Does Berger Make Jump Irrelevant?

[Phil Rizzo]

Agreed there are multiple peaks and valleys, going in the same direction with seating changes.
With Berger hybrids they occur around about .030" apart or close, in my experience.

 

[MagnumManiac]

Tell me if my math is wrong. A very mild cartridge eats lands at the rate of 0.003 per 100 rounds. A barrel burner eats that in 20 rounds. That's more than 0.01 in 100 rounds for a barrel burner like say 264 WM. I can't see how chasing 0.003 inch seating depth adjustments makes sense.

Please tell me where I'm wrong?

How Fast Does A Barrel Erode?

A match-grade barrel is a big investment for many shooters, so how much life you can expect from it...

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Those in the know, don't chase the lands, this is futile and silly.
What we do is, take velocity readings AFTER measuring the erosion of the lands distance, then add powder until the previous velocity is reached and this is why our BARREL TIME stays the same. It is not the distance to the rifling that governs the sweet spot, it is BARREL TIME HARMONICS that governs where the bullet exits in the barrel whip…

Too much emphasis is used on LAND DISTANCE, it really means little when you have multiple distances that will tune the same. This is why a barrel tuner works, it changes harmonics to match the barrel time, not the distance to the rifling is even necessary to know.

Cheers.

 

[Straight Shooter]

I have my own Weatherby reamers in 300/340/375 Weatherby, all have .500" of freebore just how Roy Weatherby designed them before they were submitted to SAAMI, the only list of these original proprietary specs are held by CIP. 378 Weatherby was .750" and 460 Weatherby was 1.00" freebore when developed.
Seating depth tuning is not governed by distance to lands, it is the harmonics of the bullets BARREL TIME that is changing with seating in or out.
There are many seating lengths that will be apparent when tested within a magazine length restriction, often being .020"-.030" wide.
Even .100" off the rifling can be just as accurate as .010" off.

Cheers.

^^^^^^^ I like this. I didn't know this.

 

[fruitnut]

What happens to barrel harmonics when you develop a load at 90F in summer and then going hunting in winter at 20F? Velocity drops, barrel time changes, load is out of whack. So, I guess we have several loads at various charge weights? One for each temperature?

 

[Phil Rizzo]

Rule number one:
Use a temperature stable powder. Even if it costs you some velocity.

There are plenty variables you can't get a grip on.
Lock down the ones you can.

 

[hemiford]

Those in the know, don't chase the lands, this is futile and silly.
What we do is, take velocity readings AFTER measuring the erosion of the lands distance, then add powder until the previous velocity is reached and this is why our BARREL TIME stays the same. It is not the distance to the rifling that governs the sweet spot, it is BARREL TIME HARMONICS that governs where the bullet exits in the barrel whip…

Too much emphasis is used on LAND DISTANCE, it really means little when you have multiple distances that will tune the same. This is why a barrel tuner works, it changes harmonics to match the barrel time, not the distance to the rifling is even necessary to know.

Cheers.

Thank you.
I've never seen this in words before.
So playing with seating depth near the lands has the same objective of chasing consistency of small groups,
with the added danger of overpressure if you get too close to touching ?
Wanting to seat into the lands, then, has no intrinsic benefit by itself ?

 

[Duffman]

I love this discussion. How much time+barrel life do you have to chase all the variables? For those reasons I've always neglected seating depth. Certainly left potential accuracy on the table, but only really chased it on rifles I couldn't get to shoot anyway, so felt like a waste of time. Lots of people here smarter than me that have already chased this stuff out!

 

[Phil Rizzo]

Those in the know, don't chase the lands, this is futile and silly.
What we do is, take velocity readings AFTER measuring the erosion of the lands distance, then add powder until the previous velocity is reached and this is why our BARREL TIME stays the same. It is not the distance to the rifling that governs the sweet spot, it is BARREL TIME HARMONICS that governs where the bullet exits in the barrel whip…

Too much emphasis is used on LAND DISTANCE, it really means little when you have multiple distances that will tune the same. This is why a barrel tuner works, it changes harmonics to match the barrel time, not the distance to the rifling is even necessary to know.

Cheers.

Distance to lands is merely a reference for a starting point with most VLD bullets.
With older style Nosler AB's and BT's I seat them very tight or touching for best accuracy. Same for sierra BTSP types.

 

[Hikinghunter]

Somebody else can use most of their barrel life proving and disproving. Or not.
That's up to them and their requirements.

Yup, that's why I asked on the forum. I achieved my desired accuracy without playing with seating depth, then burned 50 rounds to try different seating depths to see what would happen, which was pointless when I'd already gotten where I needed to go. I'm personally a statistics nerd, but I'll let the folks with small calibers shoot copious amounts of ammo so they can have large data sets. My poor 28nos would be a smooth bore if I tried that.

Berger does state that their hybrid hunter is specifically made to be accurate when loaded to SAAMI specs. Reading between the lines, one could assume it trades some aerodynamics for an ogive that is less sensitive to searing depth. Maybe that's what I got with my first two load workups, or maybe I just got lucky.

In any case, sounds like testing seating depth is still on the table for my next load work up, unless I luck out again and don't need to.

 

[fruitnut]

Rule number one:
Use a temperature stable powder. Even if it costs you some velocity.

There are plenty variables you can't get a grip on.
Lock down the ones you can.

You can't lock down anything with 3 shot groups. The funny thing is the guys wasting components are the ones chasing 3 shot groups. Guys who realize how much it takes to really lock something down, don't waste the ammo on any of that. The guy at Hammer bullets obviously has good rifles. That's a big part of the equation. He says load development is 10-15 shoots and he's ready to hunt. I'll follow his advice.

 

[Phil Rizzo]

I don't know how we went from Berger Hybrids to Hammers but I know this:

You aren't all that concerned with squeezing out the best precision your rifle has to offer, possibly because it's not necessary to begin with, if you don't pay attention to seating depth in some form or fashion, using Berger EH or HT.

Hammer bullets are in no way similar dude.
Not in composition or shape or purpose.

I'd listen to Mr Hammer too if I was shooting Hammers, like you said.
So why wouldnt you listen to Mr Berger when shooting Bergers?

 

[carpassasin]

The harmonics is why the BOSS system on browning and some Winchesters work.

 

[Phil Rizzo]

The harmonics is why the BOSS system on browning and some Winchesters work.

It helped them hang with factory M700's back in the day, also.
They were money at one time!

 

[MagnumManiac]

What happens to barrel harmonics when you develop a load at 90F in summer and then going hunting in winter at 20F? Velocity drops, barrel time changes, load is out of whack. So, I guess we have several loads at various charge weights? One for each temperature?

If done correctly, your load should be stable across a wide node that is NOT influenced by velocity changes, if it is not stable, it is NOT tuned properly or correctly.

If you want precision stable loads, use single base powders that are temp insensitive. Nearly ALL double base powders are temp sensitive, regardless of factory spin. Just the amount varies.

Cheers.