Tell Me About Using Fractions of a Grain In Load Development

[Chief TC]

I have been reloading for awhile but far from experienced. Still have a lot of hours to put in and more calibers to reload before I can feel I am experienced. I use loading manuals and reloading data sheets from powder companies but I am perplexed about how I should approach increasing or decreasing loads by .1 or .2, etc. As an example, let's say a range of 47.1 to 50.4 is given for a starting load and max load. How would you go about load development and how would you determine if you needed to change a load by .2 or .3 or .6, etc? I typically work in trying different loads in whole grains and I select the load that performs the best based on reloading data. I've never tried to see if changing +or -0.5 g would make a difference. FYI - I don't compete or focus on precision rifle, so I am not chasing sub-moa. My hunting rifle is a Rem 721 and shoots factory loads sub-moa which is all I need for my purposes. Thanks in advance for sharing your experiences.

 

[Charlie98]

It depends on a lot of things. Rifle or pistol? What type of powder? What do you expect out of the specific handload?

In Magnum-level handgun cartridges, with big charges of slower burning powder, a .5grn change can be a reasonable step, not so much in a small auto case like the 9mm or .380. There are some powders, TiteGroup, for example, where the entire range of data might only be 1grn... so baby steps are required, there. My 9mm TiteGroup ladders are in .2grn increments, for example.

As I mentioned, some powders have greater charge weight range than some other powders. Big, bulky powders may be ultimately limited to case fill, for example.

For my rifle blasting ammos, in .308, my charge weights are round numbers... 41.5grn, 42grn, 42.5grn... and so on. In my cast rifle cartridges... I use the same basic steps, but 1grn increments... because I'm at the very low end of velocity and pressure. In my .308 cartridges, loaded for my Savage bolt gun... which is capable of excellent accuracy, I range my weights by .3grn... and if I happen on a good node, I'll reduce that to .2grn on either side of the good charge to see if I can refine it.

 

[GeoDudeFlorida]

I have been reloading for awhile but far from experienced. Still have a lot of hours to put in and more calibers to reload before I can feel I am experienced. I use loading manuals and reloading data sheets from powder companies but I am perplexed about how I should approach increasing or decreasing loads by .1 or .2, etc. As an example, let's say a range of 47.1 to 50.4 is given for a starting load and max load. How would you go about load development and how would you determine if you needed to change a load by .2 or .3 or .6, etc? I typically work in trying different loads in whole grains and I select the load that performs the best based on reloading data. I've never tried to see if changing +or -0.5 g would make a difference. FYI - I don't compete or focus on precision rifle, so I am not chasing sub-moa. My hunting rifle is a Rem 721 and shoots factory loads sub-moa which is all I need for my purposes. Thanks in advance for sharing your experiences.

I have a 721 also in .30-06 and it’s more accurate than I can hold or see. I don’t use a scope, the factory irons are darn good, and I don’t have any special loads for it. It eats the same thing as my Remington 30S. I do have different loads for different ranges and critters though.
Loading ‘06 for a 721, my method is to start at the lowest low of a range of choices from a bunch of sources, then go down in half grain increments until I see signs the primer isn’t being reseated by the case setting back against the bolt face. Then I work up in half grains to the best 3-shot group from a cool, clean barrel. I’m a snap-shooter not a benchrester so I’m not after flea speck groups either, just minute of chest cavity is fine. First thing is to know your range, then the weather you will and won’t hunt in, and finally to know the size of your game. That’s how I learned it and still how I do it. I guess if I end up with a .3 or .8 it’s because it’s where I started as much as where I ended up. Hope this helps.

 

[sfl_gunner]

For me, it depends on where I am in the load development process. To start I do .5. After I find a window I cut it to .2 or .3 to find the absolute best on rifle loads.

For pistol my starting variance is .2 to .3.

 

[.38 Special]

As @Charlie98 notes, it does depend at least partly on the cartridge.

Having said that, I very rarely worry about a tenth of a grain, even in small, intense handgun cartridges. When testing a new load I will make a handful with the minimum charge and shoot them just to be sure nothing is horribly wrong anywhere. Then I will proceed - in big, relatively relaxed cartridges - to a medium load and then, if wanted, the maximum load. In a more intense cartridge, I will go from starting load to light medium, heavy medium, and then maximum.

