I have been reloading for a while, when working up a new load I usually start with my bullets 25 thousands from the lands which usually works pretty well. I was just wondering how close one can safely go to the lands and if you go closer will accuracy get better? I do use a OAL gauge and bullet comparator.
How close to the lands?
- Thread starter NHSHOOTER
- Start date
Generally closer is better, but not always. Some guy load until they touch the lands. I use a very unscientific approach and simply load one round as long as possible that will fit in the magazine. If it feeds and does not touch the lands then I load a few more and head to the range. If they shoot well then I call it good. If not I may experiment by loading some seated deeper but the only time I've found that approach to work was with copper Barnes bullets.
I have no idea how close to the lands I am, but know it would be impossible to get any closer unless I want to single feed my rounds. Since I'm primarily a hunter not a target shooter I'm not interested in that.
I have no idea how close to the lands I am, but know it would be impossible to get any closer unless I want to single feed my rounds. Since I'm primarily a hunter not a target shooter I'm not interested in that.
firewrench044
New member
Some bullets like to be close or touching the lands
some bullets like a short jump 10 to 20 thou.
and some like a big jump or can tolerate it
some barrels want bullets touching, some a small jump
some big jump
It is up to you to find what your bullet and barrel wants
some bullets like a short jump 10 to 20 thou.
and some like a big jump or can tolerate it
some barrels want bullets touching, some a small jump
some big jump
It is up to you to find what your bullet and barrel wants
all three of my R700 precision target rifles respond the best with a .030" jump. I did some testing in my .308 a few years back with 3 bullet length steps of "jammed" , .015 jump and a .030" jump. Didn't notice any significant change in accuracy. I'm just an amateur recreational precision handloader. You do need to be aware that is you "jam" the bullet into the lands this creates a substantial initial spike in pressure vs bullet jump.
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In the 1995 Precision Shooting Reloading Manual, the late Dan Hackett, a benchrest shooter, described a 220 Swift he had that he couldn't get to shoot 5 shots into better than about 3/8", with most groups being more like 1/2" at 100 yards. Most of us would be pretty pleased with a gun that shot this well, but this is a benchrest shooter we are talking about, so he wanted bugholes. He'd always seated bullets for this gun 0.020" off the lands because it was common knowledge among benchrest shooters at the time that this was the best jump. (Note that it had been common knowledge among benchrest shooters a generation earlier that contact with the lands was best.) Well, one day, in switching his load to a bullet that was 0.015" shorter than the first one he loaded, he accidentally adjusted his micrometer seating die in the wrong direction, turning 0.015" deeper and setting these bullets a whopping 0.050" off the lands. He had 20 rounds loaded before he noticed his mistake. He considered pulling them, but decided to shrug it off and just shoot them in practice. To his amazement, they gave him two 0.25" groups and two true bugholes down in the 1's.
So, what depth is best? The one that works best in your gun. Berger has found that in some guns the jump needs to be out as far as 0.150" to get the best our of the VLD bullets. They have a description of how to determine that best depth on their site.
How much better is best? Well, if you shoot at well as Dan Hackett did, then you can probably pick up pretty easily on even a small improvement. If you don't, you have a statistical problem. A typical target group's bullet hole distribution may be modeled by a pair of bell curves at right angles to one another, the random locations within which provide coordinates of the hole locations. Each curve has a standard deviation around the group center, and if the group is round, the SD's are equal. The error introduced by improperly tuned seating depth has it's own standard deviations that have to be added to the first two to get a resulting effect. If we treat Hackett's before group average as 0.5 inches and has after group average as 0.2", then seating to a better depth reduced a contributing standard deviation by 0.458". It's bigger than you'd expect because standard deviations interact such that they produce deviations equal to the square root of the sum of their squares. So, suppose your gun shoots 1" groups and your remove that same 0.458" SD from them, what will your new group size be?
√(1²-0.458²) = 0.889" or barely over 10% reduction. Can you even see a 10% reduction reliably? If you miss the tuning spot by 0.020" and that number increases to a 5% reduction, will you be able to tell?
That's the issue. You may or may not be able to tell. If depends how much the error contributes and how well the gun shoots with the error in force.
Incidentally, all fine tuning tricks are like that. Deburr flash holes or not? Outside turn necks or don't? All these kinds of improvements can be apparent in one gun and not in another depending how large other error sources are.
So, what depth is best? The one that works best in your gun. Berger has found that in some guns the jump needs to be out as far as 0.150" to get the best our of the VLD bullets. They have a description of how to determine that best depth on their site.
