What distance to the lands are you using? (12BVSS)

[darkker]

No but it will narrow down the possibilities. Instead of 20 loads I would be testing maybe 5 per bullet. I already have a chronograph so I would be checking velocity as I shot.

Maybe it would. If I sent you into an engineering test you knew nothing about, but gave you a calculator; would it save you a significant amount of time?

The Pressure Trace lists OBT markers as well, and just like in QL they are estimates. Even if you look on Varmint Al's excellent page for barrel travel time, you'll see he assumed a constant acceleration rate. Since we know bullet acceleration isn't a constant speed, how accurate are the calculations?:rolleyes:
From looking at a bunch of my traces, it's only reasonably clear where actual barrel exit is when I was chatting some secondary ignitions. Even then, some loads which are known as both accurate and inaccurate, may or maybe jive with the OBT markers.

Again, QL is fin for what it is; just don't expect it will solve many of life's burning questions for you.

Cheers

[Ted_Feasel]

Maybe it would. If I sent you into an engineering test you knew nothing about, but gave you a calculator; would it save you a significant amount of time?

The Pressure Trace lists OBT markers as well, and just like in QL they are estimates. Even if you look on Varmint Al's excellent page for barrel travel time, you'll see he assumed a constant acceleration rate. Since we know bullet acceleration isn't a constant speed, how accurate are the calculations?:rolleyes:
From looking at a bunch of my traces, it's only reasonably clear where actual barrel exit is when I was chatting some secondary ignitions. Even then, some loads which are known as both accurate and inaccurate, may or maybe jive with the OBT markers.

Again, QL is fin for what it is; just don't expect it will solve many of life's burning questions for you.

CheersThe biggest problem I've found on my 28" heavy shilen is all the loads I've tried shoot excellent . Im starting from.scratch trying to find a load that is best. Im going with varget this time and as ridiculous as it sounds, I'm going in 10th gr increments with 5 of each. My scales are good to .02 gr but im going to find it lol.. I found it once before and my son lost my index card that had my load data.. I believe it was W748 that was hitting same hole in 5 shot groups

Sent from my SM-N975U using Tapatalk

[CFJunkie]

Ted,
In answer to your post #40:
You probably could use a calculator but you would also need to validate each powder for your bullet and rifle based upon results so it makes the process a lot like shooting a ladder. You just can't predict accurately what the result might be because you can't just use velocity.
I found that different powders with the same bullet not only generate different velocities for the same load, but because of their different burn characteristics, they accelerate down the barrel differently simply because the pressure builds differently. That means the exit times can vary even if the muzzle velocity is the same.
So far, I find that QuickLOAD manages to predict the differences in exit time for different powders pretty well and gets me in to the right exit time about 90% of the time when I try different powders.
QuickLOAD also lets you adjust for temperature with temperature sensitive powders, and that feature made getting rid of some of the data masking that occurred before I started to consider the change in velocity & exit time due to temperature effects on those temperature sensitive powders.

[Ted_Feasel]

Ted,
In answer to your post #40:
You probably could use a calculator but you would also need to validate each powder for your bullet and rifle based upon results so it makes the process a lot like shooting a ladder. You just can't predict accurately what the result might be because you can't just use velocity.
I found that different powders with the same bullet not only generate different velocities for the same load, but because of their different burn characteristics, they accelerate down the barrel differently simply because the pressure builds differently. That means the exit times can vary even if the muzzle velocity is the same.
So far, I find that QuickLOAD manages to predict the differences in exit time for different powders pretty well and gets me in to the right exit time about 90% of the time when I try different powders.
QuickLOAD also lets you adjust for temperature with temperature sensitive powders, and that feature made getting rid of some of the data masking that occurred before I started to consider the change in velocity & exit time due to temperature effects on those temperature sensitive powders.I'm wondering though (not arguing at all) and it sounds like you would know the answer.. I get and thoroughly understand burn rates and curves (similar how a funny car can have a let's say 290mph top speed at the end of a quarter mile@4.5 seconds but the slower car.. let's say had a lower speed 280 mph but had a 4.3 seconds time) .. anyways.. shouldnt you be able to chrono the muzzle velocity in fps of a given powder and from that divide by footage of barrel and obtain exit time for that load? Then if you have constants such as harmonic wave speeds of a given type of steel figure the same thing with a small margins of inaccuracies that should still get you in the ball park

