Seating depth tests

[YZ-80]

I have a Chrono but do all load development at 400 plus with out it. So I am looking at groups. Typically if I can get a repeatable 1inch or less group at 400 it will be good out to 1k, done. I will stick the chrono on after just to get a close number to put into a calculator. Tried using a chrono looking for low es and all that jive but found that the magspeed opened groups up on lighter rifles. Just what works for me

Well, if your shooting 1/4 MOA at 400 I would think your ES would be pretty decent anyway, so you don't need no stinking Magnetospeed messing up your groups!

 

[Korhil78]

Seating results and ES/SD are unrelated, until best seating hits the lands (IF best seating is in the lands).

I'm very interested in your response. Are you saying then that powder charge determines most of the load development? Because if you are saying that seating depth changes group size and powder charge changes group size and ES/SD, would it not be more constructive to do a powder charge test at a certain seating depth and when you find something close you want to work with, you then play with seating depth?

That way has always made the most sense to me but sometimes you look at your targets and start to wonder about things.

 

[Jcalloway8603]

I actually ran the Berger test on some VLDs Yesterday and today to finalize my load. I will say that it 100% worked and my rifle loved .090 off the lands. Ended up with a 1/4" group with my factory Remington 700 Long Range 7mm Mag.

 

[BrentM]

Me, I set my bullet 10-20 off the lands and work up the loads doing a velocity ladder looking a stabile and hopefully wide velocity node. Usually shooting at 300-500. Once I hone in on the upper charge weight with stabile velocity I shoot for accuracy test and verify low sd/es. If accuracy is not great I test seating depth. Again 300-500. This method has been working well for me.

Just to throw this out there....100 yard groups don't mean anything to me other than for zeroing. I have had many many bughole groups with horrible sd. I have also had outstanding 400-500 yard groups with horrible es. I shot a sub moa group with 6 charge weights and 130 plus es working on loads in my 6.5 PRC. I am of the opinion and experience that without low sd/es for long range shooting you don't have a good load. You may have load tuned for a specific range but not for a wide variety of ranges, especially when you get to 1k and beyond.

 

[Mikecr]

Are you saying then that powder charge determines most of the load development?

Yes. I call that part powder development, in that you're finding powder nodes.
It's my contention that seating is separate, different, and unrelated to load tuning.

would it not be more constructive to do a powder charge test at a certain seating depth

Yes, but at tested best coarse seating depth. Then after powder development at best coarse seating, go back to seating & tweak it in it's window for tightest group shaping. This is not tuning, it's merely tightening of grouping.
Coarse seating & primer swapping, then powder, then fine seating.

 

[emp1953]

Finding my most accurate load has always been a time consuming and somewhat costly exercise. First of all get organized. Keep everything verbosely labeled. Once the round if assembled you have no idea what's inside. (First) I load up a bunch of rounds with charge weights in 0.2gr increments, 5 rounds per increment, within some Max/Min window. I get those numbers from as many sources as possible. My experience with a given powder/caliber comes first. Suggested loads on this site come next, then recommendations from "SEVERAL" reloading manuals. This will result in several accuracy nodes being revealed. Part of this process involves cleaning the barrel every 5 shots and allowing it to cool completely. Always shooting single shot mode, never loading from the magazine. I start at 0.020 off the lands at this stage of the exercise. That's the first day or two at the range. Remember there are no shortcuts. You are only doing yourself and your rifle a disservice if you take a shortcut. Lets say you've identified two accuracy nodes, based on your 5 shot groups from those loadings. (Second) Load up a bunch of rounds with those loadings identified by your accuracy node results. I load all of those rounds .002 from the lands. Again, don't shoot from the magazine, load each round singly. I take a single stage press to the range with me, mounted on a board along with some carpenter clamps to affix it to a bench at the range. I also take a dial caliper (available from Harbor freight for $20) The seating die in the press has a micrometer adjustment for bullet seating depth, its old, from Redding, but it works. I shoot a 5 shot string, clean the rifle, let it cool. Adjust the seating die down .002 and fire the next 5 shot string. If in this process I produce a group that is extremely tight, I do 5 more at that seating depth and see if the tight group is reproducible. If it is there is no need for me to look further. I will fire one more 5 shot string, record the OAL of the cartridge using the dial caliper then I go home. Use some padding at your shoulder. Depending on the caliber this much shooting could be unpleasant for some and is one of the chief reasons people don't have the patience for the process. Food for thought -> I have a Rem model seven in .243win that I went through this process with and it didn't work. I found three accuracy nodes with the varying powder weights. The nodes weren't that spectacular, not what I expected from this rifle. Changing seating depths took me further away from the nodes. Advice from shooters on this site led me to changing powder to I4350 and start with a charge weight of 35gr. This powder made all the difference, I quickly found 3 nodes and quickly found that 0.16 off the lands gave me a 1/2" group at 100yds. The reason I keep saying that I do not load from the magazine is because sometimes a bullet will jump forward due to recoil voiding the entire process. Patience, Patience, Patience. When I get to a location where I can test my loads at longer ranges, 600-800yds, without exception these loads are within Minute of Deer which is my goal. Whitetails are my target and ranges seldom exceed 500yds.

