When using load data sheets made available through Hodgdon or Hornady I have noticed that their test rifles are light years better than mine. I am using an AR 16" barrel with a 1:7 twist. The most coherent way I can ask my question is, is there a place I can go, or a formula I can use, to find more accurate load data for my AR vs a 24" barrel with a 1:9-1:12 twist? Secondly, at what distance do you think "testing loads" would be reasonable.? I can shoot out to 200 yards, and my ultimate goal is to do that really well.
So many questions, so little resources.
- Thread starter BeerdedReloader
- Start date
You’re looking at it the wrong way. There is nothing wrong or inaccurate about 16” data used in your 24” gun. If they have your exact bullet, or bullet weight, that’s all you need. The only different between their gun and yours, is yours will have a higher muzzle velocity. It will NOT be making more peak pressure.
I have the shorter of the two barrels, I read a lot about 20"+ barrels while mine is only 16"
Op,
You sound like you are new to reloading. If so I would strongly suggest you purchase a good reloading manual and read it prior to starting out. Lyman, hornady, sierra and nosler are all good and any one would be good. This will help you understand the logic and physics of reloading.
There is good info on this site and others that can supplement the manuals.
You sound like you are new to reloading. If so I would strongly suggest you purchase a good reloading manual and read it prior to starting out. Lyman, hornady, sierra and nosler are all good and any one would be good. This will help you understand the logic and physics of reloading.
There is good info on this site and others that can supplement the manuals.
I did end up purchasing the Hornady 10th edition, as a newbie I practice a few things always. I trim cases to 1.75, I document my load top to bottom from trim to weight to powder to COL on my dry erase board to make sure that no matter what I always double check what I am doing. I hand scope every load, and I measure COL on every round after the bullet is seated.
Now that I am looking at load data and working on making rounds, I am finding it difficult to find solid information for my set up. Based on the powders that I have, the bullets, and the length and twist of my gun, it seems like some of the information is out there but not anywhere I have looked yet.
For the most part, Supersubes is correct . . . your velocities will tend to be lower due to the shorter barrel and so you even though they're using a longer barrel and a different twist, you should be able to find a good load between the min and max. However . . . there can be differences in pressure due to other factors (e.g. temperature, case volume, seating depth, etc). So, approach the suggested maximum load with caution.
I have been consistently reminded not to approach the maximum load at this early stage. I document it only to avoid it haha
You've probably already searched for what loads other people may be using in a similar gun as yours, so you might ask for what some are doing and give specific details about the cartridges you're loading (e.g. name of powder, case brand, bullet name and weight, COAL).
As far as your OP question about shooting distance, I'd recommend 100 yrds for now and then when you go to fine tune the load, shoot at 200 yds.
Lawd, that sounds like a lot of work!
Hats off to you for doing that, and I bet your ammo is super consistent!Out of curiosity, what powder/bullet combinations are you currently looking at? The reloading guides will still give you good pressure information, but for your gun's velocity data you will probably have to get a chronograph.
Max loads are max from whats happening inside the brass case in the chamber, not what happens inches or feet down the pipe when the barrel ends a bit earlier.
Barrel length only effects how long the pressure can push on the bullet, it doesnt effect the peak of pressure.
Note how the peak pressure is in the first 2 inches. The velocity is mostly made in the first 6 inches with 2k fps, it takes another 24" to gain another 800 fps.
Twist effects it but only marginally. Twist wont be the reason why you are over pressure.
If you have 200 yards to test on, test it there.
Test up in small even increments until you encounter pressure if you want to find your boundary. I like to know the point that I can go up to before I encounter my first pressure signs so that I can be sure I avoid it from that point forward.
Read this to see what to watch out for.
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Longer barrels often have less twist.
Normaly longer barrels shoot at higher velocity than shorter with the same load.
Without a chrono you can as a rough rule subtract 25 fps per inch of barrel.
Just tested some fgmm 168 in a 20 inch barrel. Mfg used a 24 inch barrel to get velocity figures our barrel produced 130fps slower due to the missing 4 inches 32fps per inch.
Each caliber and barrel will be different it's complicated so use a rule of thumb till you get a chrono.
Shoot at 100 and dial in the dope for 200+? . Hitting high or low will tell you how to adjust speed in your calculator till it lines up.
If that is what your fighting with.
Work up your loads slow as you reach top listed. I have only poped a few primers at max book loads and had a few flat looking ones. I believe shorter barrels were tested as being safe just want the faster data is what they prefer to advertise.
With some powders they actually mean MAX so tread lightly.
Normaly longer barrels shoot at higher velocity than shorter with the same load.
Without a chrono you can as a rough rule subtract 25 fps per inch of barrel.
Just tested some fgmm 168 in a 20 inch barrel. Mfg used a 24 inch barrel to get velocity figures our barrel produced 130fps slower due to the missing 4 inches 32fps per inch.
Each caliber and barrel will be different it's complicated so use a rule of thumb till you get a chrono.
Shoot at 100 and dial in the dope for 200+? . Hitting high or low will tell you how to adjust speed in your calculator till it lines up.
If that is what your fighting with.
Work up your loads slow as you reach top listed. I have only poped a few primers at max book loads and had a few flat looking ones. I believe shorter barrels were tested as being safe just want the faster data is what they prefer to advertise.
With some powders they actually mean MAX so tread lightly.
Load data is just to give you a window of charges to test. The data for your gun has to be located through that testing. My 16” AR may like a completely different load than yours. My 20” AR may like the same load as your 16”. Yes there are some loads that tend to shoot well in multiple guns. But if you do it right your load tests will confirm that rather than lead you there. Think of published load data as a safety guide, not a recipe book.
This is the most important thing. Your gun is the arbiter of truth. Not the other 10 of the same model on the rack in the store. That said to get down what works in your gun requires research and testing. Barrel length by its self doesn't affect accuracy within certain distances. As mentioned it can affect velocity and at longer ranges that may have disadvantages (like the bullet going trans-sonic) but if you're testing at 200 you'll never have that problem unless you're shooting a brick from your rifle at an already low velocity (think PCC.)
I would try at recommended COAL First and see what that does. Take the minimum in the load book, take the max in the load book, divide roughly into 10ths. After that, take those to a range for testing. Shoot at the same point and see how they cluster vertically. Horizontal is windage so ignore it for now. If you have a group at say 200 yards that stands out load towards the middle of it. That's a "node" where it resonates.
I would also advise a good log book for your loads; I'm (really) guilty of not having an adequate records system for my reloading work. It will help you keep from repeating testing needlessly.
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