How to work up a load

[greenshovel]

OK here is my first NEWB question.

Equipment; 7mm STW - Nosler Accubonds 160gr - H-1000

When working up a load for the above round do you guys, load five to ten at a certain powder grain (lowest to highest) then choose the tightest group and then play around with bullet seating until you get the tightest shot group?

I am new to reloading so be gentle :mrgreen: and thanks for all the help.

 

[DrMike]

Gentle! Jump in! Spend money! Enjoy the madness! Seriously, when testing a particular load, I'll make a spread of charges, three each covering from the minimum to the maximum. If the case is a magnum, I'll allow for some larger differentials in powder charge; if case volume is less, I'll use a smaller range of powder charge. Depending on the burn rate, I'll vary by no more than 2% between charges. If the projected velocity differential is reasonably great, then the charge difference will be much smaller. If the projected velocity differential is fairly small, I'll make the charge differential somewhat larger. In the case you propose, I'd likely alter charges by about one grain, or no more than 1.5 grains. Since you are using a cup and core bullet (despite being bonded), I would choose a standard COAL to begin. This will be determined by either the magazine, or if the magazine allows, I will load 0.010 inches off the lands. I will shoot these, running them across the chronograph, beginning with the lowest charge and working upward toward the highest charge, always watching for pressure signs and observing accuracy. I pay especial attention to the standard deviations. While three rounds isn't enough to make a definitive statement concerning accuracy, it will be suggestive, especially when you are able to discern a pattern across the spectrum of loads. Should one charge stand out with good velocity and reasonable accuracy potential, I will likely load up another set of at the charge to be tested, seating at varying depths. I will vary by about 0.040 inches from the initial COAL, going so much as 0.120 inches from the lands. One of these loads will stand out for accuracy, usually being quite pronounced as it will be approximating the harmonic node. Now, I can begin to fine tune the load, playing with incremental adjustment to COAL and loading up a set of ten to test for accuracy.

 

[greenshovel]

Gentle! Jump in! Spend money! Enjoy the madness! Seriously, when testing a particular load, I'll make a spread of charges, three each covering from the minimum to the maximum. If the case is a magnum, I'll allow for some larger differentials in powder charge; if case volume is less, I'll use a smaller range of powder charge. Depending on the burn rate, I'll vary by no more than 2% between charges. If the projected velocity differential is reasonably great, then the charge difference will be much smaller. If the projected velocity differential is fairly small, I'll make the charge differential somewhat larger. In the case you propose, I'd likely alter charges by about one grain, or no more than 1.5 grains. Since you are using a cup and core bullet (despite being bonded), I would choose a standard COAL to begin. This will be determined by either the magazine, or if the magazine allows, I will load 0.010 inches off the lands. I will shoot these, running them across the chronograph, beginning with the lowest charge and working upward toward the highest charge, always watching for pressure signs and observing accuracy. I pay especial attention to the standard deviations. While three rounds isn't enough to make a definitive statement concerning accuracy, it will be suggestive, especially when you are able to discern a pattern across the spectrum of loads. Should one charge stand out with good velocity and reasonable accuracy potential, I will likely load up another set of at the charge to be tested, seating at varying depths. I will vary by about 0.040 inches from the initial COAL, going so much as 0.120 inches from the lands. One of these loads will stand out for accuracy, usually being quite pronounced as it will be approximating the harmonic node. Now, I can begin to fine tune the load, playing with incremental adjustment to COAL and loading up a set of ten to test for accuracy.

