seating depth vs powder charge

[Chris kloster]

I switched powders middle of barrel life on my current F/open gun. I tuned the charge to the existing seating depth and ended up within 10fps of original velocity.

I always tune seating depth first to reduce the noise in reading powder charge tests.

So I was reading this comment, and I actually hadn’t considered seating depth first EVER. But you know what. Man it makes good sense. I think I’ll give it a try, thank you!

 

[Clancy]

So I was reading this comment, and I actually hadn’t considered seating depth first EVER. But you know what. Man it makes good sense. I think I’ll give it a try, thank you!

If you do your depth first, you’ll find wider and more forgiving accuracy nodes with your powder. I promise ya.

 

[Bill Norris]

If you do your depth first, you’ll find wider and more forgiving accuracy nodes with your powder. I promise ya.

Wondering how you can do seating depth first without knowing where to start with the powder?

 

[Raydee]

Wondering how you can do seating depth first without knowing where to start with the powder?

Exactly my thoughts too. Obviously if you have a known powder that should be ok but otherwise, I would want to work up the charge first.

 

[Kracken McGraw]

Wondering how you can do seating depth first without knowing where to start with the powder?

For book load cartridges, seems like backing off a grain or grain and a half from max load woks pretty good. Those guys pushing benchrest loads hard, I don’t know.

 

[Bill Norris]

For book load cartridges, seems like backing off a grain or grain and a half from max load woks pretty good. Those guys pushing benchrest loads hard, I don’t know.

But, lots of times now-a-days we are dealing with a cartridge not listed in manuals so I can see where that may be an issue for a new shooter just starting out with one of those cartridges.

 

[Bc'z]

Wondering how you can do seating depth first without knowing where to start with the powder?

Back off of max a couple grains to do seating.
If it's a cartridge not listed take a general concensus as to max/accuracy node others are shooting, again back off and shoot seating test.
GRT & Quickload programs also help to find a sane and safe starting point.

 

[Fast14riot]

But, lots of times now-a-days we are dealing with a cartridge not listed in manuals so I can see where that may be an issue for a new shooter just starting out with one of those cartridges.

For odd combinations, wildcats, completely new cartridges or old obsolete ones, I always do a coarse pressure ladder first. 1 shot each at about 1% increments, so that way I have a functional max and velocity.

To work up loads, I pick a middle of the road charge/powder that gives me roughly 90% fill ratio, and then start my seating depth test. I seat everything very long and take my arbor press to the range. If the second shot isn't close to the first I just move on to the next. You can't shoot a group smaller with more shots.

Here's the cool thing about improved cartridges, you can do seating depth testing while fire forming. I do it all the time in my 260AI. It might not always translate perfectly to the formed case but you will be very close and can often find it with less than 12 rounds.

 

[R&B]

I heard that seating depth is more important to accuracy than the powder charge. Is there any truth to this ?

Like the universe we all live in things are much more complicated than they seem. It would be nice if there where simple 1 dimensional answers to any and all questions.

The key to accuracy is achieving precision first. That is why so many purchase components in lots. Seating depth and powder charge are the 2 main variables we have direct control over when it comes to changing pressure. All we are really doing for the most part is finding the magic pressure level in barrel behind the bullet. The fun for me is trying to figure out what the barrel and bullet like. Sometimes it is not the logical answer we seek. I have a .204 that like inexpensive bullets and lots of Benchmark powder. My Anschutz rifle likes .22lr Aguila match target ammo as much or more than Eley or Lapua match ammo . Having the patients to figure out the right combination is what has drawn me to the sport. I enjoy exploring and working on the system as a whole. The system includes me as the shooter. The shooter is the one big variable that doesn't seem to be discussed too often in this forum.

-R&B

 

[450BM]

Like the universe we all live in things are much more complicated than they seem. It would be nice if there where simple 1 dimensional answers to any and all questions.

The key to accuracy is achieving precision first. That is why so many purchase components in lots. Seating depth and powder charge are the 2 main variables we have direct control over when it comes to changing pressure. All we are really doing for the most part is finding the magic pressure level in barrel behind the bullet. The fun for me is trying to figure out what the barrel and bullet like. Sometimes it is not the logical answer we seek. I have a .204 that like inexpensive bullets and lots of Benchmark powder. My Anschutz rifle likes .22lr Aguila match target ammo as much or more than Eley or Lapua match ammo . Having the patients to figure out the right combination is what has drawn me to the sport. I enjoy exploring and working on the system as a whole. The system includes me as the shooter. The shooter is the one big variable that doesn't seem to be discussed too often in this forum.

-R&B

And if you really want to have fun, try making a cast bullet work in a rifle as well as the jacketed ones do! Lol, I fell down this rabbit hole 5 years ago! I’m also convinced all my guns shoot a lot better than I can and I’ll never win a bench rest competition because I’m way too inconsistent. I have some rifles that might do well but not with me pulling the trigger!

With that said, I have a question for you guys that know a lot more than me…

Taking bullet jump out of the way, if you used different powders and loaded to the same velocity for that bullet, does the powder fill matter? And lets just say the SD for the different powders is the same.

