bhawkeye
03-11-2008, 06:10 AM
Working up loads is something too many people take shortcuts with.
In the last 6-7 months, I've worked up a LOT of loads, many with no published data to work from.
Only constant thru the entire process, is there is no constant.
If you generally start with a mid range load and go from there, you *might* be missing some great shooting, and/or biting off more than you bargained for right outta da box.
Good example, Hodgdon's LongShot data and the 10mm.
8.5-9.5 with a 180 is published.
9.0 is a very stout load with a 180 @ 1.250. Go up another ½ grain from there ? Not without having some experience with LS and the way it behaves on the way up, knowing the characteristics of the brass you're working with and damn sure not without knowing your bullet properties with regard to bearing surface and drag coefficient.
Keep in mind, published data is just a guide, not a be all end all loading recipe, like shotgun data.
Different ambient conditions, bullet profile, bearing surface etc.. will all affect performance.
Published data is put together from a data subset produced in a lab, with little worry of ambient conditions like humidity, temperature, wind or barometric pressure. It is developed with a specific lot of powder, bullet, brass and primer in a specific test barrel (or gun) and interpreted as well as the training of the individual conducting the firing and the instruments allow.
Most of the published data available today is warmed over from initial testing done MANY years ago. As test equipment and methodologies and improve in quality and accuracy, the data has also changed (in most calibers).
While many consider changing headstamp/brand of brass, lot of powder, bullets, lot of primers or even brand of primers to be of minor concern, keep in mind, most of us don't have the luxury of ideal or controlled conditions. Therefore, it is all but impossible to recreate the exact results as outlined in published data.
So, what good is published data ? It is good for use as a simple guide, nothing more. Don't believe that ? Drop 9.0 gr of Longshot in a Hornady case with a plated RN bullet and a Fed primer on a warm day. You *will* see a fps increase from the fps shown in published data. The same bullet, in a Federal case, with a CCI primer, with the same powder charge, fired under the same conditions, in the same gun, will drop FPS seen over a chrono.
All of this doesn't take into account the minute differences in seating depth, powder measure slop, brass thickness or weight variation from one bullet to the next. Hey, they all look the same... right ?
It is very possible, using minimum charge weights, a specific combination of components and conditions can produce a load that is easily capable of generating excess pressure.
Been there, done that, read the book, saw the movie, did the chick - twice, didn't want the t-shirt.
Toss in the variation in test equipment, calibration of test equipment and training level/aptitude of the person interpreting the data and it's easy to see how published data variations occur.
This being said, it can not be stressed enough how important it is to work up a load thoroughly.
After working with a specific powder/primer combination for a while and closely monitoring your results, you can be better prepared to form a reasonably accurate expectation of behavior of a given combination. This isn't to be construed as 'knowing' anything, just the ability to recognize/reproduce similar results.
With this in mind, when working up loads, I usually make up 30 loads, using the same powder/brass/primer/bullet and charge weight. I make up groups of 30 rounds increasing powder charge in .1 increments. I'll shoot 10 on a morning trip to the range of a starting charge weight, then move up to the next charge weight, eventually working over the range I've loaded. Next trip to the range, I will shoot at the hottest part of the day and keep meticulous notes of chrono data and any abnormal signs while noting accuracy results, time of day, temp and a short note about the way the load shoots with regard to soot, recoil etc.. I keep the last 10 rounds with my notes until I find a happy medium for the range of conditions I shoot in, with that specific set of components.
Swap brass, primers, bullets, lot numbers of powder or primers and it's a new batch, recorded seperately, and the work starts over again.
I routinely start beginning loads under published charge levels with most powders. H110/296 being an exception that immediately comes to mind.
After gathering data for a while, it's reasonably easy to plot the data and see a recurring characterisitic (if one exists). This can help quite a bit with future load development for the gun used for load development.
Change guns, start the process over again.
After working with several powder/primer/brass combinations, it's pretty easy to see some powders are MUCH more forgiving than others. Among the most forgiving is AA#5, the least, LongShot and H110. No rhyme or reason, AA 1680, HS-6 and straight Clays.
Working up loads is more than getting a bullet out of the tube. It is developing an understanding of the characteristics of component combinations, the effect ambient condition change and accuracy gained or loss with the manipulation of the things we can control.
The task at hand, is to gain this understanding safely, without injuring yourself, or others, or damaging your weapon.
Starting with mid-range published data on any load without a thorough understanding of the characteristics of the behavior/performance of the chosen combination is no different than a fun time with a game of Russian Roulette.
You might be incredibly lucky, but sooner or later, odds are, it's gonna bite you in the ass.
Plus, you may never trip over the best load you ever fired doing it that way.