 

[BrentM]

If anyone is burning tons of rounds and struggling to dial in a long range rifle for multiple distance engagements do this:

 

[3800fps]

In 2506 I've found that a specific load that shoots best in one gun shoots best in all my 2506s with minor seating depth tweaks....(actually ran a test years ago on a Sako Finnbear 2506 from .030, .020, .010, .005 off the lands to light touching)
The trend was clear that there is a sweet spot and moving away either way opens up the groups.
Also, I've found this to be true of the older Nosler loading manuals..when they note a most accurate load...it is just that....with a little seating depth adjustment. (note the barrel length they used)

 

[Tech4]

Berger is the only bullet I use the seating depth makes a big difference. Other bullets I use will usually shoot accurate by adjusting the powder charge without playing with seating depth too much.

 

[waveslayer]

I do pretty much the same as Korhil, I start at .010 off and work backwards.
I do all my seating depth and final powder charge test at min. 500 yards.
If I'm not getting the results I'm after then I also do a primer test.
I dont let E.S be my end all, the paper target decides it for me.

I think toy have good advice but will challenge you on a bad ES when you are talking ELR, ES will hurt your groups.

To the OP's point. Seating depth should be tested at the end because of too many variables are in play. Figure out charge weight first, then play with seating depth and primers. Using QL has helped a lot with figuring out using different powders and primers, once it is tuned, then I know my barrels harmonics based upon velocity . Then I tune from there

 

[Tiny Tim]

Last couple of rifles I have done load development for, I have used the Berger method. In all fairness, I was shooting Berger bullets. It worked well for me, but I'm not chasing bugholes yet. I do the coarse seating depth shooting at 100 yards and powder development at 300 yards minimum. Final seating depth to follow. Coarse seating depth changes after powder development can potentially change pressure and move you out of a node, or even be dangerous at maximum loads. No expert, but has worked on these two rifles, quickly attaining an honest .5-.6 moa load with precious little barrel wear.

 

[Savage 12BVSS]

Yes, but at tested best coarse seating depth. Then after powder development at best coarse seating, go back to seating & tweak it in it's window for tightest group shaping. This is not tuning, it's merely tightening of grouping.
Coarse seating & primer swapping, then powder, then fine seating.

This is exactly how I do it for every cartridge I have built a load for, I've never had a load I needed more than .030 off usually less. I start with coarse ( I like that term for it) and then work up the sweet spot powder charge, then I primer tune and have found a lot of loaders seem to ignore this step, then I really fine tune the seating depth till it tightens up that last bit. Takes a while but its worth it, the throat will slowly erode with barrel life and will need to be reset to original distance off. Brass prep and concentricity tuning completes the load. Dave

 

[Littlehud]

Years ago I purchased a Remington 700 ADL 22.250. I got the ADL specifically because it was cheap, had a light barrel and I wanted to learn how to tune a rifle for accuracy. First thing I did was free float the barrel, and bedded the action. I then lapped the action, and started trying different loads. This gun was a disaster. The best I could get with it was 6" groups no matter what I tried for charge weight. I actually missed a rather large rock chuck at 75 yds. or less 5 times with factory ammo!
I finally settled on the charge that gave me the "roundest" grouping and started with bullet seating depth. Once I found the right depth that the gun liked, the groups went down to .25 inches CONSISTENTLY! If I changed that depth by .005" I was out to 6" groups. I actually liked the gun after that, but decided it was way to picky to load for, and factory ammo didn't shoot worth crap, so I sold it. I did tell the person buying the gun about this issue, and gave him loaded rounds to copy and he was fine with it. Seems to me that bullet seating depth is more important than charge weight, so I suggest you start there.

 

[Mikecr]

Seating is a COARSE adjustment to results. Powder is a FINE adjustment to results.
When you calibrate anything, you adjust coarse first, then fine.