Bullet Seating Depth or Powder Charge - What First?

[sithlord6512]

Now that I got my brand new Hornady bullet seating depth gauge, I am wondering how I should proceed.

Should I find the most accurate charge using RL19 (increasing by 1 grn increments) and bullets seated to match the OAL listed in my Nosler manual First, then play with seating depth

OR

should I play with seating depth first using the most accurate load listed for RL19 in the Nosler 6 manual (it happens to be the middle load - i.e., between Min and Max). My only concern with this apporach is pressures - is is safe to start at the middle load?

Thanks in advance.

 

[Ol` Joe]

Find the OAL that places the bullet just at the lands and work up to max with it there. Once you have a max for your rifle decrease the OAL in 0.005" increments until you find the lenght your rifle prefers.
Only alter ONE thing at a time. Stay with the same primers, brass, powder and charge while doing this.

 

[old #7]

I agree with changing one thing at a time.
But, I wouldn't start at the lands. .010 off is my normal starting procedure if the mag box allows. Then adjust closer after the most accurate powder charge is found. I use coal as a fine tuning tool after a load shows promise.
I am sure you could start at listed coal to come up with a great load also.
I think one thing at a time is the key.
Of course safety first.

 

[Powerstroke]

Ditto on the above mentioned to change one item at a time.

Depending on Mfg & Caliber there are a lot of rounds out there that end up too long to go into the magazine. At that point, the magazine determines Max COAL. Unless you're ok with a single shot hunting rifle ?

Personally I never seat anything in the lands.... depending on bullet type also, but I start at .015 off the lands and usually don't have to deviate much from there. I'll start playing with powders first to see which one I at least get consistent results from.

 

[blacktailhunter]

As mentioned above, try different powder charges first to see what velocities you are getting, and to find the max charge in your rifle. Do this by working up in 0.5 grain increments. There should be a charge or two that show some consistency in both velocity and group size. Take those loads and adjust the COL from there.

I do not recomend starting any closer than .030" off the lands. Take the powder charge that looks promising, and adjust the COL closer by .005" and farther by .005". Continue this process until you see an improvement in groups or a noticeable opening of group size. This will tell you which way you need to work your COL. Keep in mind that in a hunting situation, any dirt, lint, grime, etc. that could get on that cartridge could make it dangerously into the lands if you are just .001" away to begin with.

It is a myth that you MUST be close to the lands in order to find accuracy. The right powder charge along with consistent load techniques will yield accurate handloads. COL is very important, but it is one of the last adjustments I make to a possible keeper load.

 

[DrMike]

Keep in mind that you are looking for two separate results--accuracy and standard deviation. While there is a correlation, it is not strict. Accuracy in a load is generally what we look for and is measured by group size. The standard deviation of a load (consistency), refers to the measured velocities. All else being equal, a consistent load can be made to shoot accurately. However, not all accurate loads have great consistency. The rifle itself and the components play a significant role in that particular determination.

That being said, if you have a load that shows good consistency, you may want to play with seating depth to improve accuracy. As others have suggested, set your bullet at a standard distance from the lands at first and measure your velocities with a given set of loads. If a load shows promise, then you might wish to change seating depth.

Again, as has been mentioned, while it is often true that the closer to the lands the greater the accuracy, this is not a hard and fast rule. With monolithic bullets, a growing number of reports indicate that a large jump to the lands improves accuracy.

 

[bullet]

I agree with changing one thing at a time.
But, I wouldn't start at the lands. .010 off is my normal starting procedure if the mag box allows. Then adjust closer after the most accurate powder charge is found. I use coal as a fine tuning tool after a load shows promise.
I am sure you could start at listed coal to come up with a great load also.
I think one thing at a time is the key.
Of course safety first.

Yes, I would not start at the lands, mag box will determine where to start then if your group and chrony show promise you can play with OAL.

Also DrMike has summarized the issue very well.

 

[ted1]

i already had an accurate charge worked up when i bought the OAL gauge. measured to the lands and backed off .040. This was 1.25 longer than b/4. Expecting super accuracy was disapointed to find that accuracy got worse. As this creates a larger void between powder and the seated bullet do you think this might be the culprit? 270,47.5 IMR 4831 150 grain Nosler BT COL 3.520 (b/4-3.355)

 

[FOTIS]

Up and down with the power then fine tune with the seating.

 

[JD338]

I agree with the others. Start is a known seating depth and work with the powder charge first. Then you can fine tune with the seating depth.

JD338

 

[RiverRider]

I discussed a theory with my handloading mentor years ago regarding this, and we decided that it might be effective to select the powder charge by chronographing and going with the charge that yields the most consistent velocity, and then tuning for accuracy via COAL. We never did test the idea. I have no idea whether it would be an effective approach.