Thanks Mike that was exactly what I was looking for. My crony should be here by the end of next wee. I have a friend that is going to show me how to get the COAL of the lands hopefully within a few weeks. I also posted this morning a reply to your question about my user name in my first thread. :mrgreen:

 

[1Shot]

I do a lot of what is posted above if my short cut that I will tell you about does not work out.
SHORT CUT = Go to the Sierra manual find the caliber and bullet weight you are working with and look at their suggested accuracy and hunting loads. Most of the time these are spot on. Saves a lot of money and time. :mrgreen:

 

[DrMike]

The reason for working up a load is that different reamers cut to different dimensions, different barrels have bores differing by small amounts, throats are cut to differing depths, etc. Lot-to-lot variation in case thickness, powder burn rates and even primer brisance all combine to make it impossible to guarantee that a maximum charge will be safe in every rifle. The 5th Edition Sierra Manual answers the following question: Will the maximum load the you show in your manual be OK in my rifle? with this answer:

"Probably...but perhaps not. Loads that are shown to be below "Maximum" in our test rifles may prove to be too hot in your particular firearm. It is important to understand that maximums vary with several factors, such as temperature, even within the same gun. That load you worked up last fall may be more than a bit rough on your primer pockets when summer rolls around. Ask any prairie dog hunter who has had to shade his gun, put his cartridges on ice, and avoid leaving a loaded round in a hot chamber too long. Now, take into consideration variations in components. This powder may be the same brand and type, but is slightly different in burning rate than the last lot you used. Your cases may vary within the same brand as to both volume and strength. Guns can vary dramatically from one another in internal dimensions. A short throat, a tight bore, and a host of other internal variables may combine to create substantial differences even between two guns of the same make, model and chambering. HEED OUR ADVICE: START LOW AND WORK UP YOUR LOAD CAREFULLY!" (Sierra Rifle & Handgun Reloading Data, V, pg. 25).

 

[greenshovel]

Thanks Mike, I plan on starting at the lowest load and work it up by a grain at a time as you mention. Thanks. :mrgreen:

 

[DrMike]

I don't know of a reputable bullet or powder manufacturer or distributor that produces hand loading guides that would advocate picking a charge and shooting. All insist on working up a load from a safe minimum. Some will argue that they "know" their rifle and they can therefore avoid the workup. However, they have no control over the manufacturing of components, which changes the game significantly. Powder can vary in burn rate as much as ten percent lot-to-lot. That can be a real game changer at maximum charge. It is a good practise to maintain sensible habits in hand loading.

 

[C.Smith]

You have been given good advise. I went 15 years of reloading and never had a problem working all my rifles up to a max charge which would lead me think it was would not be a big thing to skip some of that reloading. Well last year I loaded up some new to me bullets and thought about skipping some of the steps but ended up not doing that, glad I did not. Before even reaching a mid level load I hit the max in that rifle with hard bolt lift and obviose extractor marks on the rim of the case (bad signs). Had I skipped to where I had though I would before I would have been over this load and who knows what would have happend. It was a great lesson for me.

Good luck.

Corey

 

[ScreaminEagle]

I usually load five rounds each of all the powder/bullet combos I wanna test. i take the top one and go from there. five rounds each in increments of .5 grains. When I find best load without pressure signs, then I play with seating depths in increments of 10 thousands. Then neck tension etc. It takes awhile to find the "perfect load", but it is always worth it!

 

[jmad_81]

When I had my 338 Edge (338-300RUM) I worked in 1 grain increments, but I was using between 99 and 102 grains of powder. For everything else I use .5 grain increments. I usually start at the books middle load. On a few guns, the middle eneded up being pretty close to the max in those guns. A Chronograph is a reloaders best buddy. You will learn what you didn't know, and a bunch more my seeing how fast you are pushing your bullets. I have also found that some guns react very different to tweaking of the COAL. My 270 WSM Loaded .020" off the lands will handle 71 gr of RL-25 pretty easy @ 3174 fps. Back them off the .060" off the lands and that same load is over 3300, and doesn't shoot near as well. On the other hand My STW with Retumbo seems to get slower the farther I get off the lands. When I went from .060" off to .065" off I lost 15 fps, and my ES and SD got worse. My brother (ATM here) did several load tests in his Savage 284, and he also found that he was loosing FPS the shorter he made his ammo. My 338 WM gets faster the closer the the lands I get. Every rifle is different, and a chrony sure helps figure things out.

