No problem. I hope some find this useful and helpful. It sure has made things easier for me when doing load development. Shooting, reloading, and hunting are my main hobbies and what I live to do. I like to pass on what I have learned and experienced to others because I've had problems developing loads and still run into issues sometimes. But having good data and good methods makes life a lot easier haha
Seating Depth Informative Thread
- Thread starter Jud96
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ajkellerusmc
Well-Known Member
Ahh just joking! Not everyone does things in the same order which makes me confused. I have my powder charge selected and now Im on to adjusting seating depth and then I read from someone that He does powder adjustments after seating depth tests.
Yeah haha there's more than one way to skin a cat. I personally start .010-.020 off the lands and find my powder/velocity node first. Once I find the velocity node, I go back and find my seat length node. Seating depth can change your velocity node. Sometimes the node stays and you gain or lose a little velocity or it doesn't change much at all. Other times you might have to go back and adjust your powder charge a little to get back in the node. You can work opposite too. I've seen plenty of guys start at the minimum load and find their seat depth node first then work up in powder. This works too. Whatever way you start will work in the end. You might just have to do some slight tweaking when you're finalizing everything. It's very important to keep good notes and track everything. It's easy then to go back and look at your data and not get lost or not know where to start over or what have you.
I should clarify as I kind of skipped over the first part of my load dev.. My step 1 is finding max pressure, so I work up powder charges, one shot each, in .3 or .5 grain (depending on case capacity) increments and shoot each over a chrono until I see pressure signs and then call that max.
Then I graph the chrono data to see if there's a flat spot in the velocity and do my seat depth test in the middle of that.
After the seat depth test, then I shoot a real ladder test at 300 yds. The nodes sometimes line up with the chrono data, sometimes not. the crono data is limited sample size so I am only using it as a baseline.
It's kind of a back and forth as each variable effects the other like Jud said, but the seat depth is definitely the more "coarse" of the two.
Then I graph the chrono data to see if there's a flat spot in the velocity and do my seat depth test in the middle of that.
After the seat depth test, then I shoot a real ladder test at 300 yds. The nodes sometimes line up with the chrono data, sometimes not. the crono data is limited sample size so I am only using it as a baseline.
It's kind of a back and forth as each variable effects the other like Jud said, but the seat depth is definitely the more "coarse" of the two.
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Creedmoor shooter
Well-Known Member
I guess I've never seen a huge difference in seating depth with my particular rifles and bullet choices. I generally see no to little difference with a .005 depth change. Generally I rough i pick a slight below max charge and start with seating depth with .020 increments. When I find something that's close I'll go .010 on either side. Pick the best one of those then fine tune with powder and working up to pressure. Still good stuff and very informative! It's so weird how so many people have so many different experiences
IHFarmer07
Well-Known Member
Elf, what powder load do you start off with, the middle of a charge weight or? I'd like to try this but never really knew where to start at with a powder charge. Do you do a pressure ladder or something similar first then where do you go? What do you mean when you say you begin a new sequence with another powder/primer? Can you elaborate?
I use the Sinclair overall length tool along with wooden dowel rod down the muzzle to make sure I don't get the bullet too far stuck into the lands.
ajkellerusmc
Well-Known Member
I should have went to college to be a scientist ! Great info though.
Haha I'm far from a scientist. Just a machinist and a guy that's really into reloading and precision. I try to work well with my hands and mind, sometimes it works out haha. I'm data driven with my handloads and rifles and I like to find proven methods and stick to them. Some guys dread load development, but I do it for fun to test new things and prove theories and learn new stuff every time.
Idaho Hunter1
Well-Known Member
So I am fairly new to reloading for precision rifles and the loading I have done in the past is simply to replicate the factory ammo for cost benefit of getting to shoot more.
Now I'm in a position in life to be able to tinker with loads with better quality components and I'm starting to do just that. I have a question regarding reloading data related to seating depth. If I see a COAL in a reloading manual of 3.500" and a powder charge, I notice that the COAL doesn't change usually with bullet weight but the charge does. I understand the charge variable changing but the COAL would change also I would think. Is the COAL a minimum? Maximum? Or some nebulous middle point?
Now I'm in a position in life to be able to tinker with loads with better quality components and I'm starting to do just that. I have a question regarding reloading data related to seating depth. If I see a COAL in a reloading manual of 3.500" and a powder charge, I notice that the COAL doesn't change usually with bullet weight but the charge does. I understand the charge variable changing but the COAL would change also I would think. Is the COAL a minimum? Maximum? Or some nebulous middle point?
The COAL in a loading manual is typically the SAAMI recommended length for that particular cartridge. That means if you load ammo to that overall length it will fit, feed, function, and be safe in all guns chambered in that caliber. You really don't want to go below their set length because you could run into premature pressure issues and other problems. Typically, you have room to seat the bullet out before you hit the rifling. You will normally find your best accuracy somewhere closer to the rifling than with what the manual recommends, in most cases. You can still find good accuracy at the book listed COAL with some bullets, but others, particularly long, heavy, VLD bullets like to be seating closer to the lands. If you want to start experimenting with seating depth, I recommend finding your lands with a Hornady OAL tool or by seating a bullet into a sized case extra long and slowly seat it deeper with your die until you stop feeling resistance when closing the bolt. If you use the later method, you have to remove your firing pin assembly and plunger ejector, if your bolt has that style ejector. This will allow the bolt to drop closed effortlessly when the chamber is empty. You want it to get to the point when chambering the dummy round where you can just start to feel it close easily. That will be where your rifling is, with that particular bullet. Every different bullet will touch the rifling at a different spot. So you have to do this every time you change bullet types, if you want to find your lands. This is the best method I have found and it sure beats any guessing or confusion.
