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[ARCHIVED THREAD] - The Essentials of a Precision AR-15 (Page 1 of 2)
Posted: 9/28/2010 8:10:23 AM EDT
The Essentials of a Precision AR-15
Without making this overly complicated, you need three basic components for a semi-automatic AR-15 to produce its best mechanical accuracy (technically, precision): a match-grade barrel, a quality free-float handguard and match-grade ammunition, preferably hand-loads tuned for your barrel. (The free-float handguard doesn’t improve the accuracy of the barrel per se, it simply prevents any outside influence from detracting from the accuracy of the barrel.) Anything after that will not immensely improve the mechanical accuracy of the semi-automatic AR-15, but several things can help you, the shooter, shoot to the level of the intrinsic accuracy of your semi-automatic precision AR-15. 
While there are certainly gifted individuals among us that can do amazing things with iron sights, most of us will benefit from using a quality, high-power scope to achieve the highest level of accuracy from a precision AR-15. In order to hit the exact same spot on the target every time, you have to be able to see that you are holding on the exact same spot every time. It’s also important for the scope to be mounted at the proper height and at the correct eye-relief for the particular scope. One of the most common errors I see with scopes mounted on AR-15s is the scope not being mounted far enough forward for its eye-relief. Also, in order to maintain that exact hold throughout the trigger pull, it helps not to be fighting a heavy, gritty, stock trigger. There are a variety of aftermarket triggers now on the market for both standard size trigger pins and the larger Colt trigger pins. Personal preference will definitely play a role in trigger selection. Among the two-stage triggers, I’ve found the Geissele triggers to be the smoothest, lightest, most consistent and most reliable. For single-stage triggers, it’s hard to beat the JP Enterprise Fire Control System. Keep in mind that the JP trigger does require fitting. Following the scope and trigger selection, some shooters will find that items like aftermarket grips and stocks will help them achieve a better “fit” with their AR-15. (Shooters don’t all come in the exact same size and shape, don't ya know!) Once you’ve put your precision rig together, you have to find a match-grade factory load that your barrel “likes” or better yet, develop a match-grade handload for it. A semi-automatic AR-15 is not going to shoot as accurately as a precision bolt-gun, but today’s precision AR-15s are capable of a level of accuracy that is truly outstanding for a semi-automatic rifle. The 10-shot group pictured below was fired from one of my Krieger barreled semi-automatic AR-15s from a bench-rest at a distance of 100 yards. The barrel has a 1:7.7” twist. I used Sierra 55 grain BlitzKings that were hand-loaded on a Dillon XL-650 progressive press. The load was developed using the Accuracy Node Detection Technique. The group has an extreme spread of 0.452”. 
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What is the Accuracy Node Detection Technique? I wonder if he's talking about the Ladder Method. http://www.longrangehunting.com/forums/f19/ladder-method-load-development-3173/ First post sums it up well IMO BountyHunter
Platinum Member Find Me on the Map Join Date: Jun 2007 Location: Fredericksburg VA Posts: 3,225 Ladder Method of Load Development –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Just built 300 WSM 1000 yard gun, had one day after break in to work loads before match. Tried something that worked well. Knew components H4350 powder and 190 JLK bullet, F210 primer to try. Only issue as load. Load range was 58-61 grains. Loaded cases (one each) in .3gr increments. Zeroed at 410 yards at bottom of large target with lowest charge. Shot and chrono'd one round at a time starting with lowest. Marked on paper at bench exact bullet location. About 3 shots into it, 4 bullets clustered, then 3-4 shots later 6 bullets (each different charge) went into 1 1/2inches. These clusters are supposed to be "sweet spots" for your barrel and load. Due to short time and not able to do further testing, just split the diff between top and bottom of top cluster. That gave me about 2900 FPS with load not near top on pressure but accurate. At match next day shot 3 sub 8" ten shot groups at 1000. Further testing will work on seating depth and fine tuning. But great way to find sweet spot to start with. 15 rds versus 15-5 shot groups. |
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Quoted: Quoted: Quoted: What is the Accuracy Node Detection Technique? I wonder if he's talking about the Ladder Method. http://www.longrangehunting.com/forums/f19/ladder-method-load-development-3173/ First post sums it up well IMO BountyHunter Platinum Member Find Me on the Map Join Date: Jun 2007 Location: Fredericksburg VA Posts: 3,225 Ladder Method of Load Development –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Just built 300 WSM 1000 yard gun, had one day after break in to work loads before match. Tried something that worked well. Knew components H4350 powder and 190 JLK bullet, F210 primer to try. Only issue as load. Load range was 58-61 grains. Loaded cases (one each) in .3gr increments. Zeroed at 410 yards at bottom of large target with lowest charge. Shot and chrono'd one round at a time starting with lowest. Marked on paper at bench exact bullet location. About 3 shots into it, 4 bullets clustered, then 3-4 shots later 6 bullets (each different charge) went into 1 1/2inches. These clusters are supposed to be "sweet spots" for your barrel and load. Due to short time and not able to do further testing, just split the diff between top and bottom of top cluster. That gave me about 2900 FPS with load not near top on pressure but accurate. At match next day shot 3 sub 8" ten shot groups at 1000. Further testing will work on seating depth and fine tuning. But great way to find sweet spot to start with. 15 rds versus 15-5 shot groups. I didn't know what it was called.  My grandfather was into benchrest and showed me this years ago, around 1975. I didn't think about this for years...thanks for the reminder. He helped me work up a load for a 220 Swift varmint rig and we did this. Molon, 
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What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. |
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What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Link? the google won't give up its secrets lol |
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Quoted: Quoted: What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon "interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Reminds me of an explaination from the BATF on gun regulations. |
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What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Link? the google won't give up its secrets lol Maybe I'll do a write-up on the technique and post it in the reloading section. |
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What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Link? the google won't give up its secrets lol Maybe I'll do a write-up on the technique and post it in the reloading section. Ok, cool A Molon-derived technique huh? 