On a side note, Let me know how the H1000 works out for you in the STW. I'm shooting Retumbo in mine with the 160 AB and am getting around 3260 with the 160 AB. Retumbo is the only powder I have tried, but I have also heard great things about H1000, 7828, and RL-25.

 

[Coyote Hunter]

“When working up a load for the above round do you guys, load five to ten at a certain powder grain (lowest to highest) then choose the tightest group and then play around with bullet seating until you get the tightest shot group?

It used to be I would load 2-3 at the starting charge, 4-5 in the middle weights and taper back off to 2-3 for the max charge weights. When I started using more expensive bullets I found this was a waste of my money.

What I do now is load 1 at each powder charge (usually 0.5 grain increments) and shoot them over a chrono, recording the charge weight, velocity and point of impact. (When I see pressure signs I stop and the remaining loads get disassembled.) After shooting the development loads, I check the target and look for a tight group of sequential loads. If I find one, it suggests a ‘sweet spot’ that isn’t particularly sensitive to minor variations in charge weight. I’ll select a charge weight in the center of the ‘sweet spot’ and build a few more for testing. This method has dramatically cut down my development time as well as costs.

I highly recommend you get a chrono. The shooting Chrony models are not very expensive and you used to be able to buy refurbs for under $60. Been using mine for years now. I also suggest you get one with a remote readout/control. With the Shooting Chrony models this is the expensive part – the rest can (or could a couple years back) be purchased for $37

 

[greenshovel]

When I had my 338 Edge (338-300RUM) I worked in 1 grain increments, but I was using between 99 and 102 grains of powder. For everything else I use .5 grain increments. I usually start at the books middle load. On a few guns, the middle eneded up being pretty close to the max in those guns. A Chronograph is a reloaders best buddy. You will learn what you didn't know, and a bunch more my seeing how fast you are pushing your bullets. I have also found that some guns react very different to tweaking of the COAL. My 270 WSM Loaded .020" off the lands will handle 71 gr of RL-25 pretty easy @ 3174 fps. Back them off the .060" off the lands and that same load is over 3300, and doesn't shoot near as well. On the other hand My STW with Retumbo seems to get slower the farther I get off the lands. When I went from .060" off to .065" off I lost 15 fps, and my ES and SD got worse. My brother (ATM here) did several load tests in his Savage 284, and he also found that he was loosing FPS the shorter he made his ammo. My 338 WM gets faster the closer the the lands I get. Every rifle is different, and a chrony sure helps figure things out.

On a side note, Let me know how the H1000 works out for you in the STW. I'm shooting Retumbo in mine with the 160 AB and am getting around 3260 with the 160 AB. Retumbo is the only powder I have tried, but I have also heard great things about H1000, 7828, and RL-25.

jmad, will do thanks for the information

“When working up a load for the above round do you guys, load five to ten at a certain powder grain (lowest to highest) then choose the tightest group and then play around with bullet seating until you get the tightest shot group?

It used to be I would load 2-3 at the starting charge, 4-5 in the middle weights and taper back off to 2-3 for the max charge weights. When I started using more expensive bullets I found this was a waste of my money.

What I do now is load 1 at each powder charge (usually 0.5 grain increments) and shoot them over a chrono, recording the charge weight, velocity and point of impact. (When I see pressure signs I stop and the remaining loads get disassembled.) After shooting the development loads, I check the target and look for a tight group of sequential loads. If I find one, it suggests a ‘sweet spot’ that isn’t particularly sensitive to minor variations in charge weight. I’ll select a charge weight in the center of the ‘sweet spot’ and build a few more for testing. This method has dramatically cut down my development time as well as costs.

