Charlie98
Member
+1 Even my trusty RCBS 5-0-5 scale...
Tell Me About Using Fractions of a Grain In Load Development
- Thread starter Chief TC
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+1 Even my trusty RCBS 5-0-5 scale...
GeoDudeFlorida
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That’s why I’ve always considered 1/2gr about right and avoid absolute maximum or absolute minimum loads. Plus a 1/2 at the top end isn’t going to sheer the lugs and minus 1/2 at the bottom end isn’t going to stick a backed out primer in the bolt face or a bullet in the barrel - or worst case, convert deflagration into detonation.
If measuring +/- half a thousandth makes a person happy, I’m not going to rain on their parade but, I’m not climbing in the clown car either.
Charlie98
Member
Well, I finally figured out it boils down to managing expectations and risk.
At the 'Expectation' level, I've grown to understand the majority of my loads, and my shooting goals, don't depend on a few grains here or there. Even for my .308 Savage, the rifle I'm trying to squeeze the most accuracy out of at the moment, I don't have the expectation of absolute accuracy. I don't have the equipment, the shooting skills, nor the facility to expect BR accuracy out of any of it.
At the 'Risk' level, I've also grown to understand how to manage risk. Back Home, Years Ago, I worried about .1g difference in my charge drops... until I did the math. AJC mentioned percentages in his ladder workups, and the calculator is how I've grown to manage the risk. In a 43.5grn charge of IMR4895, in the .308, a difference of .5grn is only a 1.1% variance, a .1grn difference .3%... statistically irrelevant at my shooter level. Granted, that ratchets up when you are talking about pistol cartridges... .1grn in a 6.5grn charge of Unique in the .45ACP is 1.5%... but I've also found my powder choice (Unique) is not that sensitive to charge weight variations, unlike some other powders. I'm not suggesting carelessness, of course... dot the I's and cross the T's... but the days of losing sleep over .2grn difference in a lot of 300 .308's loaded for blasting are over.
I agree with you Charlie. For smokeless, I'm chasing the load that makes the rifle group the best overall for performance at various distances. I'm not competing nor trying to get the precision load for a variety of conditions. I try to keep my charge weights the same but a .1 or .2 gr variance works for me. Even though I am not necessarily pinpointing a fraction of a grain, I still wanted to know and learn how other folks determine this. If someone use 47.3 gr of something, why not just 47 or 47.5?
Charlie98
Member
Well... I'm not saying you can't see a difference loading 47.3grn vs 47 or 47.5grn, if you are looking for an accuracy node, that might be where it's at. I have seen differences in accuracy at .3grn (rifle.) My premise of the last post was that once your 'load' is established, and you start dropping charges, there may be .1 or .2grn variances within that set of handloads, and that most people probably can't detect at the target because it's within that 'window' of load tolerance for the rifle node. If you loaded 47grn, just outside of our fictional node of 47.3grn, and your throwing .2grn +/- around that 47grn... you may be completely outside your accuracy node... and that will show up at the target.
And, again, another aspect of that is expectation. My load of 43.5grn IMR4895 in my 150grn .308 blasting ammos isn't because that's an accuracy node, it's because it hit a velocity target I was looking for. That load is not an MOA load, but it works dandy at 100yds for MOBC (Minute of Body Cavity) accuracy.
GeoDudeFlorida
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I’ve been thinking strictly about .30-06 in rifle since that’s what the original post was about but I apply the same method to anything in or around that class of cartridges. Obviously the standard for .32Long is different and I put a lot more care into weighing those charges. Also obviously I choose powders with the widest possible tolerance for float in the small cartridges. Unique and Red Dot are very forgiving; TiteGrope and Nitro 100 are much less so.
But the basic understanding is, I’m not looking for any more or less than a mid-thorax hit at point shooting range with a handgun. I’m not looking for roving bands of Ninjitsu warriors hopped up on mescaline to engage with.
Charlie98
Member
I was thinking specifically of TiteGroup, too. That's the only powder I have used that is twitchy like that.
I think it's all that incense they burn at the Shaolin Temple... or maybe it's catnip... dunno.
You can get as precise as you like. If you're going for pure accuracy of gun/ammo combo, the sky is the limit. If you are a significant part of the equation, there's a really good chance that spending more time practicing/dry firing would be more beneficial. Kind of hard to have the best of both worlds without a significant investment in time AND money.
kalielkslayer
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The percentage method is the way to go. I load for .338 (75+grains) 7mmRM (63 grains) .243 (40+ grains) 22-250 (38 grains).
That said, I was taught 35 years ago to go up .3 grains. Just the way my mentor did it and it’s an habit I developed. When getting near max, I even drop to .2 grain increments.
Does .3 grains even make a difference? I believe so, significantly in some instances. My recent experience with H380 in 22-250 showed these results; 37.7 grains got me sub1”, 38.0 was one small hole, 38.3 opened up but was still barely under 1”.
I loaded 10 of each, shot 2 5 shot groups of all 3 loads to confirm. These results were the same as the original ladder but it became clear 37.7 was slightly better than 38.3 and 38.0 was still one hole except for 1 I threw.