Hunting and general purpose rifles get pretty much the same treatment. Working up loads for accuracy rifles is quite a bit more involved, of course...

 

[Roverguy]

For rifle, my starting point is whether there is a relevant load in Ken Waters’ Pet Loads If so, I start a grain or so below (depending on how close to max his pet load is - if at or close, I will start lower) and work up in .3 grs increments until I’m happy. I find I’m often happiest slightly below his ideal. For non Pet Loads, I start load development at the top of the bottom quartile of the published data range I am using and Round 1 is in 1 grs increments up to just shy of top of range data. Once that has narrowed things down, I will work around the preferred load from that round either side with 0.5 grs increments. With me, it’s pretty unlikely for anything but a competition target load to get further segmented in sub 0.5 grs increments. But that’s a little lazy.

 

[DMW1116]

I generally move in 1% increments. For 223 that means 0.3 grain increments. For 30-30 and 308 it’s bumped up to 0.4 grain increments. For handguns I use 0.2 grain increments. That’s the lowest increment I feel I can measure in my scale. That usually gives some options even in magnum loads in the teens of total powder charge (10-15 grains in 357 Magnum). I stay at least 0.2 grains below maximum in handgun cartridges. I generally stay at least half a grain below maximum in rifle cartridges. Usually more.

 

[Carl N. Brown]

My brief experience with reloading .25 ACP showed me that 1.6 grains was too hot, 1.2 grains was too cold, but 1.4 grains was just right.

 

[edwardware]

Think not of grains, but of percent. 0.1gr is 0.5% of a common .223Rem load, but 10% of some pusillanimous pistolero loads.

I don't compete or focus on precision rifle, so I am not chasing sub-moa.

But in general, in rifle loads. . . You just answered your question. Nearest grain is close enough.

 

[Chief TC]

Thanks everyone. I also have some large rifle magnum primers I want to use with WIN 748 for some of my 30-06 loads just because I have them but don't reload for anything requiring magnum primers. I read you can use them but start low and work up like always. Some of you talked about percentages here rather than grains. Would 10% reduction from max load be a starting point for magnum primers?

 

[N555]

Usually go half grain at a time then when I find a good load, I do 0.2 or 0.3gr increments for 1 grain around that "node" to really zero in on "the load".
Say I find 44gr shoots meh and 45gr shoots ok, but 44.5gr shoots really, really good, I'll load up some at 44.2, 44.4, 44.6 and 44.8gr.
I might break it down and go 0.1gr but I usually don't.

For full size cases like mauser, 308, shortened 308 such as 30t/c, 6.5 man bun, 30-30, ect 1/2gr at a time will get you close, for stuff like 223 probably want to do 0.2 or 0.3gr at a time. For big magnums like 30-06 and bigger one grain at a time.
For small handguns like 9mm, 45acp do 0.1 at a time, for magnums like 357, 44mag, 30carbine I would go 0.3 or 0.5 at a time.
5.7x28 absolutely 0.1gr at a time.
I don't load 40 or 357sig but since those operate on the edge of disaster I would work those 0.1 or 0.2gr at the time.

 

[Blue68f100]

Thanks everyone. I also have some large rifle magnum primers I want to use with WIN 748 for some of my 30-06 loads just because I have them but don't reload for anything requiring magnum primers. I read you can use them but start low and work up like always. Some of you talked about percentages here rather than grains. Would 10% reduction from max load be a starting point for magnum primers?

Large Mag Rifle primers are Not taller than a std rifle primer.

EDIT : My Error.: LR and LRM are the same size.

 

[mdi]

For me where 99% of my handloading is for handguns, the larger the caliber the larger the jumps/increases in charges sometimes .5 gr. With smaller calibers .2-.3 gr. seems to work fine. When my loads start "looking good" I will cut down charges to .2-.3 gr. for larger calibers (357 Mag, 44 Mag.) and .1gr for small (32 ACP 380 ACP, etc.). I use up to date reloading manuals and powder mfgs'. websites, never any "celebrity loads" or pet load websites' data...

 

[AJC1]

One percent steps in testing....

 

[.38 Special]

My brief experience with reloading .25 ACP showed me that 1.6 grains was too hot, 1.2 grains was too cold, but 1.4 grains was just right.