Sent from my SM-N975U using Tapatalk

[CFJunkie]

Think of it this way.
The acceleration rate of a bullet with a particular powder will depend upon how the pressure builds as the powder burns.
I don't think you can assume that the build up is linear for each powder.
A change in burn rate would change the pressure curve and, therefore, the time it takes for the bullet to move down the barrel.
Also, if the powder burns longer and continually adds, or at least maintains pressure, the bullet may accelerate longer and add velocity.

You really would have to know a lot about the powder composition, not just the muzzle velocity, in order to determine what the exit time actually was.
QuickLOAD makes a point of explaining that they test every powder on their list to determine its burning characteristics (I can't remember the term they actually use) but I think that fills in the unknown area of what is happening from ignition to exit from the barrel.

I just don't know how to estimate that from muzzle velocity and barrel length.
The muzzle velocity measurement occurs after the bullet has completed all of its acceleration and is flying free after exiting the barrel.
That measurement doesn't give any indication of what the bullet did in the first, second, etc. microsecond after ignition.
It only takes about 1,000 to 1,400 microseconds to go from dead zero to muzzle velocity.
I just can't determine how long it gets to exit the muzzle based upon muzzle velocity alone.

For example, for a 77 grain SMK in my 26 inch barrel 12 FV to achieve a 1.361 msec. exit time:
a) N140 yields a muzzle velocity of 2,587 fps with 20.7 grains of powder at the seating depth I would use to get the jump I want with that particular barrel.
b) IMR4166 Enduron yields a muzzle velocity of 2,538 fps with 21.0 grains at a seating depth 0.002 further out.
c) H4895 yields a muzzle velocity of 2,620 fps with 20.5 grains at a seating depth 0.012 further out than N140.

All have the exact same exit time, but the muzzle velocities are all different.
I think that means that the acceleration rates down the barrel are all different too or else the muzzle velocities would all be the same.
Therefore, without the information listed above (that I got from QuickLOAD), I don't think you can predict exit time from muzzle velocity alone.

[charlie b]

Correct, it is the acceleration that has to be calcuated, vs the changing chamber pressure and powder burn rate.

And, yes, you can do this by hand if you have all the mfg powder data. There are some very specific burn rate equations for calculating pressures, velocities, etc. It takes into account the change in burn rate with changes in pressure as the bullet moves down the bore. A friend started me on the path to studying this after he wrote a program in Fortran to calculate a muzzle velocity. Then we started looking at sources for information which led us to the Army's ballistics labs and tech bulletins. The biggest problem back then was finding correct burn rates for powders, especially the triple base stuff.

If you go to the DTIC web site and look up Interior Ballistics of Guns you can find all the theory you want.

There is even an early computer program that was done.
https://apps.dtic.mil/docs/citations/AD0299980

Back in the 80's I went to Watervliet and Aberdeen (I was an instructor at West Point at the time) to see about small arms programs for interior ballistics. The Army had several for artillery but not for small arms. Their consensus was that it was easier to just test the loads, especially given the variation in powder lots.

Last thought, many powders are temperature sensitive, so one loading for exit time may not be correct if the temp changes by 50deg.

[Ted_Feasel]

Correct, it is the acceleration that has to be calcuated, vs the changing chamber pressure and powder burn rate.

And, yes, you can do this by hand if you have all the mfg powder data. There are some very specific burn rate equations for calculating pressures, velocities, etc. It takes into account the change in burn rate with changes in pressure as the bullet moves down the bore. A friend started me on the path to studying this after he wrote a program in Fortran to calculate a muzzle velocity. Then we started looking at sources for information which led us to the Army's ballistics labs and tech bulletins. The biggest problem back then was finding correct burn rates for powders, especially the triple base stuff.

If you go to the DTIC web site and look up Interior Ballistics of Guns you can find all the theory you want.

