Setting Bullet Depth to Lands

[smitty81]

I was reading through my grandfathers #3 Edition made in 1983. I read that you want to set the bullet up against the lands for the best accuracy. But I have also been told that you want to be .020 away from the lands for safety purposes. They showed grouping pictures comparing bullets set at .040 and bullets set against the lands. There was a HUGE difference!!!
The .040 grouping was about 1.5" groups and the bullets touching the lands was probable close to .50 grouping. Have the rules changed any since 1983? Like I said, Everything else I have read says .020

I am reloading for a 270. win, 130 gr. Pushed by 55 gr. H4831sc

I also might try loads of RL22.

What do you guys think about what the manual said about the seating depth and what depth do you guys seat away from the lands?

The book also said that the faster burning powder, the better unless its a heavier bullet, then you need the extra push, so it says to use a slower burning power.

What do you guys think about that?

 

[smitty81]

I was reading through my grandfathers #3 Edition made in 1983

By the way, Its a Hornady book if that matters.

 

[JD338]

Every rifle is different. You can try different seating depths to see what shoots best in your rifle.
Remember to make sure that the shells will feed through the magazine.
A good place to start is .015-.020" off the lands.

JD338

 

[old #7]

I remember the older manuals illustrating and instructing to seat the bullet so it just touched the lands for better accuracy. The farther away from the lands the more the bullet would "wobble" into the barrel.
I seat mine a few thousandths away to start, find the powder that the rifle and bullet likes the best and then play with the COL.
My Rem 700 - 270 likes IMR 4831

 

[Guest]

It's fine to seat the bullet touching the lands, if your rifle likes that. What you have to remember is that in doing so, you drastically increase 'start pressure' which means ultimately you will likely get very consistent, albeit lower velocities. You need to be very careful working these loads up (but in the heat of the summer is the time to do it) and start at the listed 'start charge' as the pressure curve will be moved to the left on the graph, if you are a math guy. If you're not, having the bullet seated touching the lands will cause much higher pressure for a given powder charge than seated off the lands a bit. Work with what you like, but be careful if you seat them touching not to over power the load right off the bat.

And don't seat Barnes bullets touching, as you'll get a nasty pressure spike you don't want.

 

[Guy Miner]

Sometimes a rifle/bullet combo will produce the best accuracy when the bullet is seated touching the lands. Sometimes it won't.

For hunting rifle reliability, it's better to load to magazine length, and avoid touching the lands. Chances are, it'll still be plenty accurate. Heck, my match ammo is loaded deliberately to not touch the lands, because it has to cycle from the magazine. A little jump is fine, it still shoots very well.

A number of times over the years at various rifle matches, I've seen someone have to remove a loaded round from their chamber. If they were loading long, into the lands, sometimes the bullet stuck in the rifling. When the bolt was pulled back, the bullet stayed stuck in the chamber, the powder all dumped inside the action of the rifle, and only the case was ejected.

It was a big enough problem to solve during a rifle match, I can only imagine what a horror story it could be on a hunting trip. It's amazing where all those little pieces of powder can hide in a rifle action!

Regards, Guy

 

[rick smith]

I never seat touching the lands. Many short actions will not allow the bullets to work in the magazine, you can get pressure spikes and there is always the possibility of the bullet getting stuck in the lands. Most WBY Mags will have the bullet out of the case before they touch the lands. You don't have to be against the lands for an accurate load. The closest any of my rounds are to the lands is 0.010" off. That is my normal starting point and I go off from there. It is not unusual for my loads to be 0.050" off the lands.Rick.

 

[Guest]

In my sleepiness last night I forgot to add that all of my rifles are limited by magazine length, and so if I load touching, I have to make them single shots. I'd need a bullet about a foot long to load touching the lands in my Weatherby, but it still shoots .25" groups at 100yds, so there must not be entirely too much magic in touching the lands. Tinkering is what this hobby is all about, just be careful and don't take a known max load with the bullet off the lands and load it up long enough to touch, as you'll experience a huge pressure spike.

 

[smitty81]

I was doing some thinking last night and decided to do this. I will make 3 rounds using H4831sc. I will make 3 or 4 groups of 3 and each group will be at a different depth.

I am then going to try the same thing but using RL22.

What do you think of this method?

 

[Guest]

Works great, just as long as you make sure to load close to the start load. A better choice might be to load through the range from start to max charge, and see what powder charge groups best. Initially, set all of these at the COL listed in the manual, or at least .020-.050" off the lands, and you'll be fine pressure-wise. Once you find the best powder charge, you can then tweak seating depth from there. I bet you find the rounds won't fit into the magazine with the bullet out far enough to touch the lands, which will make this discussion a bit moot.

 

[smitty81]

I was gonna keep the loads the same for every group but change the bullet depth between the groups.

 

[steve4102]

I was gonna keep the loads the same for every group but change the bullet depth between the groups.

That is fine tuning an already accurate load. Adjusting seating depth before you find an accurate bullet/powder/charge/primer combo will work, it's just kinda backwards and IMO more difficult.

 

[smitty81]

yea........i think i see what your saying now. Thanks guys

 

[Kerwhop]

I've had mixed results kissing the lands. With many chamberings you simply can't touch the lands unless your gunsmith uses a reamer with a short leade--same with most factory chamberings. There often just isn't enough bullet shank or magazine length to do it. I have some guns that I can't kiss to the lands and actually show an inverse trend; groups get better when I back off to a point.

I'm attracted to the Win short mags now becuase I've heard they have no freebore and thus allow touching the lands.

 

[Charlie-NY]

As a rule of thumb, cartridges that have bullets with limited jump to the rifling are more likely to have the bullet enter the bore more concentric and "should" yield better accuracy.

However, every rule of thumb has been broken and hunting rifles are better served with ammo that is short enough to fit the magazine and is off the rifling. Target work is a horse of a differnt color.

 

[rick smith]

Concentricity of the loaded round determines how straight the bullet will enter the lands, not how close it is to the lands. If your rounds aren't concentric, distance to the lands won't change the entry angle.Rick.

 

[Charlie-NY]

What about when the bearing surface of the bullet leaves the case neck (or nearly so) before it is engraved by the rifling? Plenty of room for misalignment here. Bullets that are fully supported by the case neck of concetric ammo should enter the rifling more consistently.

Just my 2 cents.

 

[Guest]

That 'ought' to be the case, but my Weatherby Mark V in 270Wby has such freebore that it is impossible for the bullet to be in the case neck and the rifling at all, and yet it shoots .25" groups (3 shots) at 100yds, from sandbags. Go figure, huh?

 

[Guy Miner]

Dubyam - good point. I load most of my "match" ammo to magazine length, and it has to make a pretty good jump to the rifling... Yet it still shoots very well. Some bullets seem to take the "jump" to the rifling better than others. I've always been pleased with the way the .30 cal Nosler comp bullets in both 155 & 168 grain versions make that jump.

With a hunting rifle... Well heck yes, I load to magazine length instead of out to touch the lands! :grin:

Sometimes loading to the lands, and staying short enough to function through the magazine can be accomplished, but often I've found it's one or the other.

Regards, Guy

 

[rick smith]

Charlie, your second sentence is almost a repeat of my first but doesn't agree with your first implication on misalingment.
You do not have to be close to the lands for excellent accuracy and being close to the lands will not effect the concentricity nor will being farther away from them.
Concentric rounds have a higher probability of accuracy than non-concentric rounds.
Distance from the lands has nothing to do with concentricity and has less effect on accuracy than does concentricity. If this were not true, all loads would be seated just into the lands and WBY rifles would never shoot accurately.Rick.