A recent thread got me thinking about a related issue.

I understand that most rifles have a definate preferance when it comes to how far the bullet is seated off the lands. I've read that this usually falls in the .015 - .035 range, deeper with all copper bullets.

How do you go about finding the "sweet spot?" What depth do you start at? What increments do you use between different loads for comparisson (i.e. if your first load is .015, would the next be .020?) Assuming I don't contact the lands, will these changes in seating depth alter chamber pressures?

belaw:
When working up a new load, I usually begin with bullets seated to the depth recommended in the books and I vary the powder charge. I use a chrono and write each bullet impact on the target along with the velocity. I usually start at the "accurate" powder charge listed in the book and work up & down in 1/2 gr. increments. My bullet seating is ALWAYS measured to the ogive and not OAL. Once I've found the most accurate/consistant powder charge, I begin playing with seating depth and make changes from the original in 0.005" increments. Since I never work with max. powder charges, I've never noted severe increases in pressure however I do look for them. Now, I nominally end up seating bullets to approx. 0.010" off the lands. Even though this is relatively close, I've never had chambering problems but I always run each round thru the chamber to verify good feeding. My rifles are for hunting & I don't want to take any chances of a misfeed.
Guess I'm quite anal about it but I always use a competition seating die and check each cartridge for proper depth. The use of an electronic caliper makes the procedure a piece of cake. Hope this helps some.
Bear in Fairbanks

I usually start with seating the bullets a half turn of the seating stem off the rifleing. I seldom have to do anything else. I feel powder charge has more effect on finding the sweet spot. Some cartridges like the 308 I will seat say a 150 grain Speer flat base even with the shoulder neck junction as long as the bullet is not up against the rifling. My present 308 shoots best with flat base bullets seated like that.

I start with the bullet at the rifling and work up my load. I then start backing off in .005" increments until I find the sweet spot.

Belaw;I reload for two calbers,may be I got two "sloopy chambers"but the best accuracy I can get is below the C.O.L recommended by the reloading manuals,always near the lands with a hunting rifle,that make me thinking about what difference it will make...

I use a variant of Ol'Joe. I start with one charge and vary seating depths, starting just shy of the rifling. 99% of the time, one OAL shoots a tighter 5 shot group than the others. I'll keep said OAL and then work on the charge. I've found this procedure quicker than going the other way around.

I had the same question a few years ago. I asked a friend of mine that is an ex benchrest shooter. He said that the less bullet jump the more accurate you will be. He believes that your bullet should be seated in the lands. I don't believe a bullet should in the lands. I do believe that if you stay .005 off the lands and you work your powder charge up and down from there, you will find the"sweet spot" that you are looking for.You do need to watch out for how deep the bullet is in the neck of you case. Say if you are shooting a 223 and using a 35 or 40 gr bullet, you may not be able to seat your bullet .005 off the lands like you would be able to a 50 or 55 gr bullet. A 35 or 40 gr bullet will not seat very deep in the case neck if you try and seat them .005 of the lands, and this has created a new set of issues for me when trying to use light bullets.

As for changes in chamber pressure, yes there will be changes. SO WORK YOUR LOAD UP SLOWLY!

I hope this helps and good shooting.

You can't stay .005" off the lands consistently.

Unless you make your own bullets, you'll find that a box of factory stuff contains projectiles with varrying diameters and ogjives. There is no way to keep the loaded rounds at .005" off the lands. You'll have to find the bullet with the longest ogjive and use that as a benchmark. But your next box of bullets will be different still.

If you want to load into the lands, then use light neck tension and seat the bullets way long. Otherwise, keep them at least .025" back. If you try the .005" method, some will be touching the lands, some will be jammed in the lands, and some will be more than .005" away from the lands.

I buy all my bullets in bulk and sort them. Then re-box them according to Ogive length. I don't sleep very much so I have a lot of free time on my hands early in the morning.

how do you measure ogive on individual bullets?

With a bullet comparator.

