For the best possible Accuracy for "Targets" and for "Hunting".

Question:
When Developing my Long Distance "Target" Loads, I Seat Bullets:

Choices:
1. 0.010" Into-the-Lands
2. 0.005" Into-the-Lands
3. 0.000" - Kiss the Lands
4. Some distance off the Lands.
5. Other.

Question:
For my Long Distance "Hunting" Loads, I Seat Bullets:

Choices:
6. 0.010" Into-the-Lands
7. 0.005" Into-the-Lands
8. 0.000" - Kiss the Lands
9. Some distance off the Lands.
10. Other.

 

I always try to start .010 off the lands, and then adjust from there for accuracy. Or I run magazine length and adjust from there. I do this if I can't reach the lands feeding from the magazine.

I seat them where every my rifle tells me to. Rifles are like wives. Everyone has a mind of it's own, and if you ignore them, your life will be miserable.

quote:

Originally posted by Antelope Sniper:
I seat them where every my rifle tells me to. Rifles are like wives. Everyone has a mind of it's own, and if you ignore them, your life will be miserable.

+1

Hunting ammo needs to fit the mag, feed and extract without pulling the bullet out and spilling powder all of the place leaving the bullet in the bore.....

FL sizing helps in that respect as well but is not necessary with once or twice fired brass.

quote:

Originally posted by Antelope Sniper:
I seat them where every my rifle tells me to. Rifles are like wives. Everyone has a mind of it's own, and if you ignore them, your life will be miserable.

What HC is asking is "what is your chosen starting point as far as seating depth for your test loads"

I talked to a guy at the range who is a big time F-Class competitor and he believes in starting off of the rifling.

Some say start development .010" INTO the lands. Others say this is outdated.

I usually start .020" to .030" off of the lands, then when I find something that looks promising, test depths from there both forward and deeper.

Ah, I see.

Target bullets start out at 10 thou off the lands unless the bullet maker specifies in to the lands in which case that is where I will start.

If is goes magazine length then all well and good, if not I single feed.

Hunting ammo gets seated at a calibre's worth of shank in the neck if I can manage it. I get good accuracy with hunting style bullets anywhere from 20 to 160 thou off the lands in various rifles and with various bullets. For example the 150 gr .308 Speer BTSP doesn't have much full diameter shank and responds better to, I think, the better neck tension of being seated deep in the neck is more important than a short jump to the rifling.

In the case of bullets with very little full diameter shank, like the lighter Berger VLDs, I seat into the rifling for the same reason.

I voted "other" in both categories.

Bullet seating depth is critical for best accuracy. It also effects both pressure and velocity.

I WISH there was a magic formula to figure out the seating depth for best accuracy..... but I don't believe there is one. Every barrel is different.

Other than determining whether a loaded round will funtion through a rifle's magazine, measurment of OAL is USELESS... IMHO(especially with hollow point bullets)! Even good quality bullets can vary greatly in OAL.

I would suggest getting a good quality bullet comparitor. I like the RCBS Case Mic, but there are other good tools out there.

While overall cartridge length (OAL) will vary with bullets of different weights and shapes, for best accuracy, the relationship of the bearing surface of the bullet and the origin of the bore's lands must remain the same regardless of the bullet shape or weight.

Unfortunately, finding this magic measurement is a trial and error process. But once you establish the caliper measurement of bullet bearing surface to lands that your rifle likes, it will remain the same measurment for all bullet weights and shapes IN THAT RIFLE.

quote:

But once you establish the caliper measurement of bullet bearing surface to lands that your rifle likes, it will remain the same measurment for all bullet weights and shapes IN THAT RIFLE.

Are you SURE about that?

quote:

"what is your chosen starting point as far as seating depth for your test loads"

My typical starting point is .010 off, or magazine length, which ever is less.

quote:

Originally posted by DaMan:
...once you establish the caliper measurement of bullet bearing surface to lands that your rifle likes, it will remain the same measurment for all bullet weights and shapes IN THAT RIFLE.

I'm real glad it works that way for you, but I've never seen it happen.

The "Harmonic" is different for each Bullet Weight and for each different Bullet Manufacturer in my rifles.

Plus there is the Changing Throat(Distance to the Lead) which tends to change the Harmonic as well. It typically moves enough to see a difference in Length for 100-shots on the Barrels I've had.

Amazing how we all see different things.

quote:

Originally posted by rcamuglia:

quote:

But once you establish the caliper measurement of bullet bearing surface to lands that your rifle likes, it will remain the same measurment for all bullet weights and shapes IN THAT RIFLE.

Are you SURE about that?

That's been my experience over the years and what the folks at Sinclair International told me years ago.

There might be a very few exceptions out there. If you find any, I would be eager to hear about them.

quote:

Originally posted by Hot Core:
Plus there is the Changing Throat(Distance to the Lead) which tends to change the Harmonic as well. It typically moves enough to see a difference in Length for 100-shots on the Barrels I've had.

Damn! That's rapid throat erosion!

The instructions on my Brownells throat erosion gauge says, "Insert in empty chamber and take reading every 1,000 rounds to accurately measure and track barrel throat erosion."

Probably depends a lot on how much Powder is being burned and the Bullet Weight.

I just "save a Bullet" inside the Die Box and use it with the old reliable Cleaning Rod Method and Record the Length on a sheet which is also inside the Die Box to watch for Throat Erosion. Easy and quick to do. I typically check it with every new 100-count box of Bullets as it is opened, since I have to determine if they changed the Ogive or not anyhow.

I Agree the smaller Powder quantity Cartridges do not move nearly as much as the larger ones.

I start my load development at 0.010" off the lands and adjust from there.

I find SMKs shoot fine .01" off, that's where I start everything.