There is even an early computer program that was done.
https://apps.dtic.mil/docs/citations/AD0299980

Back in the 80's I went to Watervliet and Aberdeen (I was an instructor at West Point at the time) to see about small arms programs for interior ballistics. The Army had several for artillery but not for small arms. Their consensus was that it was easier to just test the loads, especially given the variation in powder lots.

Last thought, many powders are temperature sensitive, so one loading for exit time may not be correct if the temp changes by 50deg.Yeah, being I cant spend 150 on QL right now I think I'm going to give that method in the link I posted earlier and see if it works.

Sent from my SM-N975U using Tapatalk

[darkker]

Think of it this way.
The acceleration rate of a bullet with a particular powder will depend upon how the pressure builds as the powder burns.

Brilliant post, and right on the money.

Especially when a powder is a progressive burning animal, the curves just don't act anything like a "standard" powder.
And the continual swapping and blending in the canister world can really fool with you.

Cheers

[Robinhood]

Darkker I tend to agree but I don't think it is all doom and gloom. The variations are manageable enough.

[charlie b]

Yep, it is all manageable, just not easy to do the calculations. The $150 for Quickload is very cheap considering how much work it took to develop and keep up to date.

The alternative is the load ladder. Since I routinely use a chronograph it is the cheaper way to go.

[hardnosestreetcop]

I have one, I do all my seating on precision rounds by base to ogive measurements once I find the "magic" number.. it is a PITA to do that on a 100 or even 50 rounds but I've found if you pre measure all your pills and sort them by pill base to ogive (shocking the inconsistency in even the best pills) that you can do it with minimal adjustments on your seating dies [emoji4]

Sent from my SM-N975U using Tapatalk
Ted you don’t have to do that with every bullet in the box, just do it with one of them and that one you put in a small bag. That will be your benchmarke. For that class and brand of bullet.

[Ted_Feasel]

Ted you don’t have to do that with every bullet in the box, just do it with one of them and that one you put in a small bag. That will be your benchmarke. For that class and brand of bullet.You would think but you will find .001-003 variance in a box.. even bergers have a suprising amount of inconsistency from base to ogive.. berger and the new hornady ATips are the most consistent I've found with Sierra and hornady match being 3rd and 4th.. I was really suprised when I found. 003 difference in sierra and hornady eld match

Sent from my SM-N975U using Tapatalk

[darkker]

Darkker I tend to agree but I don't think it is all doom and gloom. The variations are manageable enough.

No it's certainly not doom and gloom, that's not the point I was trying to make; clarity is.

The OBT markers are estimates, not answers. Will it get you close? Sure, but frankly so does going out and simply shooting groups. And if $150 is a financial hardship, then I'm not sure much volume shooting is going to happen. That's not meant to be negative, just how it is for him at the moment.

Similarly for clarity about QL, many put a ton of faith in it's outputs as a fact; especially as it relates to pressures.
Generally speaking in it's current updated state, the calculations are reasonable given the inputs. The inputs are the problem.
Most folks think IMR, Winchester, etc make powder, and that canister grade is a tightly held standard; neither of those things is true without a huge asterisk.

Of the powders people in the US are likely to have much knowledge of, the actual producers are:
General Dynamics, Groupe SNPE, Thales, Nammo, Rhinemetal. All of which are either defence contractors, or state owned defense companies. None of which wake up concerned about the hand loading waste market.
I will say that Groupe SNPE seems to have given Hartmut anything he wants, as the calculations track consistently with real pressure testing. Others less so, and a fair number of the General Dynamics it can be dangerously wrong. So the natural question is why? I'm not positive, but there are a few reasonable explanations.

1) Canister blends. Powder gets blended for a number of reasons, just as it gets surplussed for a number of reasons. Ever make a batch of cookies, and every single one came out perfectly identical? Me either. Even from "sealed" containers moisture gain/loss occurs, and the burning curve changes. There is some excellent pressure data showing this, in one of the last two Norma manuals. Hodgdon does little of their own testing, and most of their own is with crushers.:wacko:
So it's perfectly reasonable to assume Hartmut used a fixed volume bomb calorimeter to test a bunch of powders he wasn't supplied info for. Same as gets used for "relative" burning rate charts. It's well known that volume changes burning rates and characteristics of powders. So a fixed volume bomb test really doesn't accurately describe a powder in anything other than that one volume setting. And if the next release of powder is much different, so are the results.

