Check this out: The difference of 1/10th of a grain.


.41 magnum man
August 3, 2007, 02:11 AM
Okay, I am shooting a .41 magnum. My components are: 2400 powder, 210 grain Hornady xtp bullets, Winchester brass, and Winchester primers.

So I load up 6 bullets at what I thougt was 17.6 grains of powder, but after loading them I realize I am off 1/10 and actually loaded 17.5 I figure that can't be a big deal. So I shoot the six rounds, open sights with a rest, and I shoot a group I can cover with the end of my thumb at 12 yards. Hey, I like it. So I go back and load 12 more, but I alter the load to 17.6 grains which is what the book called for. So I go back out and shoot 6 and I cannot believe the difference. Bullets going everywhere in a 2x3 inch or so area. I decide to wait awhile before I shoot some more. Maybe I am tired. So I come back a couple hours later and shoot 6 more rounds. I get the same crappie group. Well I go back and load up 6 more, reducing the load again by 1/10th to 17.5 Guess what? The group tightened back up again. I got the pictures to show you below:

I guess I am really lucky that I was off the 1/10 or I'd still be trying to find the right load! As you can see in the pictures, I did load up a hotter round of 19.2 grain, and shot those 6 with results a little better than the 17.6

I guess 17.5 is it. Should I try 17.4?

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August 3, 2007, 02:29 AM
One thing some people consider when loading for handguns is finding a load that works well AND where a 1/10 grain plus or minus doesn't make much difference.

People do this so they can throw charges plus/minus and get good results - it's easier than weighing every charge which is pretty much necessary when a single 1/10 makes a big difference.

August 3, 2007, 03:16 AM
I guess 17.5 is it. Should I try 17.4?It ain't broke.
People do this so they can throw charges plus/minus and get good results - it's easier than weighing every charge which is pretty much necessary when a single 1/10 makes a big difference.A well-adjusted powder drop is a wonderful thing :D

August 3, 2007, 07:17 AM
That's the thing about 2400, it flows through powder measures very consistantly, if you have good luck at 17.5, use 17.5....

When I used 17.6, it was with CCI magnum primers, so even the smallest substitution makes a difference.....

August 3, 2007, 09:25 AM
I think your shooting may be as much to blame/praise for the groups as the 1/10 grain. You have a fairly good technique but seem like you relax and pull one off. You should shoot at a measured range like 50 feet and learn to get them all in the same group.

August 3, 2007, 09:34 AM
I can see how that would apply to pistol, since you are dealing with powders that burn faster.

I wonder if that applies to rifle as well. I usually stay within +/- .1 grain just because it's easier to not have to do minute adjustments when you load a lot of rounds.

August 3, 2007, 02:18 PM
To do an accurate assessment you really need to bench that handgun. Anything else and it might be all in your mind. I'm not questioning your technique, but sometimes the mind can be a powerful thing.

August 3, 2007, 03:49 PM
I'll load .1 grain increments and test a few of each for signs of excessive pressure. After that I'll do 2 sets of 5 shot groups each. My wife gives them to me semi-randomly (making sure not to give me the same twice in a row) so I don't know which one I am shooting.

August 3, 2007, 04:31 PM
I do not think 1/10th of a grain of powder would make any perceptible difference in accuracy for a handgun round at normal handgun ranges. I don't know what kind of powder dispenser you are using, but I have used a Lee Pro Aut Disk and RCBS Uniflow. Both of these will throw +/- 0.1 grains, but certainly neither will always throw the exact same weight to 1/10th of a grain. When I want that kind of precision, I weigh manually. How do you know all your rounds were 17.5g? Did you hand weigh each one?

I think you need to test this more. Load up some at 17.5g, and some at 17.6 grains. Then blind yourself to which is which, and shoot from a bench. See if it makes a difference when you don't know which you are shooting.

I don't want to just dismiss this as being all in your mind, but I bet that has something to do with it. Either that, or luck.

August 3, 2007, 09:29 PM
I think the first group looks good. Fire more rounds off and see if you can duplicate the results consistantly. You did a smart thing by using a rest (it seems like some people did not read that part). Lots of people make the mistake and just assume its the charge or components that are giving them large groups. Keeping things as consistant as possible makes for a more accurate assesment. Keep up the good work and have fun trying new things. I think the best part of reloading is the search for that perfect round (for me at least it will always be that elusive beast)...

