How close is close enough?

[Mikecr]

All the jackets used in making a batch of bullets don't get shaped to identical dimenions in the final stage of manufacture where the front part's sized to a point

This is ogive radius variance, and yes it does affect our measurement datums. D.ID, unless you qualified your ogives for radius first, further measurements were meaningless.

All the bottleneck cases headspacing on their shoulders don't have the same head-to-shoulder dimension

Mine do. I know because I verify every one.

All bottleneck cases headspacing on their shoulders have their shoulder set back a thousandth or so by firing pin impact; that changes the bullet's jump-to-rifling distance when the round fires.

You'd have a hard time proving this, and end up with qualifiers to the contention, I'm sure. While lower shoulder angle cartridges might exhibit some wedging on firing, higher shoulder angle cartridges do not. My headspace holds, that is, measures same before & after, on primer firing with 223Rem, 6BR norma, 6XC, and 6.5wssm.

When all these variables add up, they'll make the bullet's jump to the rifling vary a few to several thousandths.

You sound defeated. But I assure it is very possible to make ammo to exact dimensions, with no generalizations needed for it. I also think you'll be hard pressed to prove that doing so is a bad approach in reloading.

The only way anyone (in my opinion) will get zero spread in bullet jump distance is to use a light neck tension on bullets then seat 'em out far enough to be pushed back into the case neck when chambered and fired. Regardless of all the other tolerances in places mentioned earlier, this method eliminates all of them.

I highly doubt the lands would produce more accurate seating than a Wilson seater plug.

Too bad there's no bullet seating die for rimless bottleneck cases that uses the case shoulder as a reference instead of the case head. That would remove one of the variables.

This is managed by setting headspace to exactly the same values. Nothing new there.

Folks, reducing variables in reloading is much of what it's about.
If you produce high runout, you can generalize it away as not mattering, or you can determine the causes & fix it.
Same with variances in headspace, seating, every sizing, capacity, charging, etc.
And while shortcut sloppy ammo may shoot well enough for you, it doesn't hurt a thing to make it as good as you can.
It helps me, because when I'm wondering about getting more from a gun, removing errant shots, lowering ES, better load development, etc, I hold a far smaller list of variables to consider.

I had a gun I thought should have shot better. It was barely 1/2moa, yet my ammo was perfect for sure & I believed my load was perfect. It had to be the gun itself. Weeks of chasing a very tough intermittent problem led to concluding that it's NF NXS scope had an internal issue. NF tested it, found a lens issue, fixed it, and the gun finally went to shooting 1/4moa solid. Without confidence in my ammo, I could have chased this one forever.

I had another gun throw shots a bit here & there. Again, I knew it was not MY ammo.
Turned out to be a slipping firing pin set screw..

So I say it's best to scratch as many variables off the list that you can -right up front.
If you believe seating is an uncontrolled variable as Bart suggests, well, at least you can get it right on the bench. This much I know.

 

[D.ID]

I sort bullets and brass first but have found some bullets to be less symmetrical than others at the ogive. That is all I meant. Of course we should be aiming for 0 discrepancies but if our components are not perfect loading to perfection with those components is by definition impossible.

 

[Bart B]

If anyone reloading ammo to zero tolerances (or as close as humanly possible) in every dimensional and mass aspect and get 20 shots in a group better than the one below I get with reloading ammo to the tolerances I mentioned earlier, then so be it.

 

[D.ID]

Why aint you got that group framed?

 

[Joe King]

this is ogive radius variance, and yes it does affect our measurement datums. D.id, unless you qualified your ogives for radius first, further measurements were meaningless.

Mine do. I know because i verify every one.


You'd have a hard time proving this, and end up with qualifiers to the contention, i'm sure. While lower shoulder angle cartridges might exhibit some wedging on firing, higher shoulder angle cartridges do not. My headspace holds, that is, measures same before & after, on primer firing with 223rem, 6br norma, 6xc, and 6.5wssm.

