Berger seating depth.

[biednick]

Secant ogive bullets (like VLDs) are more sensitive to seating depth than other ogive styles. They take more work to dial in. Almost every bullet has a fairly wide band where they perform well. Secant ogive bullets are no exception, but the location of that band tends to vary more than other bullets and precision tends to fall off more agressively outside of that band. I switched away from secants for most cartridges when the VLDs I used dried up a couple years ago. They work well once they're dialed in, but in my opinion you don't gain enough to justify the extra effort.

I wrote this up for a similar thread a while back. It's the process I use to load secant ogive bullets.

0. Decide what I consider acceptable precision for the gun I'm loading for. I'm looking for a load that meets or exceeds that level of precision, not the best load possible. For a hunting gun that's going to be dependant on the range I want to hunt and the size of the game I'm hunting. Be realistic here. Your 7lb 300 Win Mag isn't going to be a .5 MOA gun, and it doesn't need to be for hunting.

1. Load up 5 rounds each at mag length or .010 off the lands, -.040, -.080, and -.120. Shoot those into 4 groups.

2. Evaluate the groups, and select any that are smaller than what you consider acceptable. Usually I find 1, but sometimes 2.

3. Load up 10 rounds at the lengths you selected in step 2, +.010, and -.010. Shoot all those into seperate groups.

4. Pick the best, shoot a couple more 10 shot groups at that length to verify, and stop if you meet your goal.

5. If the groups from step 4 are unacceptable, repeat step 4 with the next largest group from step 3. Repeat this step until a good load is found, you're out of groups to test, or the smallest group is larger than your goal. If you don't find a good load start over with new components.

It takes about 70 rounds to dial it in. I very rarely find more than 1 acceptable group in step 2 and very rarely have to repeat step 4.

 

[Slick8]

Thank you. I have 175s for elk but bought these 140s for deer.

I see no need to shoot two different bullets for deer and elk unless you're wanting that super flat laser out to say 350. Then I'd pick something like the 150ish grain hammer if I wanted a dual purpose laser beam.

IMO with a hot rod like the 28 nosler pick one and use it for all purposes. It will save your barrel.

If you have the twist to run it the 180 hybrid is about as east to tune as it gets and again imo is the 7mm sweet spot. If twist is lacking the 168 and 175s are right there with it.

I'm running the 180s at 2840 in a short barreled 7 saum with .5 moa groups to 850.

 

[338 dude]

That's not at all what that link says. They say there's a .030-.040" wide window that gives good performance, but that window could be anywhere from a slight jam to .150 off the lands.

In my experience with Berger VLD hunting bullets what's written on their website is pretty accurate. I have found it to be accurate for every other secant ogive bullet I've tried too.

Been using 0.010 jam in my 65 x 284 norma with the 140 HVLD

 

[Barehandlineman11]

Ive had the 210 vld like jammed too .140 jump depending on barrel. I would opt out for the elite hunter. Much easier too tune.

 

[FEENIX]

That's not at all what that link says. They say there's a .030-.040" wide window that gives good performance, but that window could be anywhere from a slight jam to .150 off the lands.

In my experience with Berger VLD hunting bullets what's written on their website is pretty accurate. I have found it to be accurate for every other secant ogive bullet I've tried too.

No matter how you look at it, .030-.040" or .150" are measurements, distance, jump or whatever terminology one wants to use to understand the relationship of the bullet ogive to the lands. My personal experience like others is as noted per my original post.

 

[The_Whitetail_kid]

I've always had luck 15-20 thousandths off with the VLD's

 

[biednick]

No matter how you look at it, .030-.040" or .150" are measurements, distance, jump or whatever terminology one wants to use to understand the relationship of the bullet ogive to the lands. My personal experience like others is as noted per my original post.

The .030-.040" Berger references isn't a measurement from the ogive to the lands. They're saying the ideal seating depth will be a .030-.040" range, not that the ideal jump will be between .030 and .040. The ideal range per their findings could be .010-.050, .090-.120, or any other range that gives you a .030-.040" window.

