Home Forums Reloading Varmint Rifles Bullet seating depth vs accuracy

Gents,

Been handloading for since I was 14, but now I'm really trying to understand the smaller details of making REALLY accurate ammunition.

I have always seated bullets just off the lands by .020" or so, and called it good. While at the SCI show in Reno, I was speaking with the guys from Barnes and they were telling my that
for their bullets I should seat the bullets much deeper in the case, as their bullets like a little "jump" to get into the barrel.

You guys can save me a bunch of range time here. Have any of you taken a load you like and just changed bullet seating depth in increments to find the sweet spot? Were there big differences in group size?

Thanks,
Michael

On one of my rifle seating .005 nearer the lands decreased the group size from 5/8" to sllightly under 1/2". While this may not seem like a lot it now gives a nice round group and has gotten rid of the mystery flyers I was getting.

As the old saying goes - every gun is an individual to itself, you will still have to experiment to see what your rifle likes. It is all about harmonics.

drover

+1

I begin load development by seating bullets .010 off the lands. If I need to seat bullets to a different seating depth to improve accuracy, I do so.
I had one rifle chambered in 6x47 that would only shoot well with bullets seated hard up against the lands.
Your rifle will tell you what seating depth works best.
What Drover said about tuning the barrel with loads is right on!!!

With Barnes bullets, I seat .050 off the lands.

All other cup and core bullets, I seat just barely touching the lands. If accuracy is not small group with the best load, I start jumping .005,.010,.025, and in .015 increments till I'm jumping .060.

I have one 270 and a 25/06 that likes jumping .040, everyother rifle that I own shoots tiny groups with the bullets touching. The 7 Mag is the most demanding of up against the lands seating depth.

Barnes bullets are Different.

The solid copper bullet doesent compress as easy as a copper jacketed bullet. Understanding this is critical for shooting Barnes bullets.

If you seat a solid copper bullet (more are being maufactured for "Green" reasons) tight to the lands, the hardness will create pressure increases that will effect your accuracy.

Some Barnes bullets I have loaded, shot best as much as .120 off the lands.

So don't be afraid to seat farther back.
Bob

Shotgunjock: As a "general rule" when seeking accuracy it is more often better to seat ones bullets so a smaller jump to the leades of the rifling for the bullet! This "general rule is "generally" better accuracy wise in my experience!
Having said that, I own a fleet of factory Varmint Rifles wherein the bullets NEED to jump several hundredths of an inch before they touch the rifling!
And yet they still shoot quite well.
I have MANY friends who call me and converse with me regarding bullet jump to the leades of the rifling!
I mean they sweat and worry and stay up nights railing and fretting agaisnt the current factory trend of "long throats" - nothing I can say to them will ease their concerns/worries!
So be that.
Two things mandate my longer bullet jumps to the leades of the rifling, for many of my Rifles.
One is the inability sometimes of using the Rifles magazine as when the bullets are seated near the leades of the rifling they no longer FIT down in the magazine!
I even have some Ruger #1 Rifles that I can't get a seated bullet near the rifling.
And another reason my bullets jump so far is because in order to keep with the standing safety rule of "one caliber length depth" of the bullet being seated in the case, then this length results in bullet jump in many of my Rifles!
Just because a bullet is jumping more than a few thousandths of an inch before it encounters the rifling does NOT mean you will have "poor accuracy"!
I have proven this to myself countless times over the last several decades.
Varying the bullet seating depth often WILL bring accuracy out of the doldrums for a particular Rifle.
On the custom Rifles I have had built I insist they be throated "short" or so they will easily accomodate a particular weight range of bullets.
I have loaded bullets by many custom bullet makers and MANY factory made bullets as well - I have as yet to load a single Barnes bullet!
I am going on 51 years of reloading this spring and the chances of me expanding my loading to include Barnes bullets is nil.
Wish I could be of more help with the Barnes segment of your inquiry.
Best of luck to you.
Hold into the wind
VarmintGuy

No magic being close to the lands. Benchrest shooters got us started in doing that. But they are only single loading. The bullet can be seated close to the lands but has to work through the magazine box. You can't always have both especially in short actions. I am currently working on a 338/350RemMag and the bullet is almost 0.2" from the lands. After two range sessions, I have two loads that shoot 1/2-3/4" at 100yds. Haven't started any fine tuning. Just trying several powders to see which the rifle likes best. This is strickly a hunting rifle and 1/2-3/4" will accomplish the task.Rick.

