seating depth
- Thread starter Tjkiller
- Start date
markley
New member
are you wanting to seat as close to the lands as possible or are you just talking about by going what the oal says in a reloading book? I have yet to try and seat the bullet as close to the lands as possible but for seating the bullet for the oal for what it says in the book i just start way out in the seating depth and slowly work my way to what it needs to be. and if i set it too deep i pull the bullet out and then try reseating it. i would also make a dummy round so you know the seating depth.
Rustydust
Active member
This is difficult. Generaly speaking, the less jump to the rifling the better and I have guns that like the bullet seated WAY out. BUT, I have and have had a few guns that like to have a bit of running start before engaging the rifling. I guess that is all part of the fun of developing a tack driving load. Plus anything that helps you work up a load to hit something WAY out there is just OK with me.
hylander
Active member
As a general rule you need atleast the diameter of the beullet seated in the case.
Example: If you have a .224 flat based bullet, you need to seat the bullet atleast .224 deep into the case.
This will help the bullet get a stright shot into the Lands. This is more important for accuracy than getting the bullet near the Lands.
Example: If you have a .224 flat based bullet, you need to seat the bullet atleast .224 deep into the case.
This will help the bullet get a stright shot into the Lands. This is more important for accuracy than getting the bullet near the Lands.
I'll be interested to see everyone's replies on this thread myself! I usually start by measuring the particular bullet I want to use in whichever rifle, using a Hornady OAL guide. I'll measure the case (or just work with a trim length and max case length as my worst case), the bullet itself, and then the bullet + case to arrive at a maximum for my specific gun. And hylander is correct - try to keep at least a diameter's length inside the case neck. Then I start (hopefully) at something .015 to .025 lets say off of my gun's rifling. Some say if you move beyond .040 off, you'll not get best accuracy. However, for some of the shorter bullets, you may never be able to get anywhere even close to the rifling. And I've seen some long bullets too that could certainly be seated all the way up, but that didn't shoot worth a darn until I gave them more jump. Anyway, with a maximum overall length in mind, I'll usually get shorter not longer. One because I don't want to cause myself any accidents with pressure spikes, and two because I just find it is easier to start closer to maximum length and then work backwards from there... go in one direction only with my OAL/COL changes. Of course, if you are going to be limited by a magazine, this length becomes the maximum and your starting point then. But I have personally found NO good rules of thumb for seating depth that will work for all bullets in all rifles -- they all vary. Also, try to find your best powder charge first, holding all other variables constant. Then tweak it from there with seating depth changes until you find "the one".
In all the Rem 700's, 40'x, 788's, and all customs guns in all calibers that I have owned, in order to get down to shooting groups that are below .375, a proper measurement system that is accurate and repeatable is necessary. A guy can easily attain 3/4"-1" groups without a lot of anal measurement systems.
In all of the many guns custom and factory that I have owned, 5 guns or less did not like the bullets seated closer than 0.010 off the lands to jammed .030. One of those guns that liked the bullet to jump .040 is a Rem 25/06, Ruger 270, and 308's are all throated long.
I have used two systems to establish seating depth, the stony point(hornady now) with stony point (hornady) ogive gages and a split neck system(slice the neck to about .050 into the shoulder with a thin dremel cut off wheel). You insert the bullet into the case neck, close bolt, bullet will be pushed back in the case. You can use the stony point ogive gage or the Davidson ogive gage($12). With either system, you will have a learning curve.
I work up all my loads with the bullet just barrely touching the lands. Once the most accurate load is established, then start playing with seating depth, then primer. With most rifles, groups below 1/2" are attained quickly.
There is an old wives tale about having the bullet seated in the neck a caliber's depth...hog wash. If you want to get the bullet started straigh in the barrel, eliminate bullet jump...every benchrest shooter knows this.
Eliminating bullet jump is very difficult these days with the attitude that if a guy can not shoot a poly tip bullet or a VLD bullet, they can't kill anything. In many rifles that have a long leade, a Semi point bullet from sierra will establish extreme accuracy quickly. Sierra 50 and 55g Semi point bullets in 22 Caliber are nearly as accurate as Berger bullets, hard to tell the difference in accuracy in my custom BR rifles.
Reloading is a hobby in and of it's self. You can take this hobby to some very interesting depths. General rules of thumb are very tough, but the things that I have stated above are pretty much the same rules that have been around in benchrest shooting for many, many years.
Each rifle is unique in and of itself. As I stated above, it is very rare to find a rifle that shoots extremely tiny groups(a single bullet hole is just enlarged) by jumping bullets. There are exceptions to everything, but getting the bullets within 0.010 of the lands or jamming the lands for best accuracy holds almost universally true with all benchrest rifles and varmint rifles in 17, 22, and 6mm & 7mm calibers.
For example, Saturday I took a Ruger Stainless in 270 and I wanted to work up a load for the 110g Barnes tripple shock and the Sierra 110g Pro hunter. I knew from past experience that this rifle was one of those rare witches that loved about .040 bullet jump. I started off with .050 bullet jump on the Barnes tripple shock, using win 760, and win primers. I started shooting 3 shot groups. At 58.0g, I was shooting 1/2" three shot groups at 100, switched to 200 which equaled 1" groups. Next, the 110g Sierra's. Used the same load with .040 jump bullet seating depth, shot a .395 group at 100, and a .786 at 200. I next played with CCI250 and Fed 215 primers...things got worse...I called her done.
