How do I seat long and keep the same pressure? QuickLoad or PressureTrace help!

[Happy2shoot]

Thought experiment here, but I would also like usable information as well, please.

Following a reloading manual, like Berger as an example.

If I seat a bullet longer than the book says without touching the lands pressure goes down. Correct?

Velocity would also goes down. Correct?

If I have a chronograph, I can increase my powder charge (small increments of course) till I reach my original velocity. Correct?

Bigger case volume with the same velocity would mean maximum average pressure (MAP) is still lower than the original pressure. Velocity is not a function of MAP, but rather a function of the area under the pressure curve. Correct?

Question:
After more powder is added to regain the original velocity how do I safely continue to increase the powder charge to equal the original MAP, and also gain a little additional velocity along the way?


Thank you for reading, and all you help.

Edited for additional information.

 

[rsmithsr50]

quickload is only a TOOL not a bible.
work up loads pretty simple

 

[Straightshooter1]

Thought experiment here, but I would also like usable information as well, please.

Following a reloading manual, like Berger as an example.

If I seat a bullet longer than the book says without touching the lands pressure goes down. Correct?

Velocity would also goes down. Correct?

If I have a chronograph, I can increase my powder charge (small increments of course) till I reach my original velocity. Correct?

All the above . . . Correct.

Bigger case volume with the same velocity would mean pressure is still lower than the original pressure. Correct?

No. . . not necessarily. For the most part, the pressure is pretty much tied to velocity, unless you're seated into the lands or compressing the load.

Question:
How do I safely increase the powder charge to equal the original pressure, and also gain additional velocity?

To get additional velocity, it'll take additional pressure to do it. . . . unless you do things like molly coat the bullets to reduce friction or reduce bullet mass like using a lighter bullet (things like that).

PS: as mentioned, QuickLoad is a tool and is really nothing more than a guild . . . nothing absolute there.

 

[BenPerfected]

.....just erased everything I typed. My advice is to find a knowledge local shooter who would be willing to help you get started. As in golf, there is a lot to learn in both sports and both can be expensive.
Ben

 

[mikecr]

How do I safely increase the powder charge to equal the original pressure, and also gain additional velocity?

Different powder, primer change, or possibly higher neck tension. Quickload, while calibrated to the system and in the hands of an experienced user, is excellent (and there is nothing else like it). But 'safely' doing things means following basic golden rules.

Reducing friction means nothing to pressure/velocity. Moly only reduces pressure because of it's latent heat of vaporization. As an example; if you reduce friction with Tungsten (way slipperier than moly) pressure/velocity does not change.
Also, raising neck tension does not mean simply squishing a neck down more. There can be more to it.

 

[INTJ]

Different powder, primer change, or possibly higher neck tension. Quickload, while calibrated to the system and in the hands of an experienced user, is excellent (and there is nothing else like it). But 'safely' doing things means following basic golden rules.

Reducing friction means nothing to pressure/velocity. Moly only reduces pressure because of it's latent heat of vaporization. As an example; if you reduce friction with Tungsten (way slipperier than moly) pressure/velocity does not change.
Also, raising neck tension does not mean simply squishing a neck down more. There can be more to it.

I remember Harold Vaughn taking about that in Rifle Accuracy Facts. While some
of what he did has become OBE, his moly test was solid. IIRC, he achieved the same pressure and velocity by loading the moly compound into the case as he did with coated bullets. That also seemed to correspond to the time when moly coating began to fall out of favor, though the widespread availability of inexpensive chronographs may have been the real reason for moly's demise.

We went from thinking moly increased velocity and allowed more rounds fired before cleaning, to thinking it just allowed longer cleaning intervals, to wondering what use it was when a good barrel could maintain top accuracy for as many rounds regardless of moly.

 

[Happy2shoot]

I added more information to the original post. Should be clear now. Hopefully someone comes along and re-reads this.

None of what I am saying above is new or obscure. I am only trying to find out how to do it without buying PressureTrace II.

I understand that reading primers, and measuring case head expansion is all voodoo. Proven to show false positives, and false negatives.

I am hoping someone has a method I haven't thought of, or just data collected from pressure equipment, or if nothing else someone could run this thought experiment in Quickload and see what pops out (example -6.5 Grendel, Max charge of VARGET, 130gr Berger, max coal- then move bullet out 0.02, how much powder to add to get original velocity, then how much to add to get original MAP and what is that final velocity? Thanks!

 

[jepp2]

If I seat a bullet longer than the book says without touching the lands pressure goes down. Correct?

To address your specific question. Several years ago I read the results of a study that varied bullet seating depth and the corresponding pressure.

