seating depth 102nd post I think

[denobravo]

I had a good and respected friend convince me to doo a seating depth test before my ladder test
I usually test "in the lands"
So I tried it and was very surprised
Can anyone explain the science behind the test as it will help me "believe" as I go forward
my old way was ladder and then an OCW
or just ocw
How does this test work..seems like speed makes the harmonics as the depth changes pressure
but I would really like to hear (read) the science of it
thanks guys

 

[fguffey]

Can anyone explain the science behind the test as it will help me "believe" as I go forward
my old way was ladder and then an OCW

I am not the fan of sticking the bullet into the lands. I want my bullets to have that running start. When my bullets hit the rifling I want the bullet to have 'that jump'. I do not want my bullet to slow down. if the bullet slows down it has to get started again.

F. Guffey

 

[natdscott]

I am not the fan of sticking the bullet into the lands. I want my bullets to have that running start. When my bullets hit the rifling I want the bullet to have 'that jump'. I do not want my bullet to slow down. if the bullet slows down it has to get started again.

F. Guffey

What?!

Please explain in more detail, for all of us, what you mean by "slowing down" and starting up again?

I'm not saying you're wrong, in application, but I'm not following your logic.

 

[mike a]

I had a good and respected friend convince me to doo a seating depth test before my ladder test
I usually test "in the lands"
So I tried it and was very surprised
Can anyone explain the science behind the test as it will help me "believe" as I go forward
my old way was ladder and then an OCW
or just ocw
How does this test work..seems like speed makes the harmonics as the depth changes pressure
but I would really like to hear (read) the science of it
thanks guys

I don't understand the science either. I do a quick powder latter to make sure I'm not in a scatter node (300 yrds) then a Berger course seat test (100 yds) then a full on OCW charge test (300 yrds) then fine tune seating, then hope my lot number lasts and lands erode slowly, and it's cleaned right and etc. etc.

 

[fguffey]

Please explain in more detail, for all of us, what you mean by "slowing down" and starting up again?

If I load a bullet into the lands the bullet is setting at a dead stop, to get past the lands it has to 'get moving'.

And then there is the 'on the other hand' as in the bullet taking off with 'the jump' or running start. When the bullet hits the lands it slows down, not much but the slow down and causes the pressure to rise, the pressure does not rise much. That is the reason I like the bullet to hit the lands 'a moving', I want my bullet past the lands before the bullet knows the lands are there. It requires more pressure to get the bullet to move when the bullet is setting against the rifling.

F. Guffey

 

[ballisticdaddy]

The link shown below explains the seating depth testing and suggests large increments of jump, I personally go in .010 each.
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

 

[powderbrake]

I can't explain the science of "into the lands", and I don't care. I typically start all tests at just touching the lands, then when I get close to the correct powder charge, I increase the depth into the lands in small increments to find the best depth. Occasionally I also check the jump.
I have yet to have one of my rifles shoot better with a jump. I am NOT denying others who find a jump to give better groups, it just hasn't happened to me.

I even seat the Berger 105 Hybrid .010 into the lands. The next time out I am going to seat a few with a jump of up to .120 like the link in ballisticdaddy's post, just to make sure that I am not missing an opportunity for more accuracy.

 

[jimmymac]

...and then there are reloaders who never jump a bullet and shoot groups so small it often looks like a single bullet hole. I’m a fan of finding out what the target tells me and going with that.

 

[ballisticdaddy]

I can't explain the science of "into the lands", and I don't care. I typically start all tests at just touching the lands, then when I get close to the correct powder charge, I increase the depth into the lands in small increments to find the best depth. Occasionally I also check the jump.
I have yet to have one of my rifles shoot better with a jump. I am NOT denying others who find a jump to give better groups, it just hasn't happened to me.

I even seat the Berger 105 Hybrid .010 into the lands. The next time out I am going to seat a few with a jump of up to .120 like the link in ballisticdaddy's post, just to make sure that I am not missing an opportunity for more accuracy.

