How far off the Lands?

[Sgt.RockRules04]

How far off the lands?
Ok , i've read the following reloading methods: Lee,Hornady 7th,Nosler 6th,Speer 14th,Lyman 48 & 49th(reloading for about 3 years rifle & pistol,consider myself an intermediate student of this game).They are all talking about "safe" distance from the lands for obvious liability reasons,I understand their position.What i'm finding is: after measuring OAL to the lands & then coming back say 10-15 thousands, that sometimes it feels & looks like bullets are touching lands?.I base this observation on marks on the bullets' ogive(after loading into chamber with bolt closed).Now, I've also learned that each Bullet manufact'r has diff/several machines that (extrude?) make these bullets,& therefore, their ogives are diff.All i'm really trying to determine is variance of ogives(Sierra matchking bthp .223 69gr Savage Model 12) & of course Best accuracy, while remaining "safe".I have friends who are competitive long distance rifle guys who load .223 onto lands??!! which i would never do!, but,it's very confusing to try to extrapolate the real truth from all this info & come out "safe" & on top of Best accuracy? SgtRock04

 

[bearhunter]

Depends on how tight the tolerances are in your chamber. If you notice stretching or expansion on your cases, play it safe and run from .015 to .025. If you have a tight, match style chamber .005 is safe. If you're running a bench rest chamber, well most bench rester shooters, jam the bullets right into the lands. They also have to turn the necks so the cartridges will chamber. Tolerances are the key, if you have a generous chamber, in example 7.62x51 Nato and you're using 308Win dies, you should have a longer jump into the lands.

 

[H4831]

I remember Jack O'Connor writing on this subject in Outdoor Life Magazine. Anyone who followed Jack in print, knew that he loaded, and recommended loading, hunting loads heavy.
He said the danger in loading rhe bullets into the lands was as follows. While hunting you chamber a round. Later, you go to take it out and the bullet is so tight in the rifling that it stays there, spilling powder all over the place and you are left with a bullet stuck in the barrel of a rifle.
Until then I was afraid of raising too much pressure by seating a bullet into the lands. After reading the O'Connor article I started experimenting with loading to the lands. With rifles in several calibres that I have tried, I have never noticed the slightest bit of pressure difference, whether the bullet touched the lands, or had a distance to go to them.
In the technical explanations of it that I have read, they say yes, there is a spike in pressure with the bullet in the lands. However, this occurs well before peak pressure is reached, so is immaterial to overall peak pressure. They tell me that peak pressure is reached in a bottle neck centerfire after the bullet is well into the barrel.
Later, I read Parker Ackley's books and he said basically the same thing.

 

[hunter5425]

H4831 has it right but I might add that each rifle and bullet combination is a new game. Most rifles shoot best with the bullets as close to he lands as possible but for hunting I now keep them at least .020 of the lands ( ask me why ). Also give identical loads each rifle will show pressures at different times so you must experiment to find what your rifle prefers in terms of seating depth and of course powder charge.

 

[bearhunter]

Bruce, your explanation is right on the money. I always like to err on the side of safe and practical though. Extending the bullets tight against the lands can really cause some concern at a critical moment. I've seen it happen several times when a cartridge was ejected from the chamber, without being fired of course and the bullet staying behind, firmly lodged in the leade.

As far as chamber dimensions go, even PO Ackley admitted that the book was still out as to the effects on pressures. I do agree with everything you printed above though.

 

[Huntin' Gun]

H4831 has it right but I might add that each rifle and bullet combination is a new game. Most rifles shoot best with the bullets as close to he lands as possible but for hunting I now keep them at least .020 of the lands ( ask me why ). Also give identical loads each rifle will show pressures at different times so you must experiment to find what your rifle prefers in terms of seating depth and of course powder charge.

Okay, I'll bite... Why 0.020 off the lands? That's what I do because that's what I was taught [for a pressure issue that H4831 just said doesn't exist].

 

[hunter5425]

There seems to be enough variation in OAL with some bullets that any closer risks getting a bullet stuck in the rifling. This happened to me on a mule deer hunt where I had my bullets seated .007 off the lands. I saw a buck and loaded a round in the chamber but I reconsidered as he was too small so I opened the action and powder poured out of the bulletless case ,a split second later up pops the biggest buck I was to see on the hunt, he trotted away with me standing with a non functioning rifle. As a result I give myself a little extra margin of safety and seat hunting bullets .020 " off.