My brief experience reloading the .25 showed me that that was not the direction I wanted my life to take.

 

[Jim Watson]

My increment in pistol ammo is 0.2 or 0.3 gr. The powder measure won't hold closer than +/- 0.1 so there is not much point in trying every tenth of a grain.

 

[.38 Special]

Large Mag Rifle primers are taller than a std rifle primer, ~0.007". So unless you recut the primer pockets they may set proud.

Are you quite sure? I suspect you may be thinking of the difference between LR and LP primers. To the best of my knowledge, LRP dimensions are the same regardless of power.

 

[jmr40]

I have no idea about magnum primers being taller. But lots of people use them interchangeable. I've used standard large rifle primers in magnum rounds, and I've used magnum primers in non-magnum cartridges and so do a lot of others. Never heard of anyone having a problem with them being too tall. The only difference is that magnum primers MIGHT increase velocity by 20 fps. But I've never noted that.

I currently load for cartridges based on 30-06 or 308 brass. I've loaded for some magnum cartridges in the past and have always worked in .5 gr increments. I get the results I want.

Handgun rounds, or cartridges that use much less powder might benefit by using smaller increments.

 

[mdi]

Don't know why, but large rifle (standard or magnum) primers are .008" taller than large pistol primers (standard or magnum).

 

[Blue68f100]

Are you quite sure? I suspect you may be thinking of the difference between LR and LP primers. To the best of my knowledge, LRP dimensions are the same regardless of power.

Your correct. LRP and LRPM are the same size. Will correct my previous post.

 

[Chief TC]

Ahh, I found an older THR thread on magnum primer use. Thanks.

 

[Charlie98]

Would 10% reduction from max load be a starting point for magnum primers?

Depends on where your load is at. If you are near max data, I reduce 1grn and do a short workup. If you have a midrange load, I consider them interchangeable.

My increment in pistol ammo is 0.2 or 0.3 gr. The powder measure won't hold closer than +/- 0.1 so there is not much point in trying every tenth of a grain.

There is some truth to that. There is enough variation in both my powder drop, and my manual drops into my 5-0-5 scale to render a .1grn ladder test moot. I am not careless when I measure, but the level of my precision, coupled with variations in my equipment... it's a non-issue. There are cartridges I take a bit more care with... but I'm not going to skim 5 powder granules out of the pan to get the 5-0-5 pointer to move a tiny bit.

 

[.38 Special]

I am coming to think of measures which give consistent 0.0 throws in the same way as rifles which consistently hold half-MOA: everyone on the internet has them, but I hardly ever see them in real life.

It still seems to me that getting that kind of result takes either significant money or significant luck. I personally will continue to stick with "good enough" for most such applications.

 

[Varminterror]

A word of caution - most reloaders do not own a weighing or massing device capable of truly determining powder charge to 0.1grn, so incrementing charge weights in their ladder by 0.1 or even 0.2grn runs the risk of inadvertently misidentifying identical charges as different steps in the ladder. Many folks get lulled into believing their beam scale is exceptionally precise, but in reality, most models end up with only +/-0.1grn resolution. So loading to 0.1grn steps is a fool’s errand for the vast majority of reloaders.

Even when an reloader has equipment with sufficient resolution to load with extreme precision, powder charge development really isn’t so complicated, nor does it need to be so exacting. Any reloader saying they need to load to tighter resolution than 0.1grn, or really even tighter than 0.2-0.3grn isn’t a reloader from which anyone else should take advice. I CAN load to within +/-0.02grn with the equipment I have, but I sure don’t NEED to do so. I shared math here which proved out that loading to +/-0.1grn vs. +/-0.015grn (+/-1 kernel of powder) meant a margin of error in group size at 1000yrds which was smaller than 1 click in the scope turret even if loading charge weights in the absolute worst anti-node region of the barrel harmonics - and absolutely NO difference in group of charging in the node. And most guys aren’t shooting anything so critical that even that one click worth of extra error at 1000 would matter at all in their ammo - which was, again, as bad as it could possibly get, and a reloader would almost have to intentionally load that poorly.

 

[AJC1]

My ladders are .2 grains when one percent is less than .2. This is most pistol ammo for me. Don't have the capacity for a read out less than .1 so it's the smallest meaningful change I can make.