Right on.
I tested some loads with bullets seated close to the lands, then seated them deeper so the rounds would go thru the magazine, and groups were identical.

Accuracy with a specific component and seating depth is not always constant. There are times when throat erosion necessitates seating depth adjustment.

On occasion I have had new rifles require the bullet seated to the lands to shoot well. The COAL would not allow the ammo to be worked thru the magazine. They were essentially single shot rifles if you wanted to shoot for the best accuracy. They were hunting rifles so the COAL was reduced.

The more I shot them the better the groups became with the longer COAL until they plateaued after 200 rounds or more.

You just never know.

I've ran quite a few experiments over the years and the results varied. As mentioned, every rifle is a world unto itself and what works in one may not in another.
I generally start out kissing or as near to the lands as the magazine allows and if accuracy is wanting start back away. That way you have only one way to go.

Seems some one said "start at the start"

What I know..................which is limited is this. When I first got into reloading I started working with seating depth from the start. I had a Winchester M70 in 300 Win Mag. Once I found an accurate load I started messing with seating depth going from .010" to .08o" or so in .010" increments. I observed the groups go from 1" to 3."

I allways load new rounds just a CH off the lands to start with groups of varried powder charges. When I think I've got a powder charge picked out then I make loads with varried seating depts.
Alot of times changeing the seating depth will get rid of the unexplaind flyres.

That is exactly the way I do it except when using hand dies I do it from the bench. Just remember to change things one at a time when experimenting for the perfect load. I often have a problem remember that and it has cost me time and frustration.

You hunters loading into the lands are an accident waiting to happen. Or at best, you'll pull a bullet and have an action full of powder. That can be pretty embarassing when you're 50 miles from road's end.
I think RickSmith pretty much said it all.
Adjusting the bullet jump is the last thing I do as I've only seen it improve some loads slightly; I've never seen it change things enough to matter to a person that wasn't shooting some sort of competition.

Kissing and into aren't the same. Been at this 30 years and have yet to have a bullet pull from the case and dump powder in the action.
If you "never seen it change things enough to matter" you haven't been at it long or messed with with many examples.
Just this fall working up a load for my son's 243 with the Nosler E-tip adjusting the seating depth made the difference between writing the bullet off to a very accurate load.
I didn't follow my own advice and started off the lands as Nosler recommended similar to Barnes . Things were bad. Moved further away. Things were worse. Kissed the lands and all of a sudden tiny clusters happened just liked that. Seen the opposite as well with none other than Barnes. YMMV.

I've often wondered if some people that reload try different bullets in trying to find an accurate load and never vary seating depths. Then by luck, try a different bullet with a different ogive and a different distance to the lands that just happens to work. Granted, some rifles will not shoot certain bullets well no matter what.

fish head

I have seldom, I an trying to remember if ever, worked up a load when seating depth did not make a big difference.

It looks like I load differently than most here. I find a bullet and powder I like and make it work by adjusting seating depth. Yes there are guns that just won't shoot some bullets but I have not found that to be the norm as long as I stay within reasonable limits.

I've worked up many accurate loads with little concern about the seating depth for one reason or another and got great accuracy.
Other times it has made all the difference in the world. It certainly must be considered.

FVA, 30 years. Wow. I've got presses that are older than that by a good bit. And I doubt that your reloading skills are any better or as good as mine. As I posted, I've found depth to make a good load slightly better on occassion but I've never had a load go from a pray and spray to a one holer by adjusting the bullet jump. Maybe I'm a little more careful in my prep before I get to the depth part. I'd suggest you give that a try but from your post, it's apparent you already have all the answers.