I have a question as to why??

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74man

74man

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I have looked up load data for a .223 Rem and I don't understand why they always print that it has a 24" Barrel, 1:12 twist and the load data but most of us who have AR style rifles have a 16" barrels and either 1:7, 1:8 or a 1:9 twist rate so what data do you use? I have a Troy PAR with a 1:8 twist and a Kel-Tec SU16CA with a 1:7 twist so what data should I use or does it matter? I know the length of the barrel has an affect on the speed but does it affect any other parts of the data? The more I get into reloading the more confusing it becomes, I am lucky that I have a friend who has been loading for most of his adult life and he concentrates on long range accuracy so sometimes I ask him but it still gets confusing. Thanks,74man
 
► They are simply REPORTING what barrel they used in their testing.

► They are NOT telling you that the load data is only good for that length or twist rate.

► The purpose of the load testing is to measure CHAMBER PRESSURE.

► To gather this data, the rounds are fired in TEST BARRELS, not AR barrels.
 
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74man said:
I have looked up load data for a .223 Rem and I don't understand why they always print that it has a 24" Barrel, 1:12 twist and the load data but most of us who have AR style rifles have a 16" barrels and either 1:7, 1:8 or a 1:9 twist rate so what data do you use? I have a Troy PAR with a 1:8 twist and a Kel-Tec SU16CA with a 1:7 twist so what data should I use or does it matter? I know the length of the barrel has an affect on the speed but does it affect any other parts of the data? The more I get into reloading the more confusing it becomes, I am lucky that I have a friend who has been loading for most of his adult life and he concentrates on long range accuracy so sometimes I ask him but it still gets confusing. Thanks,74man
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Look for service rifle or 5.56 loads. They have always had data closer to what you want.
 
jmorris said:
Who is “they”?

I have books that are more than 30 years old now that have AR specific (fast twist) load data. That was back when you had to learn the hard way that bullets designed for slow twist barrels disintegrated out of 1:7’s due to centrifugal force.
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There’s also periodicals like Handloader that publish data for specific purposes.
 
Hornady 9th edition lists the data for .223, 223 Service Rifle and 5.56 NATO separately.

Regular .223 is with a 26" barrel and 1/12 twist.

.223 Service Rifle is with a 20" barrel and 1/9 twist.

5.56 NATO is with a 20" barrel and 1/7 twist. This is probably the data you're looking for.

Barrel length doesn't matter to a reloaded other than muzzle velocity. You need to measure that yourself to tweak your loads if it's that important to you.

https://rifleshooter.com/2015/12/22...el-length-and-velocity-26-inches-to-6-inches/
 
I load lots of 223 and 556 cases and I mostly consider bullet weight when looking at a given rifle to load for. I like 77gn in my 1:7 and 69gn in my 1:8 rifles and the little colored graphic the gentleman posted is quite handy.

Once you have the right bullet start low and see what kind of velocity you can work up
 
CoalTrain49 said:
Hornady 9th edition lists the data for .223, 223 Service Rifle and 5.56 NATO separately.
Click to expand...

Hornady 10th edition also lists this data separately.

As said above, read the front of the manual, until you understand it. Ask questions here or elsewhere as needed, and take your time figuring it all out. It really isn't rocket science, but you do need to be fairly precise.

Go slow, check and recheck, and enjoy it as a hobby that supplements your shooting hobby.

chris
 
In the middle nineties the move from 1:12 to 1:8 was well in progress. The 1:12 won't stabilize a bullet heavier than a 69 gr (I am sure there are some exceptions) and so with a 1:12, three hundred yards is about the limit. I tried shooting my 69 SMK's at 600 yards with a AR15, and I was hitting X after X until a little puff of wind blew the bullet into the 8 ring. The 69 was just floating in the wind at long range. When I was shooting service rifle the 77 SMK had just come in, I was using the 80 SMK at 600 yards, and the ballistics of the 80 grain bullet was about the same as a 168 SMK in 308. Not really impressive, but, workable.

I don't know if tighter the twist the higher the chamber pressure. That is a could be. But don't worry, data developed in 1:12 twist barrels will blow primers just as surely as data developed in 1:8 twist barrels. So here is what you do. When you start blowing primers, cut the load by half a grain. And continue cutting the load by a half a grain till the primers stay in. Your barrel will be different, loading manuals are just a guide.
 
