Powder charge and seating depth

[6pakzak]

Yes I was reading on another forum where a guy said he called bullet maker can't remember which one but they told him to find the seating node first I believe they said this because of the pressure changes, I have what I believe is a good combo for my 223 savage cause I have it grouping about .3 but I haven't chronoed it yet. I guess that's what I'm trying to find out, is it powder first and then seating, and will powder stay the same no matter where I seat it in the end.

 

[6pakzak]

Cortina says not to worry about groups when doing powder, he says only thing your looking for is low spreads, I'm only putting this out there cause some in this thread are talking about groupings with powder

 

[6pakzak]

Yes, I find a node, for example in my 6.5 SAUM using 153.5 Bergers, I found a node at 58-58.9. I use .3 increments. I had a nice little group going up and up and then it opened up. On that node I used 58.5 gr. It was right in the middle of the node and groupings. I then tested seating depth and found that the .033" off grouped the best and .083" off. Always go with the closer to the lands seating depth. because as the throat wears down you know you can seat them longer and still get good accuracy.

going with the middle node allows for certain factors, warm barrel, warm weather, cold weather, etc... Dan Newberry goes into good detail about it

If your .083 was a better group couldn't you still seat them longer to be in the node?

 

[waveslayer]

If your .083 was a better group couldn't you still seat them longer to be in the node?

No because longer didn't group well. As for powder charge, as you change your seating depth you vary the pressure, hence why to pick a middle ground node. It will take into account those variances .

As for Cortina, he knows what he's doing but a lot of it can be proven wrong too... find a node or velocity you want, do seating depth and waste money on shooting the gun.

 

[6pakzak]

No because longer didn't group well. As for powder charge, as you change your seating depth you vary the pressure, hence why to pick a middle ground node. It will take into account those variances .

As for Cortina, he knows what he's doing but a lot of it can be proven wrong too... find a node or velocity you want, do seating depth and waste money on shooting the gun.

I was just saying if it did shoot better as a hypothetical, so your saying that the powder change may not stay the same if you had to seat further?

 

[WildRose]

I was just saying if it did shoot better as a hypothetical, so your saying that the powder change may not stay the same if you had to seat further?

Both change peak pressure and harmonics.

 

[6pakzak]

Your concerns are right, and what you're seeing is typical in that approach. The reason grouping falls apart with your seating testing is because your doing the testing from your powder node. That testing is then collapsing the powder node -causing 2 big changes at once. It's tail chasing. My approach is to mostly follow Berger's recommended full seating testing. A key point in that is to lower the charge considerably for the testing. I don't know, they may suggest that for safety, but it's actually critical to best results. It should reasonably take you away from any powder node, and with that you can focus more on results of seating, even while grouping is large at that point. THEN, with best coarse seating, you can move into powder testing for either tightest grouping or low Es, or best cold bore accuracy, etc. Your choice. THEN after powder with best coarse seating, move to fine tweaking of seating (inside it's window) for tightest group shaping. This doesn't take more shots, as full seating testing can be done while fire forming brass, and it doesn't take a lot of shots for coarse testing with Berger's recommended increments. Another worthy point in this approach is that you'll be going into powder with tested seating, instead of something pulled out of somebody's butt. After all, how can a bullet maker or anybody else predict where your COAL should be? They know nothing of YOUR chamber throat. If you go by their guess then how do you know your seating -during powder testing- was not the worst possible? This, potentially causing really crappy ladders, and masking best powder load. The same applies to primer swapping. It's likely a waste of effort to do that from a good powder node..

So if

Your concerns are right, and what you're seeing is typical in that approach.
The reason grouping falls apart with your seating testing is because your doing the testing from your powder node.
That testing is then collapsing the powder node -causing 2 big changes at once.
It's tail chasing.

My approach is to mostly follow Berger's recommended full seating testing. A key point in that is to lower the charge considerably for the testing. I don't know, they may suggest that for safety, but it's actually critical to best results. It should reasonably take you away from any powder node, and with that you can focus more on results of seating, even while grouping is large at that point.
THEN, with best coarse seating, you can move into powder testing for either tightest grouping or low Es, or best cold bore accuracy, etc. Your choice. THEN after powder with best coarse seating, move to fine tweaking of seating (inside it's window) for tightest group shaping.
This doesn't take more shots, as full seating testing can be done while fire forming brass, and it doesn't take a lot of shots for coarse testing with Berger's recommended increments.

Another worthy point in this approach is that you'll be going into powder with tested seating, instead of something pulled out of somebody's butt. After all, how can a bullet maker or anybody else predict where your COAL should be? They know nothing of YOUR chamber throat.
If you go by their guess then how do you know your seating -during powder testing- was not the worst possible? This, potentially causing really crappy ladders, and masking best powder load.

