur is 400 yds.

Load density, I try to be somewhere in the 85%-104% range, with at least .01" jump to the lands.

I don't try too hard to make a certain combo shoot well. You can usually tell during pressure ladders if that combo is going to play ball or not. If it's not, change powder or bullet.

 

[cahunter805]

+1 p_ham! The ES does matter further out. Brass prep and load density does play into ES also. Neck tension is one of the big factors as well.
All that said I like 20 or under if I can find the node but I don’t stress to much on it.