Zahn said:
The twist rate will be a major factor in which bullet weight you select.

View attachment 1054783


Then once you select your bullet weight, you start working up your load for your rifle.
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It's worth noting that bullet weight isn't really the determining factor in required twist rates, it's bullet length.

Weight is only considered as a factor in twist rates because heavier bullets tend to be longer than lighter ones. If you removed the lead from a 55 grain M193 ball bullet and replaced it with Osmium, you'd have a bullet that weighs around 100 grains, but it'd still stabilize in a 1/12" twist.

The reason the military originally adopted the 1/7" twist was to reliably stabilize the very long (but relatively light), 63.7 grain M856 tracer round adopted by NATO.
 
It's all true that twist corelates to length.

However, the bullet makers sell bullets based on diameter and weight, with composition and shape also mentioned. How often do they list projectile length?

Further, that chart was one of many found in a quick search. While acknowledging the reality that the real factor is length, all the charts show weight.
 
Zahn said:
It's all true that twist corelates to length.

However, the bullet makers sell bullets based on diameter and weight, with composition and shape also mentioned. How often do they list projectile length?

Further, that chart was one of many found in a quick search. While acknowledging the reality that the real factor is length, all the charts show weight.
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Yup. Exactly but - you knew there had to be a but, right? - as I understand it and observed when I loaded for older service rifles, it’s not even projectile overall length, it’s the bearing surface/driving band length. The part that actually contacts the rifling. That was the toughest nut to crack when I was loading for 2-groove Enfield rifles.
 
74man said:
I have looked up load data for a .223 Rem and I don't understand why they always print that it has a 24" Barrel, 1:12 twist and the load data but most of us who have AR style rifles have a 16" barrels and either 1:7, 1:8 or a 1:9 twist rate so what data do you use? I have a Troy PAR with a 1:8 twist and a Kel-Tec SU16CA with a 1:7 twist so what data should I use or does it matter? I know the length of the barrel has an affect on the speed but does it affect any other parts of the data? The more I get into reloading the more confusing it becomes, I am lucky that I have a friend who has been loading for most of his adult life and he concentrates on long range accuracy so sometimes I ask him but it still gets confusing. Thanks,74man
Click to expand...

Manuals are giving you data to reload the cartridge, not the platform. Then they are giving you the data retrieved from their test platform. Testing a cartridge in every platform available would be expensive and not practical. Nor is it needed.
 
GeoDudeFlorida said:
The drama doesn't bother me. The accusatory tone bothers me. Like there's some conspiracy of barrel makers and loading data publishers to deceive the public.:eek: A simple reading of the testing process found in the beginning chapters of any load book answers the question.
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Been saying that for years. New loaders need to read the first chapters of several manual. The rest of the manual is just a recipe book

We used to read books and look up stuff in books!
 
There is definitely some fluff in the front sometimes, though. The Lyman 50th edition dedicates a section to the history of Lyman reloading manuals. I don't really need to read that in order to reload safely.
 
barnfrog said:
There is definitely some fluff in the front sometimes, though. The Lyman 50th edition dedicates a section to the history of Lyman reloading manuals. I don't really need to read that in order to reload safely.
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Well, if that's what your many decades of experience are telling you, that's fine but, personally I find that kind of history enlightening. I have also collected some of those old manuals, reprints and originals, and find them very useful in load development. But, that's just me.
 
GeoDudeFlorida said:
Well, if that's what your many decades of experience are telling you, that's fine but, personally I find that kind of history enlightening. I have also collected some of those old manuals, reprints and originals, and find them very useful in load development. But, that's just me.
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Enlightening in a historical context, yes. But the OP is being criticized for "taking short cuts" and thus being ignorant of information he would have known if he had read the manual completely. I just re-read the section on the history of Lyman manuals to make sure I wasn't talking out my bung hole, and I found nothing in there that would make someone a better or safer reloader.
 
barnfrog said:
Enlightening in a historical context, yes. But the OP is being criticized for "taking short cuts" and thus being ignorant of information he would have known if he had read the manual completely. I just re-read the section on the history of Lyman manuals to make sure I wasn't talking out my bung hole, and I found nothing in there that would make someone a better or safer reloader.
Click to expand...
Lyman’s used to test loading data using over the counter common firearms. The OP’s complaint is that the data he found was tested for a 24” pressure test barrel, not an over the counter common firearm. Is the light bulb still dark?
 
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