The same applies to primer swapping. It's likely a waste of effort to do that from a good powder node..

So if I'm understanding what your saying you seat at the lowest coal and then work your powder up from beginning load?

 

[Lefty7mmstw]

Not that I would ever encourage anyone to do anything unsafe but keep in mind that all our load manuals pass through the hands of the liability lawyers before they go to print so their maximums are usually 10-15% reduced over what is actually safe.

Caveat: If you are loading into the lands very close or even jamming pressure spikes will be much greater with a given load than if you give the bullet some jump.

Not from what I've seen... many rifles I have are actually running published speed a bit below max. charge. Most of the wiggle room is set aside for component variations, not lawyers. I've seen factory ammo and book loads hit north of 70 Kpsi on a strain gauge. You Can probably get by with 75 Kpsi if you don't want brass life and you don't really like your rifling or your face though.
If you want more performance, buy a bigger hammer. Running it harder will just burn you eventually. Kinda reminds me of when everyone was running rl33 hard as heck in the 300rum with 220-230 grain pills, until they started blowing brass in hot weather. They were running 100-102 grains; I said 95 was about max. from what I'd seen. I'm still getting 3,000 fps from rl33 safely; those who didn't heed velocity as a pressure warning (some were at 3150-3200 fps) still grouse that rl33 is a problem powder when it is in fact dangerous reloading habits on their part that were the primary issue.

 

[WildRose]

Not from what I've seen... many rifles I have are actually running published speed a bit below max. charge. Most of the wiggle room is set aside for component variations, not lawyers. I've seen factory ammo and book loads hit north of 70 Kpsi on a strain gauge. You Can probably get by with 75 Kpsi if you don't want brass life and you don't really like your rifling or your face though.
If you want more performance, buy a bigger hammer. Running it harder will just burn you eventually. Kinda reminds me of when everyone was running rl33 hard as heck in the 300rum with 220-230 grain pills, until they started blowing brass in hot weather. They were running 100-102 grains; I said 95 was about max. from what I'd seen. I'm still getting 3,000 fps from rl33 safely; those who didn't heed velocity as a pressure warning (some were at 3150-3200 fps) still grouse that rl33 is a problem powder when it is in fact dangerous reloading habits on their part that were the primary issue.

I've had the guys publishing the manuals expressly tell me their published maximums are well below what they deemed safe specifically because of potential liability.

Note that in the video above he tells us the exact same thing.

As always the same applies, start low and work up till you find your happy place.

 

[Mikecr]

So if I'm understanding what your saying you seat at the lowest coal and then work your powder up from beginning load?

No,,
I suggested doing full coarse seating testing at a lower charge, well away from your powder node.
Don't mix up tuning with bullet seating. Separate them.

 

[waveslayer]

Both change peak pressure and harmonics.

I agree, but one thing I now question is about Harmonics...
Let's take FGMM loads, .308 or 300WM to keep it simple. They shoot so well out of all sorts of shapes and sizes. Meaning different barrel lengths, barrels, stocks, how the rifle is shot , and it all prints nice little groups.... there's no way harmonically that FGMM ammo or even Prime ammo is tuned to everyone's rifle unless Harmonics aren't as important than we think.
It makes you pause and wonder if Harmonics is not as big of a deal as we think... then you get the barrel tuners involved. Crazy to think about. According to some they say it's too hard to measure

 

[Kmccord]

Lots of ways to get where you want, my method is what Berger recommends, I talked to one of the techs and this is what he recommends. Use the minimum powder charge for your particular cartridge and bullet, the use the seating depth tests they have outlined, see attach URL. Once you find the group, I also use the Chrono to see my ES/SD for each group, once you find the group, then start testing charges. I did this and found one pretty quick for a factory Bergara 7 Rem Mag. Once you get it dialed in, you need to test it and make sure it will repeat the same, you can also fine tune if need be, then test it out to 600yards. Some people even use 600 as the bench mark to find a load and fine tune it at that distance as well.

VLD - Making it Shoot

VLD bullets are designed with a secant ogive. Berger VLD bullets are consistently and exceptionally capable of putting game down quickly

bergerbullets.com

 

[RUFFIAN R - NY]

go to an old loading book 63-64 and compare then and now .. got to love them lawyers !!!!!!

 

[Mikecr]

According to some they say it's too hard to measure

I tried it with a laser mic trained on the muzzle, and feeding DAS sampling. Didn't work.
It was sensitive enough but not fast enough. When I looked into resolving that, the price of the endeavor went out of control. $10K+ just for the needed sampling software..
The vibrations definitely matter though. Press against your action tang with a thumb in the middle of your next group.
Jam a piece of cardboard between your barrel and stock. It doesn't affect your load, but look at what it does to POI.