Just finished a 6BR build and when doing seating depth testing with the Berger 105 hybrid, I was able to shoot the same group size at touching the lands as with a .040 jump. It appears there is a range that can be found at multiple seating depths that would give the similar results. I for one did not believe the seating depth was all that important until recently.

 

[mike a]

Just finished a 6BR build and when doing seating depth testing with the Berger 105 hybrid, I was able to shoot the same group size at touching the lands as with a .040 jump. It appears there is a range that can be found at multiple seating depths that would give the similar results. I for one did not believe the seating depth was all that important until recently.

And the Berger seat test shows 10,40,80 & 120 jump. So your in the +/- .040 range and seat depth may be very important but not as sensative to small adjustments as I've always thought.

 

[denobravo]

What?!

Please explain in more detail, for all of us, what you mean by "slowing down" and starting up again?

I'm not saying you're wrong, in application, but I'm not following your logic.

I dont remember where I read nor who the expert was, but
he stated that the bullet actually stops for a nano of a nano second before continuing
so I do understand the premise

 

[denobravo]

And the Berger seat test shows 10,40,80 & 120 jump. So your in the +/- .040 range and seat depth may be very important but not as sensative to small adjustments as I've always thought.

I agree, I think 10k at a time is more time and material worthy

 

[denobravo]

Just finished a 6BR build and when doing seating depth testing with the Berger 105 hybrid, I was able to shoot the same group size at touching the lands as with a .040 jump. It appears there is a range that can be found at multiple seating depths that would give the similar results. I for one did not believe the seating depth was all that important until recently.

yup...me also...still learning and proving what I read
hope to get solid conclusions some day LOL

 

[mike a]

I dont remember where I read nor who the expert was, but
he stated that the bullet actually stops for a nano of a nano second before continuing
so I do understand the premise

Starts, stops and starts again? Hahahahahah it's not April 1st yet man. Hahahahahah, hohohohoh

 

[denobravo]

Starts, stops and starts again? Hahahahahah it's not April 1st yet man. Hahahahahah, hohohohoh

what if it could be proven...
maybe your concept of time or stopping and and starting is wrong?
even for a small small small moment..you cant conceive it?

 

[JFrank]

If I load a bullet into the lands the bullet is setting at a dead stop, to get past the lands it has to 'get moving'.

And then there is the 'on the other hand' as in the bullet taking off with 'the jump' or running start. When the bullet hits the lands it slows down, not much but the slow down and causes the pressure to rise, the pressure does not rise much. That is the reason I like the bullet to hit the lands 'a moving', I want my bullet past the lands before the bullet knows the lands are there. It requires more pressure to get the bullet to move when the bullet is setting against the rifling.

F. Guffey

I had a good and respected friend convince me to doo a seating depth test before my ladder test
I usually test "in the lands"
So I tried it and was very surprised
Can anyone explain the science behind the test as it will help me "believe" as I go forward
my old way was ladder and then an OCW
or just ocw
How does this test work..seems like speed makes the harmonics as the depth changes pressure
but I would really like to hear (read) the science of it
thanks guys

May I ask if your testing a VLD Secant ogive projectile?

 

[mike a]

what if it could be proven...
maybe your concept of time or stopping and and starting is wrong?
even for a small small small moment..you cant conceive it?

That's it, concept of time. Quantum physics, string theory. I don't mean to be sarcastic but hahahahaha hohohihihohohihi

 

[Lefty Trigger]

Would that Berger seating test work with any brand/type bullet or just the Berger VLD's?

 

[ClassCat]

50,000 + - Constant detonation Pressure PSI. The only thing the Jam or Jumping does is change the pressure curve and barrel harmonics. On a PPC it is more like 60,000-70,000. BTW , That was tested with a strain gauge

 

[denobravo]

50,000 + - Constant detonation Pressure PSI. The only thing the Jam or Jumping does is change the pressure curve and barrel harmonics. On a PPC it is more like 60,000-70,000. BTW , That was tested with a strain gauge

thank you