- Seated deeper in the case tends to increase pressure but more run before encountering the lands reduced pressure. There was a point where the pressure was lowest (if I recall correctly is was around 0.050" off the lands). Closer less run, higher pressure even though there was more case volume available. Further greater run, higher pressure due to reduced case volume.

I don't know your reloading experience, doesn't matter. I use QuickLoad extensively, load for several wildcats there is no data on, and feel like I am able to do so safely. But I am conservative, utilize my prior experience with that powder lot and adjust the powder burn rate in QL for my calculations. And I shoot everything over a choro. So when velocities are increasing faster than my calcs, I stop and pull down the rest.

Some pressure signs don't show up until you are significantly above the max pressure for the cartridge. When you have expanded the primer pocket enough to have a blown primer, you are way high on pressure. Still bolt lift, same. Primers might or might not be a good pressure indicator. Relying solely on them can be misleading. I shoot a 26-06 a good bit. SAAMI max pressure for it is 65K. So I see a lot of cases fired at or near that pressure. And they don't look that different than my 223 loads that have a 10K lower pressure.

 

[JEFFPPC]

Thought experiment here, but I would also like usable information as well, please.

Following a reloading manual, like Berger as an example.

If I seat a bullet longer than the book says without touching the lands pressure goes down. Correct?

Velocity would also goes down. Correct?

If I have a chronograph, I can increase my powder charge (small increments of course) till I reach my original velocity. Correct?

Bigger case volume with the same velocity would mean maximum average pressure (MAP) is still lower than the original pressure. Velocity is not a function of MAP, but rather a function of the area under the pressure curve. Correct?

Question:
After more powder is added to regain the original velocity how do I safely continue to increase the powder charge to equal the original MAP, and also gain a little additional velocity along the way?


Thank you for reading, and all you help.

Edited for additional information.

Pay attention to bugholes not theroy.

 

[Straightshooter1]

or if nothing else someone could run this thought experiment in Quickload and see what pops out (example -6.5 Grendel, Max charge of VARGET, 130gr Berger, max coal- then move bullet out 0.02, how much powder to add to get original velocity, then how much to add to get original MAP and what is that final velocity? Thanks!

OK, let's use your example with a 6.5 Grendel using a 130 Berger VLD seated giving a cartridge overall length of 2.260; case capacity 37.5 gr H2O and 27.8 gr Varget. . . QuickLoad shows a pressure of 51,643 psi (just under the SAAMI max of 52,000 psi) and an MV of 2504 fps. (remember, the calculation are NOT absolutes, and just a guideline). So, if we move the seating depth out by .030 the pressure drops to 50,193 fps with an MV of 2490 fps. using the same powder charge. Then with that new seating depth gives a COAL of 2.290, increasing the powder load to 28.1 gr of Varget, QuickLoad shows a pressure of 51,879 and an MV of 2515 fps. So, QL is showing pressure very close to the previous load, but with a little more MV. Backing off the powder load to 28.0 gr of Varget, it shows virtually the same MV as before (2507 fps instead of 2504 fps) but with less pressure of 51,311 psi.

Again, these are just calculations that are a guide and most often are not in line with real world data where you can depend of these small differences calculated as having much correlation. And because of that, I simply use the QL info to help to with starting points when I make a change in bullet or powder to shorten the shorten the time and expense for load development.

 

[dttheliman]

OK, let's use your example with a 6.5 Grendel using a 130 Berger VLD seated giving a cartridge overall length of 2.260; case capacity 37.5 gr H2O and 27.8 gr Varget. . . QuickLoad shows a pressure of 51,643 psi (just under the SAAMI max of 52,000 psi) and an MV of 2504 fps. (remember, the calculation are NOT absolutes, and just a guideline). So, if we move the seating depth out by .030 the pressure drops to 50,193 fps with an MV of 2490 fps. using the same powder charge. Then with that new seating depth gives a COAL of 2.290, increasing the powder load to 28.1 gr of Varget, QuickLoad shows a pressure of 51,879 and an MV of 2515 fps. So, QL is showing pressure very close to the previous load, but with a little more MV. Backing off the powder load to 28.0 gr of Varget, it shows virtually the same MV as before (2507 fps instead of 2504 fps) but with less pressure of 51,311 psi.

Again, these are just calculations that are a guide and most often are not in line with real world data where you can depend of these small differences calculated as having much correlation. And because of that, I simply use the QL info to help to with starting points when I make a change in bullet or powder to shorten the shorten the time and expense for load development.

What Quickload cannot do is tell you what the spike is when you are jammed into the lans , you could be in diminishing returns territory very quickly - change one thing at a time and remember your chrono and your target results are your friend

 

[JASmith]

If you aren’t already using a chronograph, then start using one!