For real
Word. :)
In the last 6-7 months, I've worked up a LOT of loads, many with no published data to work from.
Only constant thru the entire process, is there is no constant.
If you generally start with a mid range load and go from there, you *might* be missing some great shooting, and/or biting off more than you bargained for right outta da box.
Good example, Hodgdon's LongShot data and the 10mm.
8.5-9.5 with a 180 is published.
9.0 is a very stout load with a 180 @ 1.250. Go up another ½ grain from there ? Not without having some experience with LS and the way it behaves on the way up, knowing the characteristics of the brass you're working with and damn sure not without knowing your bullet properties with regard to bearing surface and drag coefficient.
Keep in mind, published data is just a guide, not a be all end all loading recipe, like shotgun data.
Different ambient conditions, bullet profile, bearing surface etc.. will all affect performance.
Published data is put together from a data subset produced in a lab, with little worry of ambient conditions like humidity, temperature, wind or barometric pressure. It is developed with a specific lot of powder, bullet, brass and primer in a specific test barrel (or gun) and interpreted as well as the training of the individual conducting the firing and the instruments allow.
Most of the published data available today is warmed over from initial testing done MANY years ago. As test equipment and methodologies and improve in quality and accuracy, the data has also changed (in most calibers).
While many consider changing headstamp/brand of brass, lot of powder, bullets, lot of primers or even brand of primers to be of minor concern, keep in mind, most of us don't have the luxury of ideal or controlled conditions. Therefore, it is all but impossible to recreate the exact results as outlined in published data.
So, what good is published data ? It is good for use as a simple guide, nothing more. Don't believe that ? Drop 9.0 gr of Longshot in a Hornady case with a plated RN bullet and a Fed primer on a warm day. You *will* see a fps increase from the fps shown in published data. The same bullet, in a Federal case, with a CCI primer, with the same powder charge, fired under the same conditions, in the same gun, will drop FPS seen over a chrono.
All of this doesn't take into account the minute differences in seating depth, powder measure slop, brass thickness or weight variation from one bullet to the next. Hey, they all look the same... right ?
It is very possible, using minimum charge weights, a specific combination of components and conditions can produce a load that is easily capable of generating excess pressure.
Been there, done that, read the book, saw the movie, did the chick - twice, didn't want the t-shirt.
Toss in the variation in test equipment, calibration of test equipment and training level/aptitude of the person interpreting the data and it's easy to see how published data variations occur.
This being said, it can not be stressed enough how important it is to work up a load thoroughly.
After working with a specific powder/primer combination for a while and closely monitoring your results, you can be better prepared to form a reasonably accurate expectation of behavior of a given combination. This isn't to be construed as 'knowing' anything, just the ability to recognize/reproduce similar results.
With this in mind, when working up loads, I usually make up 30 loads, using the same powder/brass/primer/bullet and charge weight. I make up groups of 30 rounds increasing powder charge in .1 increments. I'll shoot 10 on a morning trip to the range of a starting charge weight, then move up to the next charge weight, eventually working over the range I've loaded. Next trip to the range, I will shoot at the hottest part of the day and keep meticulous notes of chrono data and any abnormal signs while noting accuracy results, time of day, temp and a short note about the way the load shoots with regard to soot, recoil etc.. I keep the last 10 rounds with my notes until I find a happy medium for the range of conditions I shoot in, with that specific set of components.
Swap brass, primers, bullets, lot numbers of powder or primers and it's a new batch, recorded seperately, and the work starts over again.
I routinely start beginning loads under published charge levels with most powders. H110/296 being an exception that immediately comes to mind.
After gathering data for a while, it's reasonably easy to plot the data and see a recurring characterisitic (if one exists). This can help quite a bit with future load development for the gun used for load development.
Change guns, start the process over again.
After working with several powder/primer/brass combinations, it's pretty easy to see some powders are MUCH more forgiving than others. Among the most forgiving is AA#5, the least, LongShot and H110. No rhyme or reason, AA 1680, HS-6 and straight Clays.
Working up loads is more than getting a bullet out of the tube. It is developing an understanding of the characteristics of component combinations, the effect ambient condition change and accuracy gained or loss with the manipulation of the things we can control.
The task at hand, is to gain this understanding safely, without injuring yourself, or others, or damaging your weapon.
Starting with mid-range published data on any load without a thorough understanding of the characteristics of the behavior/performance of the chosen combination is no different than a fun time with a game of Russian Roulette.
You might be incredibly lucky, but sooner or later, odds are, it's gonna bite you in the ass.
Plus, you may never trip over the best load you ever fired doing it that way.
For real
Word. :)