It is important to know how far the bullet likes to jump, touching the lands, or jammed the lands in a particular rifle so you can keep up with the leade growth over time...you simply "chase" the lands.
20 years ago a rifle that would shoot 1"groups was the cat's meow...not so any more. Shooters demand more and more of their rifles and their reloads. Along those lines, I want to mention that very suttle wind of 5mph will open a group up to over an inch if there is a "switch" from left to right. I had the unfortunate experience of wearing out 4 barrels before I learned of wind flags, they cost about $45-$65 and are one of the best investments that a serious reloader/shooter could have.
Using wind flags are pretty simple, left and right winds, go home and don't fire a shot if the wind is blowing in your face. If you have fired two shots with the wind blowing to the right, then the wind starts blowing to the left and the shot goes to the left, you know it was the wind, not your load! No need in wondering if the load or primer needs changing!
In addition, when I have had a rifle that shot well jumping the bullet .100 or more, that rifle would suddenly go hay wire for no apparent reason, I class these rifles as Bi polar rifles...they get a new barrel first time I find that the load goes hay wire.
In all of the many guns custom and factory that I have owned, 5 guns or less did not like the bullets seated closer than 0.010 off the lands to jammed .030. One of those guns that liked the bullet to jump .040 is a Rem 25/06, Ruger 270, and 308's are all throated long.
I have used two systems to establish seating depth, the stony point(hornady now) with stony point (hornady) ogive gages and a split neck system(slice the neck to about .050 into the shoulder with a thin dremel cut off wheel). You insert the bullet into the case neck, close bolt, bullet will be pushed back in the case. You can use the stony point ogive gage or the Davidson ogive gage($12). With either system, you will have a learning curve.
I work up all my loads with the bullet just barrely touching the lands. Once the most accurate load is established, then start playing with seating depth, then primer. With most rifles, groups below 1/2" are attained quickly.
There is an old wives tale about having the bullet seated in the neck a caliber's depth...hog wash. If you want to get the bullet started straigh in the barrel, eliminate bullet jump...every benchrest shooter knows this.
Eliminating bullet jump is very difficult these days with the attitude that if a guy can not shoot a poly tip bullet or a VLD bullet, they can't kill anything. In many rifles that have a long leade, a Semi point bullet from sierra will establish extreme accuracy quickly. Sierra 50 and 55g Semi point bullets in 22 Caliber are nearly as accurate as Berger bullets, hard to tell the difference in accuracy in my custom BR rifles.
Reloading is a hobby in and of it's self. You can take this hobby to some very interesting depths. General rules of thumb are very tough, but the things that I have stated above are pretty much the same rules that have been around in benchrest shooting for many, many years.
Each rifle is unique in and of itself. As I stated above, it is very rare to find a rifle that shoots extremely tiny groups(a single bullet hole is just enlarged) by jumping bullets. There are exceptions to everything, but getting the bullets within 0.010 of the lands or jamming the lands for best accuracy holds almost universally true with all benchrest rifles and varmint rifles in 17, 22, and 6mm & 7mm calibers.
For example, Saturday I took a Ruger Stainless in 270 and I wanted to work up a load for the 110g Barnes tripple shock and the Sierra 110g Pro hunter. I knew from past experience that this rifle was one of those rare witches that loved about .040 bullet jump. I started off with .050 bullet jump on the Barnes tripple shock, using win 760, and win primers. I started shooting 3 shot groups. At 58.0g, I was shooting 1/2" three shot groups at 100, switched to 200 which equaled 1" groups. Next, the 110g Sierra's. Used the same load with .040 jump bullet seating depth, shot a .395 group at 100, and a .786 at 200. I next played with CCI250 and Fed 215 primers...things got worse...I called her done.
It is important to know how far the bullet likes to jump, touching the lands, or jammed the lands in a particular rifle so you can keep up with the leade growth over time...you simply "chase" the lands.
20 years ago a rifle that would shoot 1"groups was the cat's meow...not so any more. Shooters demand more and more of their rifles and their reloads. Along those lines, I want to mention that very suttle wind of 5mph will open a group up to over an inch if there is a "switch" from left to right. I had the unfortunate experience of wearing out 4 barrels before I learned of wind flags, they cost about $45-$65 and are one of the best investments that a serious reloader/shooter could have.
Using wind flags are pretty simple, left and right winds, go home and don't fire a shot if the wind is blowing in your face. If you have fired two shots with the wind blowing to the right, then the wind starts blowing to the left and the shot goes to the left, you know it was the wind, not your load! No need in wondering if the load or primer needs changing!
In addition, when I have had a rifle that shot well jumping the bullet .100 or more, that rifle would suddenly go hay wire for no apparent reason, I class these rifles as Bi polar rifles...they get a new barrel first time I find that the load goes hay wire.
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