I am trying to minimize my group size by seating my bullets the optimum distance from the "lands" of the rifling with my 308 Win rifles. I am using a Redding Competition bullet seating die. I need good advice on whether I must seat bullets to a depth of at least one caliber diameter as I have been advised. For the 165-175 grain boatails bullets I am using, this means they are seated much deeper than the .010 to .040 inch off the "lands" as I would like to attempt. I am using the Stoney Point OAL guage and bullet comparator inserts for my caliper to measure, and a RCBS Precision Mic. Any advice would be much appreciated.

I start at .005 off the lands and work out in .005 increments.I'v never heard of the 'caliber diameter depth "method.
Jeff

I've heard of trying to seat the bullets to at least one caliber depth into the case. I have a NEF BreakOpen .308 that has an extremely long throat that with factry ammo it's group is 4-5". For first attempt at loading for this rifle was using Nosler 165gr Ballistic Tips and seating them to .010 off the lands. The bullet was only being held my about 1/8" of the case mouth and the OAL was 3.072" which is far beyond the max OAL for .308 Win. First trip to the range yielded a 1-1.5" group varying the charge of H380. I was very impressed for this little rifle. I still want to do some more but it's sooooo hot outside I was dripping wet when I went to the range and it was extremely hard to concentrate.

Brandon

I have a .270 that likes to be about .010 into the lands using Stoney Point tools to measure. It produces groups near 1 inch at 100 yds. using 130 gr. Sierra boat tails. This is a very mild load that shows no adverse signs of pressure. As you know, into or close to the lands raises pressure so you want to work up to a load like this with caution.

The concept of using one caliber seating depth is the idea. However, what shoots best is what really counts.
Ron

Personally, I hold that the "close to the lands" mantra of reloaders is greatly overstated. It is probably easier to find an accurate load there, but in my admittedly limited experience, you can find loads virtually as accurate when seated away from the lands.

If you single load, and shoot shorter ranges, there really isn't a good reason not to sit close to the lands. However, if you are shooting long range, consistent neck tension is critically important in achieving low shot-to-shot velocity deviations. Further, if you are competing and/or loading from the magazine, plenty of hold on the bullet is vital. Short seated bullets are easy to knock out of round, and then there is hell to pay. Either case, I'd start seated deep enough to prevent those problems. JMO, Dutch.

I must have had a case of dyslexia last nite regarding 'one caliber diameter seating'.It is the rule of thumb.But if you want to get closer and don't have enough bullet,why don't you try a longer bullet that will allow you to?
Jeff

Until the 300WM came along, the conventional wisdom was that the neck of a cartridge should at least equal in length the calibre of the bullet being loaded. It was felt that was needed to properly support the bullet. We know now that is not all of the truth. As Dutch pointed out, too many folks grab one small piece of the accurate reloading puzzle and try to make it the entire picture. I think it was said best in a old Hornady reloading book I have: "Each rifle is a law unto itself and generalizations should be made with circumspection."

For one my rifles, a 300RUM, I found that you can get great groups loading out, even without one caliber into the neck. But my groups started dropping off. I was using the same brass with 3 firings. I notice with new brass, it did good, but the neck tension dropped off the more I fired it, and had to load deeper.

So after all that, I finally decided on not loading the brass that has been fired three times. Maybe anneal later. And also try to concentrate on loading to my max COL where it fits in the magizine which is 3.63". And not worring about getting to the lands.

So I believe that neck tension is important sometimes.

Huck,
Seating into the lands guarantees that the bullet starts its path down the bore straight, without deforming or swaging one side of a bullet that's off center from the axis of the bore. The closer you get to the lands, the less you worry about that problem, but the more you have to worry about initial pressure spikes before the bullet moves down the bore. I seat bullets into the lands on my 20BR, but the additional starting pressure must be considered when loading that way. My hunting rifles all start at least .010-.015" off the lands, but every load has a sweet spot for seating depth if your rifle is accurate enough to bring out the difference. I don't worry so much about the one caliber seating depth rule. I normally leave enough of the neck unsized to enable the rearmost portion of the neck to center in the neck of the chamber.
It's more important to make sure that the loaded cartridge is concentric, with uniform neck tension on the bullet. Uniform case lengths assure the same amount of linear grip of the case neck. A concentricity gauge verifies case neck runout and bullet runout. Culling out cases that vary in neck wall thickness makes neck tension more uniform and makes concentricity easier to attain. All the little things we do to improve accuracy help only minutely, but can have a cumulitive affect when we employ several of them.

Huck,

I prefer to start my accuracy teasting with the bullet just off the lands. Since I work loads up in half grain steps, any concern about pressures is elimenated. Pressures are however a very real concern if you take someone elses loads and seat the bullet to the lands because you are dealing in unknowns. What may just be a warm load in my rifle may be an action bender in your rifle.

I'd suggest that the first thing you do is to determine the length limitations of your rifle magazine. The various rifles in .308 Win usually have a short magazine that limits OAL to 2.830". This length usually doesn't allow for seating the bullet to the lands. If your rifle will allow for a longer OAL, the bullet just off the lands is a pretty good place to start. I like to smoke a dummy cartridge and use it to adjust seating depth. It seems as if the best accuracy comes with the lands touching the soot on the bullet, without touching the bullet it self.

The old theory about seating a bullet one caliber deep into a case has been explained to me as an attempt to insure the bullet will not move in the caseneck during recoil. If you are shooting one round in the rifle at a time seat them any depth you want. If you're loading multiple rounds and feeding from the magazine, your going to have to find out if your bullets are moving and correct if necessary. By the way, the theory is a good one. I hope that this is of some help. Have a good week end.