Savage 12BVSS
Well-Known Member
This is good stuff here. A great load comes slow with a lot of shooting tests. When I get down to the fine part of seating depth I'm moving .001 at a time...with powder charge its tenth of a grain at a time till I get to tightest group. You can watch the groups tighten as you go.
Okanogan
Well-Known Member
For determining when the bullet is just touching the lands in my bolt guns, I have found lifting the bolt without feeling any resistance to be more repeatable for me than trying to do the same thing based on bolt closure. Wheeler Accuracy has a good video showing what I eventually adopted as my preferred method for determining max length without being in the lands. I use the Hornady tool for my ARs but practicing with it on my bolt guns tended to give me 0.010-0.020 inches into the lands compared to the Wheeler Accuracy method. For most of my AR platforms it doesn't matter because max COAL is controlled by mag length but for rifles like the Valkyrie, it does matter for some bullets.
My experience has been seating depth is very important in my load development but not to the point I would have characterized it a single over riding factor with group size. I have two GAP 300 WMs and have found I can vary group size with them after optimizing seating depth just as much with velocity as I could with seating depth. With the lighter barreled (#3 Bartlein) the groups open up as I increase velocity above 2800 fps with Berger 215s. The heavier barreled (#6 Bartlein) is just becoming happy above 2850 fps with Berger 215s. I attribute this behavior to different barrel harmonics. Without a good chronograph it would be very difficult to figure out what was going on.
The basics of load development require picking one variable and optimizing it before moving onto the next variable and then fine tuning later. I agree with the basic premise of the thread and for my bolt guns, I usually start with varying seating depth and then move to powder/ velocity. For an AR platform rifle though, I often start with powder/ velocity because I'm generally more limited in my ability to adjust COAL to be near the lands if I want to stay with-in magazine length limits. As indicated in various threads, others on the forum do things in a different sequence and I don't disagree with how they chose to do their load development.
I like the way that Adam McDonald of Autotrickler fame described load development in one of his early posts. Paraphrasing, he said rightly or wrongly he would assume group size was dominated by seating depth and SD/ES was dominated by powder charge/ selection. He just changed one variable at a time to optimize each and then cycled back trhough to fine tune.
My experience has been seating depth is very important in my load development but not to the point I would have characterized it a single over riding factor with group size. I have two GAP 300 WMs and have found I can vary group size with them after optimizing seating depth just as much with velocity as I could with seating depth. With the lighter barreled (#3 Bartlein) the groups open up as I increase velocity above 2800 fps with Berger 215s. The heavier barreled (#6 Bartlein) is just becoming happy above 2850 fps with Berger 215s. I attribute this behavior to different barrel harmonics. Without a good chronograph it would be very difficult to figure out what was going on.
The basics of load development require picking one variable and optimizing it before moving onto the next variable and then fine tuning later. I agree with the basic premise of the thread and for my bolt guns, I usually start with varying seating depth and then move to powder/ velocity. For an AR platform rifle though, I often start with powder/ velocity because I'm generally more limited in my ability to adjust COAL to be near the lands if I want to stay with-in magazine length limits. As indicated in various threads, others on the forum do things in a different sequence and I don't disagree with how they chose to do their load development.
I like the way that Adam McDonald of Autotrickler fame described load development in one of his early posts. Paraphrasing, he said rightly or wrongly he would assume group size was dominated by seating depth and SD/ES was dominated by powder charge/ selection. He just changed one variable at a time to optimize each and then cycled back trhough to fine tune.
I'm just starting with precision rifle. Don't have the budget to get to carried away so on the advice of a friend bought a 308 Remington 700 rifle. If I seat the bullet .010 from lands it will not fit the magazine. Heck it only has about 20% of a168 gr. bullet in the case. (Remington getting sloppy?) better left to a different thread. So I am using the OCW method then I play with seating depth. Have found a decent recipe but have not been able to test it past 200 yards yet. My 243 likes the Sierra hollow points at about .020 off. Any other advice?
Okanogan
Well-Known Member
For rifles where I can't work close to the lands because of some constraints, I usually try a few different bullets that are supposed to be more jump tolerant. Berger Hybrids and full bore have tended to work well for me. The Berger VLDs are generally more sensitive. The Elite Hunters are supposed to be more tolerant but haven't worked too well for me yet.
Hornady bullets are more economical and many report good results with ELD-M or ELD-X. I haven't generally been able to get as good of groups with the Hornady bullets with most of my rifles, but my 308 does well with SSTs which are being jumped in an AR platform.
Having a good chronograph, even if you have to borrow one, also helps in providing critical information during load development and in controlling variables.
Hornady bullets are more economical and many report good results with ELD-M or ELD-X. I haven't generally been able to get as good of groups with the Hornady bullets with most of my rifles, but my 308 does well with SSTs which are being jumped in an AR platform.
Having a good chronograph, even if you have to borrow one, also helps in providing critical information during load development and in controlling variables.