200 yards, still 5 touching.
I’ll continue to do .3 grain increments although I realize I’m probably wasting time and components, and others may get as good results using a .5% increments.
That said, I was taught 35 years ago to go up .3 grains. Just the way my mentor did it and it’s an habit I developed. When getting near max, I even drop to .2 grain increments.
Does .3 grains even make a difference? I believe so, significantly in some instances. My recent experience with H380 in 22-250 showed these results; 37.7 grains got me sub1”, 38.0 was one small hole, 38.3 opened up but was still barely under 1”.
I loaded 10 of each, shot 2 5 shot groups of all 3 loads to confirm. These results were the same as the original ladder but it became clear 37.7 was slightly better than 38.3 and 38.0 was still one hole except for 1 I threw.
200 yards, still 5 touching.
I’ll continue to do .3 grain increments although I realize I’m probably wasting time and components, and others may get as good results using a .5% increments.
AJC1
Member
I think it's important to state that testing to determine the limit of a node is very different than loading an established load. I will change charge weight by .1 to map a node to the best of my ability. I will type in the center of the node I find on my chargemaster. I'm not seeking .02 grain resolution, but I will do my best to be as accurate as I can in testing so any slop at midnight before a match is allowed for the most it can be.
PonyKiller
Member
By no means an expert, but my process is simple for rifles, mine being mostly military.
Take 4% off the max , then take 10% off that then go up .5 grains Per off the min. If I hit a sweet spot I load a bunch.. 40 there if it's good I may be may not play .2 on either side. If it's good. Blast away and focus on technique
Take 4% off the max , then take 10% off that then go up .5 grains Per off the min. If I hit a sweet spot I load a bunch.. 40 there if it's good I may be may not play .2 on either side. If it's good. Blast away and focus on technique
Varminterror
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So you’re reducing max by 13.6%, because….?
If I read between the lines, you’re deciding that your personal comfortable max tolerance is 4% below published maximums, then you want your starting weight to be 13.6% below max - aka, 10% below 4% below max. Is that universal? That’s below DNR’s for some powders, and a couple hundred fps below potential for most rifle rounds, just seems like a long road to walk, and never finds the end?
JFrank
Member
I believe 3% increments is appropriate for charge testing, obviously one needs to do a little math and it’s important not to use to large of increment in small cases simply to not pass over nodes and the opposite is also true where we don’t want to burn up a magnum barrel testing too small of increment.
Pistols:
I do .1 on some pistol loads, especially with fast powders, but I understand that my scale may not be dead on, and I'm not worried about that. What I worry about is whether it shoots well, whether it's really 4.4 ,4.5, or 4.6 isn't important, it's whether or not the average of my drops from the measure shoot well. I record that setting on the measure, the powder, etc, etc. If it repeats good results, it's a good load.
That said, I don't like pistol loads that have to be dead on whatever .1 it is, I want one that shoots well over a spread. So for that example, if it shoots well, at 4.4, 4.5, & 4.6, etc, and I like the velocity/recoil level/accuracy, I set it for 4.5 on my scale, and load away.
Rifles:
.1 is so tiny in a 30, 40, 50, etc grain charge, that if it made a big enough difference to notice, something is wrong. .5 usually plenty until it's time to fine tune, then .2 or .3 is usually good enough, although for true match accuracy I'll fine tune a bit closer, but then we are really trying to find the center of an accuracy node, not the accurate spot its self.
I do .1 on some pistol loads, especially with fast powders, but I understand that my scale may not be dead on, and I'm not worried about that. What I worry about is whether it shoots well, whether it's really 4.4 ,4.5, or 4.6 isn't important, it's whether or not the average of my drops from the measure shoot well. I record that setting on the measure, the powder, etc, etc. If it repeats good results, it's a good load.
That said, I don't like pistol loads that have to be dead on whatever .1 it is, I want one that shoots well over a spread. So for that example, if it shoots well, at 4.4, 4.5, & 4.6, etc, and I like the velocity/recoil level/accuracy, I set it for 4.5 on my scale, and load away.
Rifles:
.1 is so tiny in a 30, 40, 50, etc grain charge, that if it made a big enough difference to notice, something is wrong. .5 usually plenty until it's time to fine tune, then .2 or .3 is usually good enough, although for true match accuracy I'll fine tune a bit closer, but then we are really trying to find the center of an accuracy node, not the accurate spot its self.
PonyKiller
Member
I should have mentioned, what I use that formula for is my 308 Spanish Mauser, I run exclusively mil brass through it. Was told by my local mentor to back off 4% off 308 data for mil brass, and 10 off that for starting load. It runs about a bit less than 100 fps off published 308 numbers over the chrono so far with a 21" barrel.
The rest of the steps are the same for all the other rifles save the 4% reduction.
AJC1
Member
Maybe reducing 10% for start and stopping at 4% below published max might follow the standard protocols better. If a book minimum is listed I would not go below that with rifle unless shooting cast with pistol powders. If your 100fps are for book listing 20" barrel tests, that could be easily explained by barrel ware.
