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Initial seating depth test

OmegaRed

OmegaRed

Novice reloader
6BR
30.8g RL15
105VLD's

Just did the Berger recommended:

1. .010″ into the lands (jam) 3 rounds 0.01 1.8065
2. .040″ off the lands (jump) 3 rounds -0.04 1.7565
3. .080″ off the lands (jump) 3 rounds -0.08 1.7165
4. .120″ off the lands (jump) 3 rounds -0.12 1.6765

The first 2 were pretty much identical group sizing (with #2 being tighter vertical and closer to POA if that matters). I split the difference and went to .020 jump (1.7765) and that shrunk the group size to .435".

Both 1 and 2 had ES of 12 and SD of 6 for the 3 shot groups. 1 avg was 2900 and 2 avg was 2870.

That being said, is there any which way I should be moving in .003 increments? Or just load a bunch of increments up and test? Thanks in advance.
 

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This is just me others may have different results. I tune out horizontal with seating depth and vertical with powder.
If the horizontal group at .020 was not wind don't let it fool you because there was no vertical. Look for a seating depth where the group tightens up on the horizontal and preferably pretty tight vertical then make final adjustments with powder or a tuner
 
After thinking about it last night, I am curious to whether there is any sort of pattern in this, more so, is there a linear progression to the groups tightening or loosening. It's pretty generally regarded that .003" increments are significant jumps, and that you can pass over a favorable seating depth more than that.

So what I'm getting at, is can you tune like you mentioned, .025,.030,.035, and they "should" all shoot somewhere gradually getting tighter the closer you get to the sweet spot seating depth? Or will it be black and white. This one is good, this one is not.

Thanks for the help.
 
I'm not sue I agree with those seating depths. You go from .010 jamb to .040 off? That a huge jump, no pun intended. I think I would start at .010 jamb if that gives you an even lands mark, then back off .010 at a time moving off. Once you get .020 or .030 off, not sure if things will change much. But then again, I don't shoot the long stuff.
 
WayneShaw said:
I'm not sue I agree with those seating depths. You go from .010 jamb to .040 off? That a huge jump, no pun intended. I think I would start at .010 jamb if that gives you an even lands mark, then back off .010 at a time moving off. Once you get .020 or .030 off, not sure if things will change much. But then again, I don't shoot the long stuff.
Click to expand...

Those are Bergers VLD seating depth guidelines.

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
 
OmegaRed said:
Those are Bergers VLD seating depth guidelines.

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
Click to expand...
I think the recommendations you speak of are meant to "rough" it in. If this were my rifle I would "rough in" between your first and second loads. I would probably go .005 into the lands and then work back out in .010 steps to your second depth and maybe out past your second depth if that seems to be heading in the right direction. Meaning 1.8015 and then .010 shorter etc until you find where it starts to open again. Throughout that string you may find a couple spots that seem to have potential and at that point fine tuning around it(them) in small increments should get you there. It looks to me like your third step away is starting to open up and give more horizontal and more vertical. So I doubt it pays to go further out. With the changes in shape between group 1 and group two I think you will find the answer somewhere between them. Good luck and your mileage may vary.
 
OmegaRed said:
Novice reloader
6BR
30.8g RL15
105VLD's

Just did the Berger recommended:

1. .010″ into the lands (jam) 3 rounds 0.01 1.8065
2. .040″ off the lands (jump) 3 rounds -0.04 1.7565
3. .080″ off the lands (jump) 3 rounds -0.08 1.7165
4. .120″ off the lands (jump) 3 rounds -0.12 1.6765

The first 2 were pretty much identical group sizing (with #2 being tighter vertical and closer to POA if that matters). I split the difference and went to .020 jump (1.7765) and that shrunk the group size to .435".

Both 1 and 2 had ES of 12 and SD of 6 for the 3 shot groups. 1 avg was 2900 and 2 avg was 2870.

That being said, is there any which way I should be moving in .003 increments? Or just load a bunch of increments up and test? Thanks in advance.
Click to expand...
OmegaRed,
IF you want to try to "tweak" that .435 group ( if you even want to) go .001-.002 to either side. My guess if that you are not on a seating depth accuracy node you are very, very, close. What was the SD at .020 off? Sometimes we try to get too fine when we are already there. Seating depth is the "coarse" adjustment. Velocity is the "fine" adjustment is what I go by.
Take care,
 
Berger's seating depth protocol is recommended for those testing VLD bullets that have no idea whatsoever where they might tune. IMO, it should only be used in the most extreme situations where someone simply can't get a bullet to tune in to anything reasonable. In other words, it's for getting some idea of where to start a finer increment seating depth test when you have no idea at all of where to start. As mentioned above, the amount you're moving the bullet in that protocol is so wide as to likely miss several decent spots between each increment. Further, moving the bullet by such large amounts will change both pressure and velocity, which defeats the whole purpose. So it's really designed only to get a very rough idea of where to start.

I have rarely found that most of the bullets I use prefer seating depths outside between about .005" off the lands and .025" off. I always start charge weight testing at .015" off, which is right in the middle of the typical range I test for optimal seating depth (~.006" off to .024" off) after I have determined the charge weight I will use. Moving the bullet .009" in either direction is not enough to change pressure/velocity enough that I can reliably detect it, so that's one less thing to worry about. If I fail to find an acceptable seating depth in that range, I would next back the charge off slightly and start moving the bullet into the lands, starting at about .005" in and going further over a few .003" increments, especially if it is a VLD bullet, or perhaps it would be better to say "one commonly known to prefer starting into the lands". The reasons I do it in this order are as follows: First, I don't care for having to be concerned about the adjustment in charge weight necessary to prevent pressure spikes when seating bullets into the lands at the same time I'm testing the bullet jumped. That is really trying to test two variables at the same time, which is a bad idea IMO. Second, as I mentioned, most of the bullets I shoot (including VLDs) have tuned in well off the lands. So I do it sequentially, starting with off the lands where my past experience suggests I'm most likely to find an optimal seating depth range, only testing a bullet into the lands if the first approach fails.
 
I was referred by multiple people as that being the place to start. Moreover than just this load, I'm looking to develop my future load workup order of operations.

Thanks qstaylorq, this is one of the most commonsense ways of doing things that I have found, and is just what I've been looking for. Appreciate your time.
 
centerlineseal said:
+1 on qstaylorq
Click to expand...
Another plus for qstaylorq. Do a search here and at BRC for posts made by James Mock. HE has posted pictures of how to find the tune on a rifle. It is very methodical, you will just have to adapt it to your cartridge/bullet.

It addresses both powder charge and seating depth. Do what your rifle tells you, not what the Internet tells you.
 
As you can see a lot of different methods to skin the cat. As long as you develop a method that works for you that you can repeat that gives good results.
This is a common method short range guys use. 3 different powder weights at the same seating depth a light to medium to upper load at jam then repeating at different seating depths coming out of the lands. You can see how critical a role seating depth plays
Look for a seating depth that shoots well at a wide load range of powder
 

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