It is amazing the differance in statements about bullet depth so someone who knows enlighten me a bit. In the past I have loaded mostly bullets that have the cripming groove and seat them to the middle of the groove. And those that didn't I would seat them to the bottom of the neck. This worked real good but now I am working to get better groups. With some 180 grain spitzers I chambered a dummy round pushing the bullet against the riflings. I keep reading that if you start there chamber pressures can rise fast and maybe over pressure so seat the bullet another .005 to .065. Other articles state that is a good place to start. Some of you experienced folks steer me the right way to go on this.

First of all, unless you need to crimp (highly unlikely except for tubular magazines and some automatics) ignore the crimping cannelure on the bullet. Better yet, look for bullets without a crimping cannelure, as there is nothing good that a cannelure can do for accuracy (look at some high speed shadowgraphs of bullets in flight and note the the cannelure creates a shock wave all its own).

The advice to start with the ogive just touching the lands, then back off a few thousandths, is generally good advice. With some calibers, chambers, and magazines this may not be possible. Seating the bullet at this length does not assure best accuracy, but it is GENERALLY a better place to start than deep seating which requires the bullet to "jump" a distance before engaging the rifling. Sometimes (and unpredictably), deeper seating does result in improved accuracy, the theory being that seating depth changes the harmonics of the barrel vibrations, or at least can better synchronize with the barrel harmonics.

Please note that with light-weight (short) bullets, seating out to near the lands may not leave a sufficient portion of the bullet shank inside the case neck. Therefore it may be impractical to seat short bullets "to the lands".

Although some gun writers have advocated varying seating depth as a way of tuning rifle accuracy, I'm afraid that you could burn up a barrel with the volume of ammunition that it would require to prove out the most accurate combination. And if you were switching things like primers, varying powder weight, and trying different makes of brass, I can assure you that you would never be able to have the time, patience, or money to thoroughly test all of the variables (much less have it mean anything, since by then you'd need to start over with a new barrel

At any rate, the caution against seating with the bullet hard against the lands is based on the theory that the higher initial resistance to forward movement caused by bearing against the lands creates a quicker, and undesireable, rise in chamber pressure. Ummmm . . . maybe, or maybe not, but still, seating against the lands is not a good practice in that the bullet may become lodged in the barrel or moved when attempting to eject an unfired cartridge.

Hope this helps.

It depends, in my experience (with well over 100 different sporting rifles) is that every rifle/load has a preference or "sweet spot". Sometimes it is very close to the lands, other times it is amazingly far from the lands. Case in point, I currently have an 8x57 that shoot sub 0.5MOA with 180 Nosler BT and (yes) 185 Rem PSPCL, yet both are seated a LONG way from lands. Seating the bullets closer to the lands actually HURTS accuracy.

For bullets with cannelures, I often start by seating the bullets to that point (assuming I have mag room and throatl/leade room). I then work forward from there as necessary. I start there because, if it works at that seating depth, the round will look good. Say what you will, but bullets seated with their cannelure showing just ain't that pretty.

Now for target rifles, which are usually put together with more excating tolerances, you can expect a near perfect chamber, tight neck, bores, etc. In these circumstances, about the only "wiggle room" for the bullet to begin a yawn is during the jump from neck to land. Thus, I'd suspect that seating near to or just touching the lands may be optimal more often with these types of rifles. Just a conjecture...

So I'm curious: Say you've found the "sweet spot". How many thousandths off from that length will it take to make a noticable difference?

My experiments with this parameter never seemed to make a discernable difference. Perhaps I was changing the depth too much, or not enough.

many thanks for the info. I never crimp any rounds as I don't load an auto loader but I did use the crimp ring as a guide at times. On my .41 magnum rifle I set one against the rifling and went a few thousands .031 to be exact deeper. Understand how all rifles are looking for a certian combo to work well. with my ole 7.7 Jap that I am getting ready to test this week I don't expect 1/4 inch groups but would like to see what I can do with it and what makes it work the best, well-that is what reloading is all about anyway. I think I will go .005 from the rifling and go from there. I will be trying three different type primers, two different cases and two different powder loads and go from there. And Stonecreek you are right about a bullet getting stuck in the barrel. Seen a person do that no long a go with a small 110 grain 30 caliber bullet. They had a time getting it out. So will back if off a bit and go from there. Thanks again!

If a rifle is highly sensitive / responsive to oal tuning, there is usually something less than perfect with it. There may be concentricity issues or stresses on the barrel or action.

I have found it useful to do one thing at a time with load development. First find the speed you want and then tune the oal. When experimenting with primers or different powders and charge weights, make one change at a time and document it.

Any other system will produce no result to speak of other than driving you nuts.

Well as I should have known I would have to consider the finished round going into the mag. I had to back of to 0.85 from the rifling to get the round to go into the mag and work well when bringing the next round into the chamber. But at 0.85 the group was 1/2 inch at 100 yards.

It also depends on the (kind) of bullet and rifle you're using. Monolithic bullets like Barnes X seem to shoot best with a "jump" to the lands. Their instructions call for seating the bullet approx. .050 off lands to start, not up close, to minimize the effects of pressure spikes caused by close seating. Weatherby uses the same technique in their hot magnum chamberings with their long throat.