Mal H
August 3, 2007, 10:47 PM
Stinger - he said he used a rest, otherwise I'd agree with you. Sometimes reloading is full of self-fullfilling prophecies (or expectations).

.41 MM - looks like you found just the right load. But, I'll be honest, I've never seen .1 grains of a relatively slow powder make that much difference in a grouping as long as the load is within a reasonable range.

August 3, 2007, 11:14 PM
"...Should I try 17.4?..." Did you work up the load or just pick one? You really should begin with the 'Starting' load and work up to the max load.
"...a group I can cover with the end of my thumb..." Mind you, that'll do if all your shots are at 12 yards.

.41 magnum man
August 4, 2007, 02:08 AM
Well, what I did was I measured each and every load on my Lee Scales by hand. I measure out the amount, then pour it into a little glass tube and put a cap on it. I have 12 of these glass tubes, and I do 6 or 12 at a time. After I do that, I begin loading my cases. I uncap a glass tube with the premeasured dose, put it in the case, set the tube aside and finish that load. Then I do it all over. It is a safe way to do it because I can see through the tube and know immediately if I double charged before it goes into the case. It makes the reloading sequence a little faster and methodical because I already have it premeasured, and can just move along with up to 12 rounds. Then I have to re-measure some more. The auto powder measure seems nice, but I don't know how to use the thing yet. Besides, I figure it is better to learn something conventionally first. You understand more about it.

Now the way I did my loads and maybe I misunderstood what it means by working up from the minimum to the max. I didn't start with the minimum and work my way up 1/10 of a grain at a time. Nothing or nobody ever explained it that way to me. I just started at the minimum listed, and then went up to the next load listed. Everyone says, go by the book, so I did. I strictly went by the book. I did not do any load that was not listed in the book.

My book has the minimum listed at 16 gr. (I think that is the number, I don't have the book here) Anyway, I loaded up some shells at that load. The next thing listed is 16.9, I think. So I did that. Then it lists 17.6, so I did that. But on that load I had the scale set on 17.5 instead of 17.6 by accident. It can be hard to see those little marks, you know! Using a REST, I shot those six. Well, in that group every hole was touching, and two holes were so close it was almost one. After the first group with the 17.5 I realized my mistake (if you want to call it that) and set the scale at 17.6. I made up 12 rounds. I shot 6 and they went crazy compared to the first batch. I thought it might possibly be me, so I quit for awhile. I came back a couple hours later and shot the other six 17.6's They did not group together either. So I reloaded 12 more 17.5's to see if there was a difference. I shot twice free handed just for fun. I put one in the bullseye, and 1 about 1/2 inch away from that. Yes, that could have been luck. But then I RESTED my gun again and fired 6 more. Except for the one that I pulled off on, the other five grouped together like the first set of 17.5's did. ALL SHOTS were at 12 yards. When I pulled off on the one shot, I knew I did it even before the gun went off. So it wasn't the load on that one, it was me. I can see accidently hitting something with one bullet, but to have both sets (12 shots all total except the one I pulled) of 17.5's in such close groups is not an accident.

I loaded up some at 19.2 and shot 6 of those. The group was better than the 17.6's , but not close to the 17.5 grain loads.

Now this evening I shot with a REST twice at the center of a box at 35 yards. Both were within 1 inch of each other just a hair high of dead center. I then went back to 57 yards. (I didn't know it was 57 yards until I ranged it with a range finder after I shot. I just backed up a ways, took a REST and shot. Now both of those bullets hit high and to the left about 6 inches, and they were about 1 1/2" from each other. The group was okay, but way off from the other group. Don't know what did that. Might be at that distance I am pulling and can't tell it, though I must pull the same every time. I'll have to play with that some more and see what happens.

Mal H, that the 1/10th of a gr. made that much difference is a surprise to me too, and you have to remember, I am new at reloading, so I didn't have a clue. I figured it would not matter, and that is why I reset the scales 1/10 higher back to what the book called for. Not for the difference sake, but to be doing what the book said.

