VLD seating depth sensitivity question

[Dave Way]

I have a 6.5x47L with a long free-bore of .255". I won't take the time to explain all the reasons for that but one of the reasons I designed it that way was for a 142 gr. bullet I no longer shoot. Looking at the bearing surface lengths of various bullets, I decided I should be able to use 130 gr. Berger VLD's. I have never shot VLD's before and heard they can be depth sensitive.

I shot a ladder at 500 yards and came up with a good powder node using about as much H4350 as will fit in the case. Then I took it out to 1,000 to test seating depths and was surprised with the results.

Test # 1, 1/12/19 Temperature 28 degrees. Wind light, <2mph. 1,000 yards.

.010" into lands 14.2" 5 shots

.005" into lands 13.5" 5 shots

.005 off lands 5.1" 5 shots

I was surprised at the difference in the groups. At this point I decided I would test small increments on either side of .005" off. This test was probably even more surprising.

Test # 2, 1/14/19 Temperature 10 degrees. Wind light, <1mph. 1,000 yards.

.003" off lands 10.2" 5 shots

.005" off lands 3.2" 5 shots

.007" off lands 10.7" 5 shots


.003" off lands, 2" orange dot.


.005" off lands, 2" orange dot.

Of course I'm happy with these groups at .005" off, but does this depth sensitivity seem normal for VLD's in your experience?

Thanks-Dave.

 

[Willow]

I wouldn't say it is surprising but as you have discovered it pays to test. I run 180gr vlds in my 280AI and while it will shoot with a decent jam I also found it likes a 40 thou jump too. Anything in between was ordinary.

 

[mikecr]

Your seating window seems awfully narrow, to nonexistent. Perhaps due to the cold temperature & it's difference test to test.
I would suspect this as unreliable, and do Berger's recommended full seating testing for something practical. I would also pre-foul/pre-warm the barrel before shooting ammo kept at a temperature it is expected to be at in the field.

 

[Dave Way]

Your seating window seems awfully narrow, to nonexistent. Perhaps due to the cold temperature & it's difference test to test.
I would suspect this as unreliable, and do Berger's recommended full seating testing for something practical. I would also pre-foul/pre-warm the barrel before shooting ammo kept at a temperature it is expected to be at in the field.

Seemed pretty narrow to me too but this is my first experience with VLD's. I do plan on testing in the spring under more normal conditions but I was bored and wanted to do a little early testing-long winter you know. The ammo was at 70 degrees or so in my truck and the barrel was warm from being fouled and brought on target but it's still not the same as shooting under expected competition conditions. Thanks-Dave.

 

[HTSmith]

Take what I say with a grain of salt because I'm not the most sophisticated reloader, but I started out with the Berger VLD's about 12 years ago or so. Back then everyone said the VLD's had to be jammed so I jammed'em. Couldn't get them to shoot worth a hoot. Then I started backing off the lands and the "magic" happened at .025 off. I was a happy boy until I had to change lots of bullets. I loaded the new ones .025 off and my .25 MOA load had become .7MOA. Yikes!

I'll shorten the story to say that at .028" off the new bullets closed back up. So in my experience .003" can make a big difference.

 

[Ned Ludd]

Bullets tune in where they tune in. I have a number of excellent VLD loads with different bullets that tuned in at approximately .004" and .007" into the lands, and approximately .018" to .024" off the lands. I will generally choose the window off the lands because it is usually wider, and I don't have to be concerned with other issues involved with seating bullets into the lands. I have never found any evidence to support the commonly heard saying that VLDs need to be seated into the lands, or that they must be finicky with regard to seating depth. Some may be, many others are not.

 

[dcali]

That is more sensitive than my experience shows. Other shooters whose experience I trust have reported similar results to yours.

I’m also not convinced that VLDs are more sensitive per se. I’ve shot some that were as easy dial in as any tangent ogive bullet. So there has to be more to it. I’m certain that it is not the secant ogive alone that causes sensitivity.

That said, it is what it is. I’d be nervous about shooting that tight a window, but I’m sure it can be done if you’re careful and stay on top of tuning. Just for kicks you might want to try some much longer jumps. I’ve found that in my .308, adding .080-.100 can also produce good groups.

 

[JFrank]

I have a 6.5x47L with a long free-bore of .255". I won't take the time to explain all the reasons for that but one of the reasons I designed it that way was for a 142 gr. bullet I no longer shoot. Looking at the bearing surface lengths of various bullets, I decided I should be able to use 130 gr. Berger VLD's. I have never shot VLD's before and heard they can be depth sensitive.

I shot a ladder at 500 yards and came up with a good powder node using about as much H4350 as will fit in the case. Then I took it out to 1,000 to test seating depths and was surprised with the results.

Test # 1, 1/12/19 Temperature 28 degrees. Wind light, <2mph. 1,000 yards.

.010" into lands 14.2" 5 shots

.005" into lands 13.5" 5 shots

.005 off lands 5.1" 5 shots

I was surprised at the difference in the groups. At this point I decided I would test small increments on either side of .005" off. This test was probably even more surprising.

Test # 2, 1/14/19 Temperature 10 degrees. Wind light, <1mph. 1,000 yards.

.003" off lands 10.2" 5 shots

.005" off lands 3.2" 5 shots

.007" off lands 10.7" 5 shots

View attachment 1084276
.003" off lands, 2" orange dot.

View attachment 1084277
.005" off lands, 2" orange dot.

Of course I'm happy with these groups at .005" off, but does this depth sensitivity seem normal for VLD's in your experience?

Thanks-Dave.

As God said onto Moses,

I am that I am..

Nice shooting

 

[dsculley]

I would highly suggest that you perform the Berger Seating Depth test. I am loading the 140's at 0.070" off the lands. I have a wide node at that depth. This test will help you figure out what is best in your rifle.