How much better is best? Well, if you shoot at well as Dan Hackett did, then you can probably pick up pretty easily on even a small improvement. If you don't, you have a statistical problem. A typical target group's bullet hole distribution may be modeled by a pair of bell curves at right angles to one another, the random locations within which provide coordinates of the hole locations. Each curve has a standard deviation around the group center, and if the group is round, the SD's are equal. The error introduced by improperly tuned seating depth has it's own standard deviations that have to be added to the first two to get a resulting effect. If we treat Hackett's before group average as 0.5 inches and has after group average as 0.2", then seating to a better depth reduced a contributing standard deviation by 0.458". It's bigger than you'd expect because standard deviations interact such that they produce deviations equal to the square root of the sum of their squares. So, suppose your gun shoots 1" groups and your remove that same 0.458" SD from them, what will your new group size be?
√(1²-0.458²) = 0.889" or barely over 10% reduction. Can you even see a 10% reduction reliably? If you miss the tuning spot by 0.020" and that number increases to a 5% reduction, will you be able to tell?
That's the issue. You may or may not be able to tell. If depends how much the error contributes and how well the gun shoots with the error in force.
Incidentally, all fine tuning tricks are like that. Deburr flash holes or not? Outside turn necks or don't? All these kinds of improvements can be apparent in one gun and not in another depending how large other error sources are.
>>>I was just wondering how close one can safely go to the lands and if you go closer will accuracy get better?<<<
With a cup and core bullet you can start out with them jammed if you work up from a start load. Usually close to the lands works better but accuracy is where you find it. There is no 100% sure way of predicting accuracy.
A 6mm Rem factory rifle does not allow touching the lands in a standard 700 Rem short action magazine. If you want to use the magazine the rounds have to be seated for a significant jump especially with pointy boat tails. Even so I have seen 6mm shoot really well with bullets that have to jump.
With a cup and core bullet you can start out with them jammed if you work up from a start load. Usually close to the lands works better but accuracy is where you find it. There is no 100% sure way of predicting accuracy.
A 6mm Rem factory rifle does not allow touching the lands in a standard 700 Rem short action magazine. If you want to use the magazine the rounds have to be seated for a significant jump especially with pointy boat tails. Even so I have seen 6mm shoot really well with bullets that have to jump.
First I determine the length of the chamber from the rifling to the bolt face. As you read through the responses that is not a priority. And then there is the question about how far off the lands. I am the fan of the running start, I want my bullets to have that 'jump'.
Rational, I want my bullet past the lands before the bullet know it is there. It requires more pressure to get a bullet started when it is jammed into the lands; there is nothing entertaining about wondering if the bullet is going to start moving before the rifle is rendered scrap.
Keep in mind, if the bullet is into the lands reduce the load.
When I build a rifle and take it to the range I normally take 120 rounds of 12 different loads with 10 rounds in each group. I use 12 different cases, different powder, and different bullets. The one consideration I do not factor in is the 'off, near or into the lands.
And then there are the tools, I use the minimum; I transfer the dimensions of the chamber to the seating die. It is so simple to zero the seating die and then adjust the seating stem to 'off the lands'. And if I do not want to start over the next day I save my transfer.
F. Guffey
I have never seen it discussed on the Internet it could have something to do with reloaders having a problem with concentration; I do not know.
When the bullet is setting at the lands or into the lands there is no vacuum in front of the bullet meaning the bullet is pushed from the rear. When the bullet is setting against the rifling the rifling offers resistance; remember the front of the bullet has nothing pulling it, the pullet is pushed. Then the bullet hits the rifling the bullet upsets, the upset distorts the bullet and the rear of the bullet increases in diameter.
A North Texas shooter offered to zero a rifle for a friend. He went to a sporting goods store to purchase ammo and then went to the range. He fired one round and then packed up what was left and went looking for a gun smith. The shooter was going to sue everybody , the manufacturer of the rifle, the sporting goods store etc. It took the smith 2 hours to open the bolt and remove the case. The smith asked to see the unfired ammo and the receipt. The receipt matched the ammo so the smith informed the shooter he could forget suing the store. He then checked the stamp on the barrel, the rifle was a 25/06, the ammo he purchased was 308 W.
And then all of the guessing started; how long was the bullet when it left the barrel? Had the shooter purchased good bullet he would have rendered the rifle scrap with the first shot. Try to remember; there was no vacuum in front of the bullet pulling it.
F. Guffey
When the bullet is setting at the lands or into the lands there is no vacuum in front of the bullet meaning the bullet is pushed from the rear. When the bullet is setting against the rifling the rifling offers resistance; remember the front of the bullet has nothing pulling it, the pullet is pushed. Then the bullet hits the rifling the bullet upsets, the upset distorts the bullet and the rear of the bullet increases in diameter.