Then get an average of at least five shots for the two seating depths of interest.

Compare the two velocities. Is there enough difference that you can be statistically confident of the direction and size of the change.

Next, ask the question: “Is the change enough to make a difference that is greater than your typical group accuracy at the ranges of interest.

Changes are you’ll decide the reason for adjusting powder charge for the longer length is to get the best accuracy for that new length. That could result in either an increase or decrease in powder charge.

 

[Happy2shoot]

@Straightshooter1

Thank you so much for taking the time to run the numbers in your program. It was very nice of you.

And I see there is nothing to be gained after all. But it is nice to see that if one loads long without jamming you can add a little to keep your velocity.

I am really happy to get this resolved. I have been pondering this for a few years now.

Thank you to everyone who has taken the time to read and respond. Great place here. I joined just to ask this question.

 

[mikecr]

What Quickload cannot do is tell you what the spike is when you are jammed into the lans

That's where you use QuickLoad's suggested Starting Pressure adjustments. It works better than you may think, including increasing powder burn rate with this.

Try this: Whenever you think a matter of internal ballistics can't be calibrated or compensated for in Quickoad -> YOU'RE PROBABLY WRONG

 

[Ned Ludd]

As illustrated by Straightshooter1 above, extending the freebore can buy you a reduction in pressure at a given velocity, and possibly a small increase in velocity. Alternatively, it may simply allow you to achieve the same velocity at slightly lower pressure.

However, there are a couple things worth consideration. First, just because you can generate a little more velocity before exceeding MAX pressure doesn't mean the rifle will actually tune in at that higher velocity with a given powder/bullet/primer combination. Unless extending the freebore allows you to hit a higher accuracy node that was previously slightly out of reach, you may not gain any velocity at all.

Second, although extending the freebore may allow you to run slightly higher velocity, it may also be getting pretty far down in the weeds with regard to the magnitude of any increase, whether the rifle/load actually tunes in at the higher velocity or not. An increase in velocity of anywhere from a few fps to as much as 20-25 fps is not a monumental change and is not likely to represent a difference that most people could even shoot. Think of it as somewhat analogous to changing the seating depth of a bullet. For jumped bullets, certainly the pressure increases as you seat the bullet farther and farther off the lands, thereby reducing the effective internal case volume. However, you have to change the seating depth by quite a bit before the magnitude of the velocity change becomes significant. I can generally seat bullets anywhere from close to touching the lands, to as much as .030" off the lands without dramatically affecting velocity. So again, the effect is there, but it isn't a huge, easily noticeable difference until you start moving the bullet by .030", .040", .050", or more.

If you're not loading to mag length, the numbers in reloading manuals aren't a great deal of use, IMO. As a general rule, I will seat a bullet at .015" off the lands to start. I prepare a QuickLoad file using every possible accurate input that I actually have at the time (i.e. COAL, bullet OAL, barrel length, case trim length, etc.). Sometimes, I don't always have an accurate case water volume measurement initially. I then increase charge weight until I find predicted MAX pressure. Once a theoretical MAX pressure has been located, I drop the charge weight by anywhere from 2% to 5%, load a few rounds, and determine actual average velocity for that charge weight. Then I go back and adjust the temperature input to the actual ambient temperature, and adjust the factory preset powder burn rate (Ba) until the predicted velocity exactly matches my measured average velocity. This process is what I refer to as "calibrating" QuickLoad to a given rifle/load combination. From that point on, QL predictions are usually pretty good, although the farther away your "calibration" velocity is from the final velocity you achieve with your load, the more the Ba may need to be tweaked during the load development process.

My point about this is that QuickLoad is a tool, nothing more. But it can help to expedite load development, especially when you aren't loading to the same COAL in the reloading manuals. You still have to load the test rounds and shoot them so that the targets, velocity data, and any other indicators you might use can tell you what is optimal, but QL can help you get there little faster. Further, you can do the load development in an unbiased manner, letting the rifle tell you where it wants to shoot. Trying to fudge up pressure/velocity estimates for loads with a different COAL using the values from a reloading manual can be problematic.

 

[dcali]

The variation in pressure will be greater than the change due to searing depth. Strain gage systems are not very accurate for absolute measurements for a few reasons, the main one being the lack of a simple way to calibrate them. It will get you in the ballpark, but they’re not really meant for this sort of thing.

Long story short, quickload says it’s a few hundred psi, and you can play with that to bump powder enough to compensate. It depends on a lot of variables. But it’s just math, and you’re pushing the software beyond its limits when you ask that much of it in my view.