I use a Stoney Point chamber-all bullet comparator, and a Dial Caliper. I don't use a case with this setup, just the bullet's when I'm checking bullets. This way it is a two in one tool.

You can pm me if you need help?

Thanks, But I was just curious, I don't think I will ever seat anything within about .025"

If your hunting it's almost a non-issue.
If your target shooting, it's one of those small issues that you try to watch.

I've heard a few people swear that their rifle shoots best if loaded to the lands but a lot more people will agree that this increases chamber pressure and can lead to difficult to load shells.

One manufacturer was reported to leave a large distance from the oglive to the lands and still give very good accuracy, though more of a hunting accuracy.

Seating into the lands is more of an alignment issue.

If you have a loose throat diameter, then seating in to the lands helps to center the bullet in the bore, provided that your run out is minimal.

If you have a tight throat, like .0002" over bullet diameter, then seating into the lands only offers the benefits of a tight crimp. The problem is that the lands move further away from your bullet with every shot (erosion). So, your OAL will need to change periodically depending on the round you use.

While I don't claim to be a reloading expert, I think that the distance off of the lands may be of little consequence compared to other factors, such as load/muzzle velocity. I have worked up a very accurate load in 7 Rem Mag and another in .22-250 (Both factory Savage rifles) and load both to the OAL recommended in the Hornady manuals. Both consistently hover around half-inch 5 shot groups when I do my part (100 yards, of course). Like Ralph said, when you begin concerning yourself with being .005" off of the lands and similarly precise measurements, you have to be religious about measuring the actual length from the ogive and repeatedly checking for change in throat length due to erosion.

Tim

No matter what your COL is, you will get throat erosion. You will also have chamber pressure to deal with no matter what your COL is. I get 15 plus loads out of my 223 AI, and 22-250 with the way I reload. Most of my friends that I shoot with are not happy if the shoot over .300 at 100 yards. I also load 7 mm Rem mag, 300 Win mag, and 338 Win mag, and get good brass life as well. These I load for magazine length.

Depends on a lot of things. Mostly if you plan to go single shot or use the magazine, type of bullet and grain. The old "gotta be resting on the rifling or so many thousands from them can be thrown out of the window on many rifles. In order to use the magazene on my 7.7 the 180 grain bullet must be .085 from the rifling and it shots .375 groups all day. Give the rifle what it wants and in some cases needs. I you can start resting against the rifling have at it, but this "gotta be this or that does not apply in a big bunch of rilfes that shoot real accrute.

quote:

Originally posted by Ralph Hyrlik:
You can't stay .005" off the lands consistently.

Unless you make your own bullets, you'll find that a box of factory stuff contains projectiles with varrying diameters and ogjives. There is no way to keep the loaded rounds at .005" off the lands. You'll have to find the bullet with the longest ogjive and use that as a benchmark. But your next box of bullets will be different still.

If you want to load into the lands, then use light neck tension and seat the bullets way long. Otherwise, keep them at least .025" back. If you try the .005" method, some will be touching the lands, some will be jammed in the lands, and some will be more than .005" away from the lands.

Huh?????

Here is some seating depth information from Nosler

quote:

quote:
Originally posted by Ralph Hyrlik:
You can't stay .005" off the lands consistently.

Unless you make your own bullets, you'll find that a box of factory stuff contains projectiles with varrying diameters and ogjives. There is no way to keep the loaded rounds at .005" off the lands. You'll have to find the bullet with the longest ogjive and use that as a benchmark. But your next box of bullets will be different still.

If you want to load into the lands, then use light neck tension and seat the bullets way long. Otherwise, keep them at least .025" back. If you try the .005" method, some will be touching the lands, some will be jammed in the lands, and some will be more than .005" away from the lands.


Huh?????

douglast, got me wondering too.

Ralph are you measureing off the bullet tip or ogive? I agree the COL will vary a lot if measureing off the tip, but the OAL to the ogive should still be very close . I use a Stoney Point to measure my loads and if I`m off more then +/- .001" in lenght it`s something I did, not the bullet at fault. The seater should work off the ogive and seating is normally very precise.