A North Texas shooter offered to zero a rifle for a friend. He went to a sporting goods store to purchase ammo and then went to the range. He fired one round and then packed up what was left and went looking for a gun smith. The shooter was going to sue everybody , the manufacturer of the rifle, the sporting goods store etc. It took the smith 2 hours to open the bolt and remove the case. The smith asked to see the unfired ammo and the receipt. The receipt matched the ammo so the smith informed the shooter he could forget suing the store. He then checked the stamp on the barrel, the rifle was a 25/06, the ammo he purchased was 308 W.
And then all of the guessing started; how long was the bullet when it left the barrel? Had the shooter purchased good bullet he would have rendered the rifle scrap with the first shot. Try to remember; there was no vacuum in front of the bullet pulling it.
F. Guffey
reynolds357
New member
I start load work up in the lands and work back. Weathby cartridges being a noted exception.
Stats Shooter
New member
How close?
Assuming that the magazine isn't the limiting factor, I typically seat .002 off the lands.
So far I have not found a firearm where a bigger jump is better for accuracy...That doesn't mean there isn't a gun that prefers a big jump, just that none of mine or anyone else I have talked to ever have.
I do have 3 guns, that when using Sierra match kings, shoot the same at recommend COAL as they do with a short jump. So basically, just like everything else in reloading, it is chamber specific.
My only useful advice in this post is: if you aren't getting the accuracy you want, try moving closer to the lands....If that doesn't work, try a different bullet or powder, or both.
Assuming that the magazine isn't the limiting factor, I typically seat .002 off the lands.
So far I have not found a firearm where a bigger jump is better for accuracy...That doesn't mean there isn't a gun that prefers a big jump, just that none of mine or anyone else I have talked to ever have.
I do have 3 guns, that when using Sierra match kings, shoot the same at recommend COAL as they do with a short jump. So basically, just like everything else in reloading, it is chamber specific.
My only useful advice in this post is: if you aren't getting the accuracy you want, try moving closer to the lands....If that doesn't work, try a different bullet or powder, or both.
I won't; If I start sliding the bullet forward with a maximum recommended load of powder I am raising pressure. Not the kind of pressure that renders a rifle scrap but the kind of pressure that causes slight case head expansion. Reloaders claim some brass by FC (pick a brand) is soft and they know it is soft because they can only get two reloads from a case before the primer pocket gets loose.
When reloaders start sticking the bullet into the lands they should consider the perfect world is based on the perfect load. Reloaders do not purchase factory ammo; Normal case head expansion with factory over the counter ammo is .00025". If a reloader pulls the bullet and then seats the bullet into the lands the case head expansion will be greater than .00025.
I have increased the diameter of the case head to the point the primer fell out of the primer pocket when the bolt was opened with one firing. The flash hole increased in diameter, the primer pocket increased in diameter, the case head increased in diameter and the case head got shorter from the cup above the web the the case head. I know; most think that is all that can happen to a case when fired after that. Not true; reloaders have an infatuation with case head separation and want their cases to last forever but when the case body locks to the chamber and the case head is crushed there is no way to prevent the case head from separating from the case body.
I know; it is head space this and head space that and then we throw some of that moving the shoulder when sizing a case and firing a case
anyhow, if a reloader decides to stick the bullet into the lands reduce the powder charge. I am not the fan of maximum loads and I am not the fan of seating the bullet into the lands. I am the fan of the running start.
F. Guffey
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603Country
New member
I vote with Mr Guffey. I jam no bullets into the lands on any rifle I own. Maybe if I was a BR shooter or a long distance shooter I might feel differently, but if I was either of those I probably wouldn't be asking the question on the forum.
I generally measure the chamber and seat the bullet a hair shy of the lands. But, do check to see if a round with the bullet seated near the lands will feed through your rifle magazine.
I generally measure the chamber and seat the bullet a hair shy of the lands. But, do check to see if a round with the bullet seated near the lands will feed through your rifle magazine.
When I first started measuring seating depth and jump/jam I just assumed based off what I'd been told that .020 jump was going to give the best results and, indeed, in some gun/bullet/powder combos it was much better than the listed OAL in the manual. I recently read the above mentioned article and have done some testing and discovered that some of my combinations work much better with a larger jump than I would have ever thought.
What works best? As others have already said, it just depends on the combo, you'll have to buy more bullets, powder, and primers and go to the range and find out.
reynolds357
New member
Guffey, maximum overall length is determined by the chamber and the bullet shape. A berger vld and a flat nose of the same weight will not load to the same coal in the same rifle.
With all due respect, whether the bullet is "off" or "on" the lands there is always air in front of it because the barrel is open at the other end. Vacuum is simply the absence of air pressure.
Even if there was a vacuum in front of the bullet, the bullet would not be "pulled", it would still be pushed by the expanding gasses behind it. Vacuum does not pull anything.
Thanks