My 300 Win Mag shoots the 200 grain Nosler Partition best at 0.030� off the lands. I have tried 0.015 through 0.040� off and 0.030 was most accurate and is quite good (1.7� groups at 250 yards). None of the other seating depths tried were acceptable. Unfortunately my magazine box is too short for the cartridge loaded at that length. So I wonder if I could maybe find another sweet spot with the bullet seated deeper. Should I bother trying loads with the bullet seated deeper? If so what would you recommend for seating depth increments? Should I go in 0.010� or 0.020� or 0.040� increments initially or what? My box length is 3.6� long. I know that many 300 Win Mags have boxes only 3.38� long or so and yet presumably people can get them shooting well with a standard chamber (which would give them about 0.220� jump to the lands). Any suggestions? Thanks, Rufous.

I would start at the longest seating allowed by the magazine and move back in 0.010" increments to see if you can find a sweet spot...watch out for pressure signs as you will decreasing the size of the combustion chamber of your powder.

You may have to tinker with different powders and primers to get what you want...if you can.

Knowing the brand/model of your rifle would help things a bit.

Remington and some others provide a lot of "free bore" in their rifles so that handloaders don't "screw up" and seat bullets against the lands. As a result, most loads with good bullet seating won't fit in the magazine of the gun.

My solution to the problem was to take my barrel, set-back the chamber and rebore to .223 Ackley Improved. Now I get bullets seated where I want them. They fit in the magazine. The case necks have plenty of bullet to provide even neck tension, and I'm a happy camper.

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.223 Ackley Improved Wildcat Forum:
http://www.hotboards.com/plus/plus.mirage?who=223ackleyimproved

rufous-

If this is a hunting rifle (and being a 300 WM I'm betting it is), you may need to sacrifice gilt-edge accuracy for practicality. Having a rifle that will only hold one round (in the chamber), isn't the best bet for hunting. If you're gonna settle for that, you might as well get a nice Ruger #1. Start at the longest length that will fit in your magazine, take off a hair just in case you get a long bullet, and experiment back from there. You will find where it shoots best within the magazine limitations, and will have to accept that.

Of course, you can start the whole process over with a different bullet, etc.

Rufous, If it were mine I would find a length with a dummy round that feeds well from the mag, then I would adjust in .015" increments shorter. Once you find the next sweet spot try a few .005" in both directions from there for fine tuning. As posted earlier watch for pressure signs.
Dave

I received an email a while back regarding my OCW load development method. It was from Gerard Schultz of GS Custom bullets... I hope he won't mind me referring to it here:

Hello Dan,
Your method of load development is right on the money. I have designed 140 new bullets and developed optimal loads with them in even more calibres over the last 9 years and this method is the only way to go. Tuning a group by varying the load is a waste of time and components. If the col for a rifle is optimised, speed variations are of lesser importance. See the page below on our website where we recommend a very similar method.

http://gunlinks.zibycom.com/members/002245268/Site2/hvloadguide.html

Regards
Gerard

Anyway, what I'm getting at is that you're right to be looking at the OAL (distance to the lands) as a *fine tuning* of your load. I believe, like Gerard does, that adjusting powder charges in search of the best load is not the best approach.

You're probably better off not starting with a preconceived notion as to what distance from the lands your rifle likes. The truth is, it probably likes a *lot* of different distances from the lands. The OAL should be the last adjustment made. Often times we decide via one device or another that our rifle really likes .015" off the lands, and then tune powder charges to make that distance work. You can just as easily back off to .025" and adjust the charge and accomplish the same thing.

Look at it like building an engine. Powder selection and charge weight is equivalent to piston (compression ratio) selection. The OAL adjustment is like adjusting the *timing* of the completed engine. Yes, you can select a particular advance in timing, and alter compression ratio, etc, to make the engine perform with that particular timing advance, but you'd be working backwards.

There is an optimal amount of powder in a given load recipe that burns most evenly and consistently. Find that charge weight by the OCW testing method or any other such method that might work for you, then *tune* your accuracy with OAL adjustments as a final step.

Best of luck in your load development,

Dan Newberry
green 788

Dan Newberry, what is this OCW testing method you are referring to? I have never heard of it. Please explain further. I had no preconcieved notions as to what seating depth the gun would like best. I started with the bullet 0.010" short of the magazine box and worked back from there. The problem is that now the throat has eroded and to have the bullet 0.030" off the lands which is where the Nosler 200 Partition shoots best in my gun (from 0.010 to 0.050 the 0.030" off was most accurate by far) the cartridge is too long for the 3.600" magazine. So it sounds like I can just keep seating deeper until I get the accuracy back. Is that right? One thing about the previous load is that the velocity was about 150 fps less than I could safely get. If I tried more powder the accuracy would drop off. So if I am reading you correctly I should increase my powder charge to get the maximum safe velocity and then start seating the bullet deeper and deeper until I get the accuracy back. Have I understood correctly? I do realize that as I seat the bullet deeper I will likely increase pressure. Thanks for your help, Rufous.