 

[Pete Wass]

I have been using .006" in from just touching for years and find the best load for it. From stuff I've seen on YouTube, .006" in with .002" neck tension gave the best results in several tests. That squares with my results. I shoot a 30 BR and preload with exactly weighed charges. Most of the time it works the very best.

 

[Bill Norris]

I would rather ensure I’m in a node vs an anti/scatter node prior to serious testing of a seating depth.

Yea, kind of seems backwards to me but different strokes for different folks I guess.

 

[Bill Norris]

I’m a start with a bullet on the lands and run powder test first kinda guy. From there I’ll test seating depths.

I like the Boyer method checking powder charge & seat depth together after I find a range of powder under the higher pressure load.

 

[Steve Donlon]

From everything I have read most of the BR guys Jam them anyway to keep every thing as simple as possible. It works for them. I like to tinker around with all the possibilities. I put the bullet where I think it should be, then go from there.

 

[Fast14riot]

I would rather ensure I’m in a node vs an anti/scatter node prior to serious testing of a seating depth.

I find that any top notch barrel of a heavier profile (like BR and F use) will shoot appropriate target bullets reasonably into smallish groups at short range without terribly scattering due to powder charge.

Thinner barrels like a 30" light Palma are going to show much higher variation in group size.

Hunting profiles are a whole different ball game when it comes to load tuning.

 

[Steve Donlon]

Wondering how you can do seating depth first without knowing where to start with the powder?

If you seat the bullet with all of its'bearing surface in the neck most of the time the right powder charge will be at the base of the bullet or compressed a little. At least with the bullets I use. The last one I did was a 144 gr. 6.5 berger. It has .105 jump but the powder is right where it should be with 41.5grs of RL 16 powder and shoots great. It will jump just fine. Same with a "06" and the Berger 155.5 FB bullet. Same thing and that bullet has very little bearing surface and will jump over .1000". Very accurate with 53 grs. of IMR 4064.

 

[R&B]

And if you really want to have fun, try making a cast bullet work in a rifle as well as the jacketed ones do! Lol, I fell down this rabbit hole 5 years ago! I’m also convinced all my guns shoot a lot better than I can and I’ll never win a bench rest competition because I’m way too inconsistent. I have some rifles that might do well but not with me pulling the trigger!

With that said, I have a question for you guys that know a lot more than me…

Taking bullet jump out of the way, if you used different powders and loaded to the same velocity for that bullet, does the powder fill matter? And lets just say the SD for the different powders is the same.

Yes, powder fill matters. Some reloading manuals will even give you the percentage of case fill (Nosler). The manuals will even tell you when the load is compressed. The amount of space the powder fills versus how much is empty affects the way the powder burns (internal ballistics) or makes pressure. The same goes for temperature and other environmental factors. Powders, like most everything in the system, are dynamic. That is why short range bench rest shooters load at the bench during competitions. They are tuning in real time based on environmental conditions and or the guns changing behavior. Most of the time they are just playing with powder charge.

R&B

 

[Fast14riot]

I can’t tune a long range rifle at short range worth a damn, it just doesn’t work for me, everything looks the same. lol

And that's fine. Short range tuning is not where final tune is found, unless its a short range gun and load. But, I do think that anyone can tune a load at short range to take to distance and perform reasonably well with final tune completed at distance. There are layers to rifle tuning.

 

[Clancy]

@Bill Norris sorry I didn’t see ya but I think it’s been covered a few times. Start with something known and reasonable for depth and then work up once the depth is found. I have never had someone come back and tell me they didn’t like this order better.

The only thing I’ve worked on in a long time that was “new” was the 6GT and I just started in the middle of book data for the depth test and it worked out great.

I guess if I had to have something off the books, I’d start at the longest point I’d load and shoot a one shot pressure test then do the depth first like normal.

 

[Pete Wass]

From everything I have read most of the BR guys Jam them anyway to keep every thing as simple as possible. It works for them. I like to tinker around with all the possibilities. I put the bullet where I think it should be, then go from there.

I want to be able to open my bolt without pulling a bullet if it is necessary, such as a bad primer or some safety reason. I found @ .006" in, I can always do that. .006' won't stick a bullet into the lands with any rifle I have ever had to use in competition. I don't find it difficult to find nodes with my method. A tuner in the hands of an experienced user will keep one on the node, from what I have seen. I have never liked the idea of jumping bullets for some reason. I know it works the very best but I just have never been there.

Years ago, like 20, lets say, I used to test till all the cows came home. I found that EVERYTHING matters. .001" of seating depth matters as does .01gn of powder matters. Comes the question, particularly in todays world of cost of barrels, Smithing and components. How much is it worth to absolutely wring every possible iota out of a barrel? One can easily burn the "goody" out of a great barrel testing constantly. I find that a given load stays the same one barrel to the next with very minor differences. A simple ladder of powder charges in .02gn increments will nearly always yield a group in the small teens at my constant .006" in. The rest is in the windflags.