I won't argue against your personal experience. However, your comment and the inclusion of the link to Berger's site implied to me that Berger's findings backed up your personal experience. They don't. Berger is saying something very different than you are.

 

[birddog 68]

X3 Every VLD I've ever shot has wanted at least .030".

At least!

 

[Rick Richard]

The .030-.040" Berger references isn't a measurement from the ogive to the lands. They're saying the ideal seating depth will be a .030-.040" range, not that the ideal jump will be between .030 and .040. The ideal range per their findings could be .010-.050, .090-.120, or any other range that gives you a .030-.040" window.

I won't argue against your personal experience. However, your comment and the inclusion of the link to Berger's site implied to me that Berger's findings backed up your personal experience. They don't. Berger is saying something very different than you are.

This is directly from Berger:

"When doing bullet seating depth testing your moves are always based on the CBTO (Cartridge Base to Ogive) distance to the lands! Never use the COAL ( Cartridge Over All Length)! This measurement is only used in regards to cartridges that are loaded to magazine length."

Not sure or understanding where you're coming from.

 

[bultinkle]

This is directly from Berger:

"When doing bullet seating depth testing your moves are always based on the CBTO (Cartridge Base to Ogive) distance to the lands! Never use the COAL ( Cartridge Over All Length)! This measurement is only used in regards to cartridges that are loaded to magazine length."

Not sure or understanding where you're coming from.

"What has been discovered is that VLD bullets shoot best when loaded to a CBTO that puts the bullet in a "sweet spot". This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands."

@biednick is pointing out that berger does not suggest .040 off the lands.

They say that there is a .030 -.040 wide zone of optimal distance that will be found anywhere from jammed to .150 off

 

[biednick]

This is directly from Berger:

"When doing bullet seating depth testing your moves are always based on the CBTO (Cartridge Base to Ogive) distance to the lands! Never use the COAL ( Cartridge Over All Length)! This measurement is only used in regards to cartridges that are loaded to magazine length."

Not sure or understanding where you're coming from.

The .030-.040" value in their article is not the range they have found will give good results. It's the size of the range they have found will give good results. They're not saying .030-.040" of jump will work well, they're saying you can fall anywhere in a .030-.040" range and get good results. The ends of that range need to be found by testing various seating depths. That's why their test procedure involves testing from just off the lands to more than .1" of jump.

Let's say you run their test, and find the group seated .090" off the lands gives the best results. For simplicity's sake we'll also say that's right in the middle of the range that gives you good results, and call that the ideal jump. There's a .030-.040" window that will perform well, which means you can fall +/-.015-.020" from the ideal jump without losing precision. We'll just say it's +/-.020 for simplicity. With an ideal jump of .090", you'll still get good results with .070-.110" of jump. That .070-.110" is what you'll measure relative to the lands using CBTO.

 

[birddog 68]

This is in the reloading forum and explains it but I think the OP has already found the answer.

Berger Bullets' Eric Stecker has just made available a tech bulletin in Word format.

You may download it here to save it one your own computer or read it online.



Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

Background

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifles. It can be difficult to get the VLD to group well (poor accuracy).

For years we encouraged shooters to use a base of cartridge to end of bearing surface OAL (I will use the term COAL to represent this dimension) which allows the VLD to touch the rifling or to be jammed in the rifling. This provided excellent results for many shooters but there were others who did not achieve top performance with the VLD jammed in their rifling. These shooters were left with the belief that the VLD bullets just won't shoot in their rifle.

Other groups of shooters were discouraged by our recommendation to touch the rifling. Some of these shooters knew that at some point during a target competition they will be asked to remove a live round. With the bullet jammed in the rifling there was a good chance the bullet will stick in the barrel which could result in an action full of powder. This is hard on a shooter during a match.

