Seating depth or charge weight? Which is primary?

[flopduster]

I am working on a new load for my rifle. I have selected berger 155 hunting vlds and am using r-15.

After researching about loading vlds and reading the berger bulletin about them, I selected a near max powder charge of 46.0 grains, then loaded some work up single rounds in half grain increments to make sure pressures were ok. Berger recommends loading 6 rounds each at .010, .040, .080, and .120 off the lands, and firing two three shot groups looking for one set that is much better than the others. I have so far tried the .010, and .040 off loads with poor results. Next I will try the .080 and .120 loads.

My question: after finding a good seating depth for my rifle, will I then be able to change my powder charge(increase) without having to search for a new seating depth? Will that seating depth be optimal for that bullet under most brass/primer/charge weight combos?

 

[ChadTRG42]

Re: Seating depth or charge weight? Which is primary?

This is a very detailed question, and lots of opinions and techniques to try. But, changing your seating depth and keeping the same powder charge can take a good load and make it not shoot as well. When I say not shoot as well, I also include an increase in your extreme spread between rounds. So, I think they are both important. The VLD's typically shoot best right on the lands. So, I would seat the bullet out as far as possible to the lands as magazine length will allow, and work on your powder charge. If you can not get it to shoot with it on the lands and changing the powder charge .2 or .3 grains at a time, then work on the seating depth. Most rifles will shoot well with the bullet seated out further than book max COAL. My .02.

Chad

 

[flopduster]

Re: Seating depth or charge weight? Which is primary?

I can put them on the lands if necessary, and still fit mag. 2.900 is touching. The loads i fired this am were at 2.890 and 2.860. Maybe for my next test I should try 2.900 and 2.830 so as to not abandon the berger test recommendation but give kissing the lands a try also. As this is a hunting gun, I prefer no jam.

Then maybe take the best of these four seating depths and then work with the powder charge. I realize that some 1/10 tw dont like the 155s. I had finally got my 168 nbt to 1/2 moa, hoping to find something better.

 

[ChadTRG42]

Re: Seating depth or charge weight? Which is primary?

Are you only loading 46.0 grains of powder? You really need to play with the powder charge. Because you can not get a bad powder charge to shoot well, no matter what the seating depth is. I would seat it at the 2.90 you are talking about, and vary the powder charge and see what happens. Go up in .2 or .3 grains while keeping the 2.90 seating depth. Also, the VLD's will vary by .010 on the tip. So, find a median length on seating depth for the cases without changing your die set-up. The ogive of the bullet is the important part.

 

[flopduster]

Re: Seating depth or charge weight? Which is primary?

So you recommend that I find the best powder charge and then vary seating depth, rather than finding the best seating depth and then vary the charge.

Its kind of like "which came first, the chicken or the egg"

 

[doc76251]

Re: Seating depth or charge weight? Which is primary?

In general I'll find the lands and back off .02" and begin load development. The powder charge will have the largest impact on your accuracy / repeatability / consistancy. Once I have a load that is consistant and "pretty accurate I'l futz with the load length. Generaly a .01" increase nets the most gain.

I will not seat INTO the lands for the shooting I do simply because I can't afford to have a chamber/action full of powder because the line went cold.

FWIW my best loads have been where I am "slightly" compressing the load. Generaly with enough moving around the load will settle and not be "compressed". Max case fill with a minimum of compression is a desirable destination.

Cheers,

Doc

 

[ChadTRG42]

Re: Seating depth or charge weight? Which is primary?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flopduster</div><div class="ubbcode-body">So you recommend that I find the best powder charge and then vary seating depth, rather than finding the best seating depth and then vary the charge.</div></div>
Most definitly. Or, just seat the bullet out on or just off the lands, and vary your powder charge. The thing about finding the sweet spot load on a rifle is 1 of two things. Tune the load to the rifle, or tune the rifle to the load. Almost always you have to tune the load to the rifle. If you have an adjustable muzzle brake, or barrel tuner, then you can tune the rifle to a given load. A bad load will still shoot bad at most any seating depth. If you seat the bullet out on the lands, and play with the powder charge, you should find a load it likes. If you want to fine tune the sweet spot load some, then vary the seating depth. Most bullets like to be as close to the lands as possible. That's why I start there.

 

[flopduster]

Re: Seating depth or charge weight? Which is primary?

thanks,

will load different charge weights and find best results and then mess with the seating depth.

fwiw, the loads I shot this am grouped 3/4 and 1moa for the 2.900 load, and 3/4 and 1 moa for the 2.650

 

[CoCaDoRi]

Re: Seating depth or charge weight? Which is primary?

if you are on the lands or in and then test charge weights things can go boom or get very interesting. Mallet, 4 letter words or bandages come to mind.

Take a safe seating depth, do a round robin test and then tweek.

 

[Downzero]

Re: Seating depth or charge weight? Which is primary?

I think a consistent powder charge is way more important than seating depth, although because pressure = force x area, the two are related.

 

[Wil]

Re: Seating depth or charge weight? Which is primary?

I disagree Downzero...

I think both are equally as important if you want consistency.

If your seating depth is different from round to round you will not engage the lands the same with each shot...

Both consistent powder charges and consistent seating depths you will achieve greater accuracy. Without both you will be chasing your tail.

Decide on a charge, find one that shoots well, and then think about adjusting your seating depth (altering your bullets relationship to the lands).

or... decide on a max seating depth, and alter your charge weight accordingly until you achieve the accuracy node.

one must remain constant throughout the experiment. After you have settled on which charge weight and seating depth, they both must remain consistent (jumping or jamming).

-Wil

 

[johngfoster]

Re: Seating depth or charge weight? Which is primary?

I think you will find most of us will first test for charge weight, and then play with seating depth. Not everyone does it this way, but I think most reloaders do.

 

[krw]

Re: Seating depth or charge weight? Which is primary?

Go to 6mmBR.com. There is an interesting article about the VLD's and seating depth. It talks about the seating depth and how there is a "sweet spot" away from the lands. Have never shot them but article was interesting to read. krw

 

[Nocalphoenix]

Re: Seating depth or charge weight? Which is primary?

How big of a sweet spot do most of you find? My .308 was giving vertical stringing with Varget and cleaned up into nice little clusters by adding the last .3grs.

 

[kyreloader]

Re: Seating depth or charge weight? Which is primary?


www.clik.to/optimalchargeweight

 

[308sako]

Re: Seating depth or charge weight? Which is primary?

.

 

[flopduster]

Re: Seating depth or charge weight? Which is primary?

Shot two five shots groups this am, one group at 46.3gr and the other at 46.6. 2.900coal. Both loads put 4 shots in 1/4moa with a flier opening the group to 3/4. I will repeat the test a few more times to get an average, then tweak the seating depth.

 

[ChadTRG42]

Re: Seating depth or charge weight? Which is primary?

There you go!

 

[montyb]

Re: Seating depth or charge weight? Which is primary?

my SOP is to seat to the lands and load up form 10% below max until i see pressure signs i'm comfey with. this produces positive results more often than not. i don't obsess over micro groups, and favor velocity over bench groups, esp. for hunting.