Help a gal with load development-seating depth

[Mram10us]

Seems like girls get helped pretty quick on here, so it can't hurt

Load development for powder charge works great for me, but I have never perfected my seating depth development. Aka, I don't want to do a range from lands to .100 off in .001" increments. I normally start .005" off. And go in .030" to find a rough area. Some have said that is waaaay too much. What increments do you start with? Please post pics with group differences based on depth!

 

[codyadams]

Seems like girls get helped pretty quick on here, so it can't hurt

Load development for powder charge works great for me, but I have never perfected my seating depth development. Aka, I don't want to do a range from lands to .100 off in .001" increments. I normally start .005" off. And go in .030" to find a rough area. Some have said that is waaaay too much. What increments do you start with? Please post pics with group differences based on depth!

I do the same thing, start between .005" and .010" off, and go in .030" increments. Once you have the best one, finish out your powder charge and primer choices, then fine tune your depth by going up and down in .005" increments, until I find the best one. You can fine tune from there in .001" increments, but I have always had good enough accuracy that it wasn't necessary.

 

[30calyooper]

Cody's advice is spot on.

The other and sometimes simpler method (but often not quite as precise) is to simply use the COAL listed in the reloading manual, tweak to find the best powder charge weight for accuracy with your chosen combo of brass-primer-powder, then play with seating depth in .010" increments. The catch with this method is that as you move the bullet outward (longer COAL) you have to watch two things -
1) be sure it fits in your magazine; and
2) as the bullet moves out, you may notice a tendency to see the velocity drop. If it's not significant and the accuracy is improving, then you're gaining. But obviously, DO NOT take it out to the point that you begin to experience difficulty closing the bolt. (I know, sounds pretty obvious, but I'm surprised by how many people relatively new to handloading have walked past this important point then wondered why they were experiencing pressure spikes...)

Now you may already have experienced this - but as you move the bullet outward and create more space in the combustion chamber and see a drop in velocity as described above, you may find yourself considering the the idea of raising the powder charge by a slight increment such as 0.1 grain. That's okay if you're CAREFULLY watching for pressure signs, but it may also set you back to square one as you've now altered your recipe.

 

[Mram10us]

I like to seat near the lands during powder testing for pressure reasons. I never use listed coal because I always shoot long bullets and mag length is never a problem for me.

Good point about rechecking powder after finding seating depth. Some guys start with seating depth and a moderate charge to find it first. Tried this once. Seemed to work fine

 

[codyadams]

I like to seat near the lands during powder testing for pressure reasons. I never use listed coal because I always shoot long bullets and mag length is never a problem for me.

Good point about rechecking powder after finding seating depth. Some guys start with seating depth and a moderate charge to find it first. Tried this once. Seemed to work fine

That is what I do. My load developement for best precision goes something like this.....

Coarse max pressure test:
1 round at each charge, usually moving up in 1 grain increments, half grain if case capacity is under 45 grains or so. I load up to where I know I should be over max with my high load, and plan on bulling a bullet or two. This is only to find my max pressure, and I document my velocity. Takes less than 10 rounds generally, even with wildcat or unknown recipes to find max. Usually done seated .010" off.

Coarse seating depth:
As stated, essentially the "Berger" seating depth test, from .010" off out to .130" off. Done with a load well below max, with no reguard to where nodes are or may be, seating depth should be a big enough difference to tell even outside of the nodes. Once I do my fine seating depth test, this seating depth from the lands will remain the same for this bullet for the life of the barrel, reguardless of other changes in the load.

Primer testing:
Using what I know so far, I load a safe charge at the seating depth I just chose, and figure out which primer gives best accuracy/e.s. of the different primers I have to work with.

Ladder testing/fine pressure test:
Referencing my course max pressure work up, I load up 1 or 2 rounds per charge in .2 or .3 grain increments in the velocity/pressure range I want to be in, usually going across 2-3 grains depending on case capacity. I set up a tall target at 500-600 yards, and shoot my rounds, documenting the impacts. The results of the ladder test tell me where my best load is going to be.

Fine seating depth test:
Depending on what your seeing and your expectations/requirements you may not need to do this part, but using my info I have gathered thus far, I go up and down in .005" increments, up and down .020" covering a range of .040". I shoot for groups and pick the best one.

After this, I am done. I tweak these depending on many things, but if I want the most possible out of a rifle, this is the route I go.

 

[stljc2]

Go to Berger Bullets site. I think they have recommendations on where to start seating testing....Yes I know some Berger bullets are finnicky on just where the bullets are seated. Hence the reason they have a recommendation on where to start. I start most mine about 10 thou off the lands (CBTO) and go from there. Good luck and WELCOME.

 

[Mram10us]

thanks guys. A couple serious competitors said .005" in seating depth makes a huge difference for the coarse adjustment then go down to .001". Cant argue with some of them because I know their credentials and they live this stuff. Just trying to save time and reloading comps

 

[Mikecr]

Similar to Cody
Berger's increment for coarse seating. Then after powder development, fine seating tweaking to shape grouping. This final tweak is .001" increments, within a 10thou window, as seating windows should not exceed that. Mine haven't.

 

[Mram10us]

Similar to Cody
Berger's increment for coarse seating. Then after powder development, fine seating tweaking to shape grouping. This final tweak is .001" increments, within a 10thou window, as seating windows should not exceed that. Mine haven't.

How many rounds are you using to find a load then? Seems like 3 round groups of .001" seating depth alone is .... carry the 2 ... 30 rounds

 

[stljc2]

thanks guys. A couple serious competitors said .005" in seating depth makes a huge difference for the coarse adjustment then go down to .001". Cant argue with some of them because I know their credentials and they live this stuff. Just trying to save time and reloading comps

Yeah they may be ok for their fine tned rifles but I started at a jamb once in 308 and didn't even get thru all my powder charges before encountering pressure signs. Thus the reason I start at 10 thou off the lands and work carefully both ways. Most I have seated in my 308 was 40 thou off the lands and ended up with whats below. Granted it's only 100 yds but it's a start. 3 shot group, 168 gr Berger VLD hunting, Lapua brass, WLR primers, V V N550, Sd .6, Es .8 Ave ft/s arounf 2750. Sorry for the edit...wrong number on the powder.

 

[ShtrRdy]

Dude, you're cracking me up. Oh, I guess I better read the rest of you're post.

 

[Mikecr]

How many rounds are you using to find a load then? Seems like 3 round groups of .001" seating depth alone is .... carry the 2 ... 30 rounds

For me, finding the most accurate load for a new/unknown system takes as long as it takes. You could be shocked about all the additional things I do before/during/after that described so far.

Hunting is more fun of course. If I could just cut a few checks and go hunting when I like, I would spend a lot more time doing that. But I don't get to where I live.
Oh well, load up some ammo & tinker & test & have fun at the range.

 

[shinbone]

I am always fine tuning my load development process. Currently, I find seating depth (which I call "jump" since it is also how far the bullet moves or "jumps" before hitting the lands) before doing any powder charge testing for a particular bullet. I shoot 2-shot groups to find a rough seating depth to then do the powder charge tests. Then, once optimum powder charge is found, I fine-tune the seating depth using 3-shot and 5-shot groups.

Some example of seating depth test results:

.300WSM



.223 Rem

 

[Mram10us]

Love the graphs!