Yet another group of shooters who were discouraged by our recommendation to touch the rifling are those who feed through magazines or have long throats. Magazine length rounds loaded with VLDs could not touch the lands in most rifles (this is the specific reason that for years we said VLD bullets do not work well in a magazine). When a rifle could be single fed but was chambered with a long throat a loaded round that was as long as possible still would not touch the rifling.

Until recently, shooters who suffered from these realities were believed to be unable to achieve success with VLD bullets. Admittedly, we would receive the occasional report that a rifle shot very well when jumping the VLD bullets but we discounted these reports as anomalies. It was not until the VLD became very popular as a game hunting bullet that we were then able to learn the truth about getting the VLD bullets to shoot well in a large majority of rifles.

After we proved that the Berger VLD bullets are consistently and exceptionally capable of putting game down quickly we started promoting the VLD to hunters. We were nervous at first as we believe the VLD needed to be in the rifling to shoot well and we also knew that most hunters use a magazine and SAMMI chambers. Our ears were wide open as the feedback was received. It was surprising to hear that most shooters described precision results by saying "this is the best my rifle has ever shot."

We scratched our heads about this for awhile until we started getting feedback from hunters who were competition shooters as well. Many were the same guys who were telling us for years that the VLDs shoot great when jumped. Since a much larger number of shooters were using the VLD bullets with a jump we started comparing all the feedback and have discovered the common characteristics in successful reports which gave us the information needed to get VLD working in your rifle. We were able to relay these characteristics to several shooters who were struggling with VLD bullets. Each shooter reported success after applying our recommendation.


Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

Solution

The following has been verified by numerous shooters in many rifles using bullets of different calibers and weights. It is consistent for all VLD bullets. What has been discovered is that VLD bullets shoot best when loaded to a COAL that puts the bullet in a "sweet spot". This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands.

Note: When discussing jam and jump I am referring to the distance from the area of the bearing surface that engages the rifling and the rifling itself. There are many products that allow you to measure these critical dimensions. Some are better than others. I won't be going into the methods of measuring jam and jump. If you are not familiar with this aspect of reloading it is critically important that you understand this concept before you attempt this test.

Many reloaders feel (and I tend to agree) that meaningful COAL adjustments are .002 to .005. Every once in a while I might adjust the COAL by .010 but this seems like I am moving the bullet the length of a football field. The only way a shooter will be able to benefit from this situation is to let go of this opinion that more than .010 change is too much (me included).

Trying to find the COAL that puts you in the sweet spot by moving .002 to .010 will take so long the barrel may be worn out by the time you sort it out if you don't give up first. Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot.

Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
1. .010 into (touching) the lands (jam) 6 rounds
2. .040 off the lands (jump) 6 rounds
3. .080 off the lands (jump) 6 rounds
4. .120 off the lands (jump) 6 rounds

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds

Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting the VLD bullets very well (even at 100 yards).

Regards,
Eric Stecker
Master Bulletsmith

 

[FEENIX]

The .030-.040" Berger references isn't a measurement from the ogive to the lands. They're saying the ideal seating depth will be a .030-.040" range, not that the ideal jump will be between .030 and .040. The ideal range per their findings could be .010-.050, .090-.120, or any other range that gives you a .030-.040" window.

I won't argue against your personal experience. However, your comment and the inclusion of the link to Berger's site implied to me that Berger's findings backed up your personal experience. They don't. Berger is saying something very different than you are.

Yes, I am saying that "my" ideal seating depth is .030-.040" for most of my VLD loads, and yes, that is from bullet ogive to the lands (CBTO at the lands), and yes, that is my ideal jump. And yes, the range is from jam/touching the lands to the .150" for VLDs, and yes, I even have one at .160" to the lands/seating depth/jump.

 

[FEENIX]

"What has been discovered is that VLD bullets shoot best when loaded to a CBTO that puts the bullet in a "sweet spot". This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands."

I do not think anyone was disputing that.