I highly recommend you get a chrono. The shooting Chrony models are not very expensive and you used to be able to buy refurbs for under $60. Been using mine for years now. I also suggest you get one with a remote readout/control. With the Shooting Chrony models this is the expensive part – the rest can (or could a couple years back) be purchased for $37

Yote Hunter, I ordered a crono yesterday :grin: I like the idea of shooting one at each grain to figure out were one needs to stop. Thanks :!:

 

[greenshovel]

You have been given good advise. I went 15 years of reloading and never had a problem working all my rifles up to a max charge which would lead me think it was would not be a big thing to skip some of that reloading. Well last year I loaded up some new to me bullets and thought about skipping some of the steps but ended up not doing that, glad I did not. Before even reaching a mid level load I hit the max in that rifle with hard bolt lift and obviose extractor marks on the rim of the case (bad signs). Had I skipped to where I had though I would before I would have been over this load and who knows what would have happend. It was a great lesson for me.

Good luck.

Corey

Thanks Corey, :shock: thats a lesson that I do not want to learn!

 

[DaveA37]

Dr. Mike ...."Probably...but perhaps not. Loads that are shown to be below "Maximum" in our test rifles may prove to be too hot in your particular firearm. It is important to understand that maximums vary with several factors, such as temperature, even within the same gun. That load you worked up last fall may be more than a bit rough on your primer pockets when summer rolls around. Ask any prairie dog hunter who has had to shade his gun, put his cartridges on ice, and avoid leaving a loaded round in a hot chamber too long. Now, take into consideration variations in components. This powder may be the same brand and type, but is slightly different in burning rate than the last lot you used. Your cases may vary within the same brand as to both volume and strength. Guns can vary dramatically from one another in internal dimensions. A short throat, a tight bore, and a host of other internal variables may combine to create substantial differences even between two guns of the same make, model and chambering. HEED OUR ADVICE: START LOW AND WORK UP YOUR LOAD CAREFULLY!" (Sierra Rifle & Handgun Reloading Data, V, pg. 25).


With all those variables, how does anyone ever get a correct load (for any particular rifle) WITHOUT spending a fortune. As most of know, when you change more than one variable at a time, you can't be certain which variable makes/made the difference at the end. There has got to be a happy medium there someplace. (Just my opinion, I'm not trying to start any debate or contradict your expertise, which is obviously 100 times better than my own. Just sayin) :mrgreen]

 

[DrMike]

Dave,

The quotation was an exact quote from the Sierra manual, primarily because a poster had specifically stated that he accepted the accuracy load suggested by the Sierra staff for a given weight of bullet.

This does bring up a matter of which the hand loader should be aware--different bullets will have differing bearing surfaces, and a person can get into trouble in a hurry. I worked up a load in a lever gun (many years ago). I had used a "cheaper" bullet of a particular weight, and verified that I had a safe load. I changed to a more robust bullet because I wanted to use it for hunting. To my credit, I dropped back in charge about 5%. When I touched off that first round, the lever slapped down so hard it broke my finger, and the velocity was very high. The case was torn in two. Fortunately, the chamber was not bulged. I used that rifle for hunting for many years after, taking many head of game. In fact, even with a 5% reduction in charge, due to the increased bearing surface and the difference in metals used in the jacket, the bullet I was testing generated very high pressures Ultimately, I proved that the bullet I wanted to use would work just fine, but the maximum charge was almost 10% less than that for a safe maximum with the first bullet.

I seldom invest more than nine shots to determine a safe load. I will know very quickly whether the load is worth investigating more carefully or not. I have often cautioned people that hand loading will not likely save them money, but it will provide hours of enjoyment, make them a better shot and allow them to craft a load that is specific for their own rifle. It is doubtful that we will get more velocity than factory ammunition, but we can usually build more accurate ammunition. One matter that would help many hand loaders is to be realistic about their rifle and their own abilities. For hunting, a rifle that will shoot a 1.5 inch group at 100 yards from field position will put the bullet in the kill zone for most ungulates to well beyond 400 yards. Few of us want to brag that we shoot 1.5 inch groups with our hunting rifle, however. We shoot from the bench to prove what the rifle is capable of doing, but we shoot from field position to prove what we are capable of doing with the load we have built.