You sound defeated. But i assure it is very possible to make ammo to exact dimensions, with no generalizations needed for it. I also think you'll be hard pressed to prove that doing so is a bad approach in reloading.

I highly doubt the lands would produce more accurate seating than a wilson seater plug.

This is managed by setting headspace to exactly the same values. Nothing new there.

Folks, reducing variables in reloading is much of what it's about.
If you produce high runout, you can generalize it away as not mattering, or you can determine the causes & fix it.
Same with variances in headspace, seating, every sizing, capacity, charging, etc.
And while shortcut sloppy ammo may shoot well enough for you, it doesn't hurt a thing to make it as good as you can.
It helps me, because when i'm wondering about getting more from a gun, removing errant shots, lowering es, better load development, etc, i hold a far smaller list of variables to consider.

I had a gun i thought should have shot better. It was barely 1/2moa, yet my ammo was perfect for sure & i believed my load was perfect. It had to be the gun itself. Weeks of chasing a very tough intermittent problem led to concluding that it's nf nxs scope had an internal issue. Nf tested it, found a lens issue, fixed it, and the gun finally went to shooting 1/4moa solid. Without confidence in my ammo, i could have chased this one forever.

I had another gun throw shots a bit here & there. Again, i knew it was not my ammo.
Turned out to be a slipping firing pin set screw..

So i say it's best to scratch as many variables off the list that you can -right up front.
If you believe seating is an uncontrolled variable as bart suggests, well, at least you can get it right on the bench. This much i know.

+1000

 

[Joe King]

I sort bullets and brass first but have found some bullets to be less symmetrical than others at the ogive. That is all I meant. Of course we should be aiming for 0 discrepancies but if our components are not perfect loading to perfection with those components is by definition impossible.

yup your right but that's point! to strive for better

 

[Bart B]

Why aint you got that group framed?

'Cause there's nothing special about it. Folks have been doing that well at long range since Sierra Bullets started making hollow point match bullets. Using proper full length sizing dies correctly on fired cases then seating bullets atop powder charges to the tolerances I mentioned earlier. 'Tain't rocket science. Just basic stuff.

 

[D.ID]

Oh hell, I know it. I just never save em unless I'm framin em. I do not think I have ever fired a twenty round group. I'm just to cheap to send that much ammo threw the same piece of paper......................Duke

 

[Mikecr]

Given that pretty much any basic reloader here assembles ammo as well as Bart, I'm somewhat motivated to believe we all shoot wallet groups -all the time.

The problem is, this doesn't really appear to be the case.
I personally have to put some effort into my ammo, including load development, to get guns shooting to their potential. And so it's somewhat 'special' to me when I manage it.
It also appears to me that by far most final results in both F-Class, and 1k IBS, blush to the .4MOA pic posted. So apparently not all folks are doing so well at LR as Bart.

But maybe we should just BELIEVE we are despite..............

 

[Bart B]

It also appears to me that by far most final results in both F-Class, and 1k IBS, blush to the .4MOA pic posted. So apparently not all folks are doing so well at LR as Bart.

Get out on the range at 5 AM, set up and shoot at 5:30 while the sun's still well below the horizon. Your test groups will be shot in air still enough to see, with a decent spotting scope, bullet holes in the black a long, long ways away. As the sun gets closer to being visible over the horizon, the air often starts moving a little bit and drags bullets in flight with it.

Others with similarly loaded ammo I've mentioned have been out at that time of day at similar ranges shooting .2 MOA and smaller 10-shot test groups.

 

[chucknbach]

Get out on the range at 5 AM, set up and shoot at 5:30 while the sun's still well below the horizon. Your test groups will be shot in air still enough to see, with a decent spotting scope, bullet holes in the black a long, long ways away. As the sun gets closer to being visible over the horizon, the air often starts moving a little bit and drags bullets in flight with it.

Others with similarly loaded ammo I've mentioned have been out at that time of day at similar ranges shooting .2 MOA and smaller 10-shot test groups.

I agree. Conditions like that are what you want to take as much of the variables out as possible. Competitions don't always have ideal conditions.