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Molon, So this is different than the OCW technique then? As I stated above: The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. |
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What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Link? the google won't give up its secrets lol Maybe I'll do a write-up on the technique and post it in the reloading section. Ok, cool A Molon-derived technique huh? Affirmative. |
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Quoted: Quoted: Quoted: Quoted: Quoted: Quoted: What is the Accuracy Node Detection Technique? The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are. The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon "interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination. Link? the google won't give up its secrets lol Maybe I'll do a write-up on the technique and post it in the reloading section. Ok, cool A Molon-derived technique huh? Affirmative. Affirmative... You're too cool when you talk like that. So you came up with something yourself, you talk about it like it's an excepted method in use and proven. When asked for an explaination you talk circles in ten dollar words that say nothing about what the fuck you are doing. Maybe you will do a write up... Well good for you, maybe I'll read it. |
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Wow, tough crowd.
Until some of you contribute at a level approaching even half of what Molon has done, you should probably keep the snotty comments to yourselves. Do a search and you'll see he's not a keyboard commando. I look forward to hearing about the ANDT. |
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Krieger calculates that 7.7 twist is ideal for 77 grain 5.56. Not sure how they did the calculation. The 1:7.7" twist for a 77 grain MatchKing is based on the basic form of the Greenhill formula which is based on a specific gravity of 10.9 (which is not the correct specific gravity for the modern MatchKing bullet.) |
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Great info as always Molon. Why does Krieger use a 1:7.7 twist instead of 1:8 or 1:7? Can anyone answer my question...  Lot's of theories floating around, however, according to Krieger themselves, "we have settled on the 1-7.7 twist that guarantee's the 80's will be stable with no detrimental effect to 77's or 69's." |
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you need three basic components for a semi-automatic AR-15 to produce its best mechanical accuracy a match-grade barrel, a quality free-float handguard and match-grade ammunition, quote] I think you left one very important item out. The trigger. Without a good trigger, you can't hit the broad side of a barn. |
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you need three basic components for a semi-automatic AR-15 to produce its best mechanical accuracy a match-grade barrel, a quality free-float handguard and match-grade ammunition, I think you left one very important item out. The trigger. Without a good trigger, you can't hit the broad side of a barn. I see where you're coming from but a trigger doesn't make the rifle any more accurate, it just makes it easier for the shooter to perform closer to the accuracy potential of the rifle. That has more to do with the shooter's skill than the rifle itself. There are people that can outshoot me if they're using a GI trigger and I'm using a match trigger because they are better at trigger control. The barrel, handguard, and ammo are not affected by the shooter and are more at the root of accuracy itself. That said, a good trigger certainly helps me get to the inherent accuracy potential of the rifle I'm shooting much like a proper length stock, good optics, and a sandbag rest will help me. |
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What are your thoughts on headspace in regards to accuracy? Bench rest shooters using bolt guns load there ammo long so the tip of the bullet is touching the lands of the rifling. This is the best approach to minimize the bullet error as it jumps into the rifling. On an AR, you are limited because of the magazine. The ammo must be held to proper length in the magazine. Cartridges loaded longer than the magazine well will create jams or cause the gun to mis-feed in the magazine well. As far as triggers go, I have preformed many trigger jobs on pistols and rifles to get them to shoot more accurately. A mushy trigger which doesn't break clean is wasting time, if you are serious about shooting groups. Plinking into the back stop is one thing, but if your using match ammo that you purchased or took time to make, fix that trigger! Rifles are portable platforms.They are not fixed position weapons cemented in place. That's why triggers are also important. IMHO |
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Great info as always Molon. Why does Krieger use a 1:7.7 twist instead of 1:8 or 1:7? Can anyone answer my question... Lot's of theories floating around, however, according to Krieger themselves, "we have settled on the 1-7.7 twist that guarantee's the 80's will be stable with no detrimental effect to 77's or 69's." That was what I was told as well.... a little more stability for the Sierra 80s. |
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I use a similar method as described in a high power book by High Power and Service Rifle master shooter Randolph Constantine. There are subtle differences, and I like the method you describe a bit better. That said, anyone who hasn't read that book should. It's older, and most of his specific info is on the M14 type, but most everything can be transferred to the M16 family, and it's packed with tons of information. The thing weighs about 5 lbs I think.lol
Great info as always Molon. |
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Bench rest shooters using bolt guns load there ammo long so the tip of the bullet is touching the lands of the rifling. Incorrect. When "seating to the lands" the "tip of the bullet" touches nothing. When seating to the lands, the rifling of the barrel will engrave on the bullet at a point near the juncture of the ogive and the bearing surface, the precise point depending upon the particular bullet and chamber involved. The picture below shows the engraving on a Sierra 53 grain HP seated to the lands of a NATO chamber. 
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[ARCHIVED THREAD] - The Essentials of a Precision AR-15 (Page 1 of 2)
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