 

[Guest]

I work very similarly to Dr. Mike. In the case of the 7mmSTW, I'd strongly recommend the 2% rule to avoid too many test loads. I like to start low, and work up in 2% increments, loading three of each. I shoot my workups over a chronograph, as I want all the info I can get about the loads. I inspect each case upon removal from the chamber, to check for ejector marks, primer conditions, and neck conditions. If I see pressure issues, I stop there. I evaluate what I'm seeing back at the loading bench, and most of the time end up pulling down the remaining load workups and recovering the components. The best charge weight, considering velocity, SD, ES, and group size, gets rebuilt in various seating depths, much like Dr. Mike. I search for the ideal seating depth much the same as Dr. Mike, as well.

In reality, one can get overwhelmed with the infinite variations in combinations and possibilities, but it's helpful to remember that you should just be pursuing the shortest path to good loads, which is to pick a suitable powder you believe has a good chance of working well, and then chase the details. Or maybe a couple of powders (I frequently do this) and pick the one that performs best. Then tweak seating depth. There is no guarantee you've found the very best load for your rifle, but if you find something consistent and accurate, you're all set.

In your 7mmSTW, 2% is going to be about 1.5gr. If the max charge were 80gr of powder X, I'd back down at least 4 increments (8%) and start at 74gr. Three at 74, three at 75.5, three at 78.5, and three at 80gr. Then shoot them in order, over a chronograph, and look for pressure signs. When you're at home, review the velocity data (you did write it down in your range notes, didn't you?) and compare that to groups, if you like. I generally don't think of these groups as the be-all, end-all of what the rifle will do, but rather a nice indicator of what direction I should take. If 78.5gr shows the best potential, and velocity is good (and 80gr is worse enough to make 78.5 the best choice) I'd start with that, and tweak seating depth.

I can say I like the idea of a single round at smaller charge steps as an initial workup. I've got a couple of rifles about to get their first workups, and I may try that with one of them. I don't know that it would save a bunch, but every penny counts, in today's economy!

 

[widgeon]

Sage advice, DrMike. On all counts.

 

[nvbroncrider]

Like has been said here be cautious and pay attention to detail. I personally like to work up in .5 gr increments. After each shot I check the brass for signs of pressure. Fire one extract, take 3 minutes check brass, fire one repeat and compare. Looking for ejector marks flat primers sticky bolts. Then I look at the target and generally you will see a vertical string do to each charge will change in velocity and POI. When I see a set of charges that are close to same POI I then take those and load 3 shots each and then shoot groups for accuracy.

 

[hardpan]

Some great advice here. Here could be a shortcut. I will buy a box of high quality factory ammo. The highest priced so far is WBY at 69 a box. I will shoot it, once the barrel is broken in, and test it using my chrono. If it shoots well, I will check the velocity of the load against the book to see which powders and loads get me close. i start below those loads following advice similar to that given by Dr Mike.

If it does not shoot well, I do end up with 20 pieces of brass. But so far, I have found very good groups starting with this process.
Hardpan

 

[GSSP]

This is the best and most comprehensive article i've read on developing a load, especially for LR. If you don't have a range that will stretch out to 1000 yds, tone it down a bit and do the best you can. I surely wouldn't try any of this at less than 300 yds. This article has changed the way, for the better, on how I develop a load. Your 7STW is meant to breath WAY out their and this will allow it.

http://www.accurateshooter.com/technica ... velopment/

Coloring the bullet ogives with different markers is brilliant. I have settled on 4-5 different colors; no color, green, medium blue, red and black. I shoot them in that order too and just repeat if I have, say an 8-10 shot string, increasing in powder charge each shot.