RC, I am definately having fun! And it is the accuracy that I am shooting for. When I can shoot all the bullets into the same bullet hole, then I know I have it as good as it gets. A friend of mine has a scoped Contender in 7-30 Waters and he has his reloads just right. We aim at a pop bottle top and shoot it down to nothing. I can put all my shots in a 3/8 to 1/2" group at 25 yards. He can shoot all of them through the same bullet hole! I hate him. :D

Now shooting the different loads not knowing which were being shot would be interesting, but I don't see how it really helps. I don't think I am subconsiously hoping the 1/10th grain lower bullet will do better than the higher, so I purposely hold better for one set of loads than I would for the others. Then again, each person has to understand how they think about things and do accordingly. My brain just doesn't work that way. I hold aim the best I can for every shot regardless of the load or the situation. If I don't do that, then why fool with it? What I have to watch out for is if I get to playing games then I will lose track of what I am shooting and have to start over again. No, I'd rather know which is which and keep an accurate account of it. But that is just me, understand.

But now, I have run out of bullets and primers, and I can't get anymore until late next week. I have about 12 loads left, but I am keeping them for emergency use until I get the new stuff. You never know, I might have to shoot a ferocious groundhog, or an over zealous squirrel or something. :)

Marlin 45 carbine
August 4, 2007, 11:40 AM
I had a similar experience with my BDA 380 but with 3/10th gr and different cases(brass) - a noticeable tighter group. same primer, powder and bullet. the 'good' load is on the low end of the charge weight specs.

August 5, 2007, 10:11 AM
.41Mag Man,

The publishers don't intend that you use the load data verbatim, creating loads for each and every printed load charge, and only creating loads with the listed charges. Doing so would actually be rather dangerous.

Experienced reloaders use mutliple load data sources to corroborate agreement in min/max numbers - and if they don't agree, it requires researching the discrepancy. Otherwise, if max numbers are similar, you can pick any of them as a THEORETICAL maximum to work up to. Working up to max is described later below.

Its not feasible or helpful for load manuals to list every charge in .1gr increments between the min and max charge, so the publishers decide on a reasonable number of in-between points to list, to give users a general concept of pressure and velocity change characteristics. Sometimes the better publishers choose data points which reflect significant changes in the pressure/velocity curves.

If the book lists 4 charges, from min to max for your caliber, it is very dangerous to simply load test with only those 4 charges. These are guides for your own determination of starting and ending parameters in your series of loads to create for testing. Very methodical loaders will start near minimum, and for a listed max of for instance, 20gr., will increment by .3 or .4gr, and when reaching the 90% point, switch to smaller increments of .2gr to ensure a cautious approach to the gun's particular max charge. People less patient may choose a start point in the middle of the min/max range - that's okay, but they might miss a sweet, light accurate target load. As no two books give the exact same max charge for any load combination (due to variations in testing equipment, components, and test firearms), its not uncommon to go slightly above published maximums, as long as you take this kind of incremental approach and check for pressure signs from each load.

You don't want to arbitrarily jump between the last two numbers you see on the chart, which in your case is a whopping and scary 9% increase at the high end.

As far as the .1gr making a huge difference on a 17gr load - its a personal phenomenon. The laws of physics and ballistics are pretty hard to change. Trust us when we say it was a fluke. You can make several sequenced batches between 17.0 and 18.0 in .1gr increments. Make at least 4 batches of this sequence, and bench fire them, one seqeunce-batch for each range trip to take fatigue out of the factor. You will see a pattern, but it won't be a repeat of your first experience. Going thru the trouble of doing this will give you a better understanding of the relationship between the charge weights and terminal performance.

I'm no expert in reloading ballistics, but the concepts I've conveyed is what I've read in a number of journals, books, mags, and forums. The more I learn, the more I find I don't know. Still, its fun. Enjoy this new hobby and keep asking questions. Good luck.

.41 magnum man
August 6, 2007, 09:21 AM
PsycoKnight, that was a great explanation! I realize I was confused on "going by the book." Although I did try out the next to the highest max
(19.2) load in the book, if I were to try the max, I was going to "sneak up on it." But maybe I should have inched up to the 19.2 also.
I see your point and it is well taken. Thanks for helping me out with that. I guess it was just a miracle I hit a sweet spot the way I was doing it.

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