Charlie98
Member
Many folks get lulled into believing their beam scale is exceptionally precise, but in reality, most models end up with only +/-0.1grn resolution.
+1 Even my trusty RCBS 5-0-5 scale...
Many folks get lulled into believing their beam scale is exceptionally precise, but in reality, most models end up with only +/-0.1grn resolution.
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.+1 Even my trusty RCBS 5-0-5 scale...
If measuring +/- half a thousandth makes a person happy, I’m not going to rain on their parade
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?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.
If someone use 47.3 gr of something, why not just 47 or 47.5?
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.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.
Unique and Red Dot are very forgiving; TiteGrope and Nitro 100 are much less so.
I’m not looking for roving bands of Ninjitsu warriors hopped up on mescaline to engage with.
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.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?
Take 4% off the max , then take 10% off that
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?
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.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.