2) Silent supplier swaps. Anyone here reloading in the 90's when Hodgy swapped the bulk of their extruded supplies to Thales? That was a mess. Same as in the past couple years when GD was rebuilding the Quebec plant, and some of the IMR 8# bottles were sourced from Rhinemetal.

The point being:
If someone wants a thing they can play with and get some general insight from, it's a great little resource.
If someone wants to try and understand what a powder is actually doing, it can't give you those answers.
Different tools for different jobs.

Cheers

[Lefty Trigger]

Try loading to the listed length and see what happens. I found in my 6.5x47 Lapua if loaded to the book length my group sizes cut in half! Loaded to the book length in that rifle is a .076 jump to lands, same results in my 6mm Creedmoor, book length is a .050 jump and group size reduced a bunch. Give it a shot and you might be amazed.

[Fuj']

On single shot rifles, I start all my load work .015 off the lands.

[yobuck]

On single shot rifles, I start all my load work .015 off the lands.
What about the ones having magazines? Just asking. lol

[Fuj']

What about the ones having magazines? Just asking. lol

The only rifles I use with magazines are 5.56 auto loaders. My 3 bolt
guns are all single shot. Never needed a bolt gun with a magazine.
Even my wood chuck rifle, I prefer accuracy over capacity. The auto
loaders get a diet of Mag length, IMI 77gr SMK Mod 1's.

[Robinhood]

Darrker, I agree completely. I don't own it and find that I can get where I want to be without QL. Maybe someday I will need QL but not today.

[yobuck]

The only rifles I use with magazines are 5.56 auto loaders. My 3 bolt
guns are all single shot. Never needed a bolt gun with a magazine.
Even my wood chuck rifle, I prefer accuracy over capacity. The auto
loaders get a diet of Mag length, IMI 77gr SMK Mod 1's.
Well i guess my point in asking was that in my experience at least the seating depth dosent (always) make much difference.
I said much difference because it might make at least some, if we were to really get down to the nitty gritty in measuring.
But then does nitty gritty measuring always matter as to our success in what were doing?
Years ago when groundhogs were plentifull in Pa, i knew a few people who would kill a couple hundred each year.
And most of those were at some very impresive distances. These were just regular guys using pretty average equipment.
I think the biggest factor was that they knew what it took to kill lots of groundhogs and thats what they did.
For many years i subscribed to the small magazine put out monthly by the Pa Game Commission called The Pa Game News.
They had regular writers heading up the various subjects, and the one heading up the rifle shooting dept was a guy by name of Don Lewis.
Basically, he had a stash of different articles he would just reuse year after year timed for a particular season.
How to sight in your rifle for example maybe a month before deer season each year.
Ground hogs were a favorites topic of his, and he and his wife Helen shot lots of them.
Of coarse they always ate the ones they shot, because not to do so would be simply destroying an animal for just the enjoyment, which of coarse is wrong. Needless to say he and Helen would be eating them 3 meals a day all year long based on all they shot.
And they did very well on deer also, so go figure. Hopefully they werent ardent fisherman as well.
But what finally ended it all for me and caused me to say enough is enough of the magazine is when Don in writing, stated that any ground hog he killed that wasent hit exactly where he was holding, was considered by him as a miss. Maybe what Don really meant was that he didnt have to eat any of those he missed.lol
But i guess he expected his readers to eat all that BS.

[Fuj']

Never put much faith in the "PA Game News". Wood Chucks, like any
other wild species experience low numbers from time to time. Same for
Perch and walleye out in the lake. Rabbit populations had a severe
decline, and now every every one on the block has one or two. Red
Squirrel's are down, but Greys, and Fox squirrels are doing well, and
even seeing more Black's that really seemed to disappear a few years
back. Wood Chucks are overwhelming strong in numbers at the present,
And stupid as ever.....Getting back to "Off the Lands" I'll be trying a
gizmo on a 6.5 barrel. A barrel tuner. These are not just for the Bench
guy's anymore. If your hampered by magazine length, and just missing
that higher end node you want for hunting, bolt one on and play. It's
only money.....