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Posted: 3/30/2016 3:22:00 PM EDT
The Essentials of an Accurate 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 add to 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 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/precision from an 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. In order to maintain that exact hold on the target throughout the trigger pull, it helps not to be fighting with 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.) Once you’ve put your accurate 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 to the same level as a precision bolt-gun, but today’s precision AR-15s are capable of a level of accuracy/precision 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 distance of 100 yards. I used Sierra 55 grain BlitzKings that were hand-loaded on a Dillon XL-650 progressive press. The group has an extreme spread of 0.474”. 
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I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... Quoted:
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Great little write up sir. Thank you for sharing this. I wish we could pin stuff like this. I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... Ooops ! That turned out much bigger then expected !! .... but, you know what I mean ! 
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I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... Quoted:
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Great little write up sir. Thank you for sharing this. I wish we could pin stuff like this. I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... Or just a Molon forum....................... cough cough site staff! |
| I just got started shooting groups to see how accurate my rifle and myself can be. Thank you Molon for all your ammo reviews as I do not handload. My rifle is an original MP Sport with the 5r 1/8 barrel free floated and a 2 stage RR trigger. It also has a Nikon p223 on top. I know it is not a match set up, but it is a good shooter. I have managed to get 1" 5 shot groups with factory AE 50gr varmint but it doubles to 2" for the 10 shot group. I think with more practice I may be able to get it to 1.5 with the 10 shot group. Hopefully I can pick up a match barrel One day in the future. |
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I just got started shooting groups to see how accurate my rifle and myself can be. Thank you Molon for all your ammo reviews as I do not handload. My rifle is an original MP Sport with the 5r 1/8 barrel free floated and a 2 stage RR trigger. It also has a Nikon p223 on top. I know it is not a match set up, but it is a good shooter. I have managed to get 1" 5 shot groups with factory AE 50gr varmint but it doubles to 2" for the 10 shot group. I think with more practice I may be able to get it to 1.5 with the 10 shot group. Hopefully I can pick up a match barrel One day in the future. That AE 50gr varmint ammo has been the best budget off the shelf load I have found for accuracy. Molon makes amazing write ups and I'm sure influenced many shooters to see what there AR15's will do. |
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Quoted: Ooops ! That turned out much bigger then expected !! .... but, you know what I mean ! https://image.freepik.com/free-icon/thumbs-up_318-31579.png Quoted: Quoted: I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. Ooops ! That turned out much bigger then expected !! .... but, you know what I mean ! https://image.freepik.com/free-icon/thumbs-up_318-31579.png Be glad dryflash3 doesn't mod here.  I'd vote to tack an updated "Collected posts by Molon". |
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Quoted: I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... Quoted: Quoted: Great little write up sir. Thank you for sharing this. I wish we could pin stuff like this. I think I'm going to put together an updated "Molon Reference Links 2016" thread to make things easier to find. ... That's a great idea. |
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Ever do any non 5.56 reviews? Hornady 6.8mm SPC 110 grain TAP versus 110 grain V-MAX 
The test vehicle for this evaluation was a custom upper built around a 16” Noveske Recon barrel chambered for the 6.8mm SPC cartridge. The barrel is stainless steel and has polygonal rifling with a 1:10” twist. 
As the title of this post states, this initial comparison is between Hornady’s 110 grain TAP load and the 110 grain V-MAX load. Upon visual inspection, the two loads appear to be identical. Both loads use the 0.277” 110 grain V-MAX bullet with a cannelure. Both loads have a crimp at the case neck (no case mouth sealant.) Both loads have a similar charge of a charcoal colored, short-cut extruded powder. The head-stamp of both loads reads, “Hornady 6.8mm REM SPC”. Both loads have a crimped primer (no primer sealant.) If you were to place a few rounds of each load on a table in front of me, I wouldn’t be able to tell the two loads apart. The 110 grain V-MAX bullet is pictured below along with other bullets of the same caliber produced by Hornady. 
The evaluation began with chronograph testing. Since I already had the chronograph set-up, I also chronographed two other 6.8mm SPC loads from Hornady; their 110 grain BTHP TAP load and the “Custom” 110 grain BTHP/WC load. (Other than the different box that they came in, these two loads also appeared identical to each other.) An Oehler 35-P chronograph with “proof screen” technology was used in testing. All strings of fire consisted of 10 shots each. All velocities listed are muzzle velocities, as calculated from instrumental velocities using Oehler’s Ballistic Explorer software. 
Accuracy testing was performed from a bench-rest at 100 yards using a Leupold Vari-X III set at 25 power for sighting. Wind conditions were monitored using a Wind Probe. All groups consisted of 10-shots each. Prior to testing the Hornady ammunition, I fired three 10-shot groups in a row using a control load that utilized hand-loaded 115 Sierra MatchKings. The extreme spreads for those groups measured: 0.99” 1.00” 1.12” for a 10-shot group grand average of 1.04”. Following my usual procedure for evaluating the accuracy of ammunition, I overlayed these three 10-shot groups on each other using the RSI Shooting Lab software program to form a 30-shot composite group. The mean radius for this 30-shot composite group was 0.37”. best 10-shot group of control load 
In order to give the Hornady ammunition every opportunity to prove itself, I fired five 10-shot groups of the Hornady ammunition from 100 yards and used the best three groups for evaluation. Starting with the Hornady 110 grain TAP load, the three 10-shot groups used for evaluation had extreme spreads of: 1.73” 2.08” 2.14” for a 10-shot group grand average of 1.98”. As above, these three groups were overlayed on each other to form a 30-shot composite group with a mean radius of 0.69”. smallest 10-shot group of 110 TAP 
The three 10-shot groups of the Hornady 110 grain V-MAX load obtained for evaluation had extreme spreads of: 2.43” 2.59” 2.74” for a 10-shot group grand average of 2.57”. The mean radius for the 30-shot composite group was 0.75” The composite groups are shown below side-by-side for comparison. smallest 10-shot group of 110 V-MAX 
30-shot composite groups 
Additional 6.8mm SPC chronograph data. 
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I wonder what affect, if any, a muzzle device has? I've read it doesn't, but just seems like the gasses exiting could influence the projectiles flight due to muzzle device venting.....even a slight influence at the muzzle would amplify 100yd down range....
Molon, have you ever done any testing with / without or of different MDs? ... Posted Via AR15.Com Mobile |
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Yep +1000 <a href="http://smg.photobucket.com/user/derek45/media/BURRIS1-4x/IMGP5815.jpg.html" target="_blank">http://img.photobucket.com/albums/v488/derek45/BURRIS1-4x/IMGP5815.jpg</a> <a href="http://smg.photobucket.com/user/derek45/media/AR/68_zpsrm0lnzov.jpg.html" target="_blank">http://img.photobucket.com/albums/v488/derek45/AR/68_zpsrm0lnzov.jpg</a> I prefer JP triggers and Love my Dillon 650 also 
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... 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. .......…. Yep +1000 <a href="http://smg.photobucket.com/user/derek45/media/BURRIS1-4x/IMGP5815.jpg.html" target="_blank">http://img.photobucket.com/albums/v488/derek45/BURRIS1-4x/IMGP5815.jpg</a> <a href="http://smg.photobucket.com/user/derek45/media/AR/68_zpsrm0lnzov.jpg.html" target="_blank">http://img.photobucket.com/albums/v488/derek45/AR/68_zpsrm0lnzov.jpg</a> I prefer JP triggers and Love my Dillon 650 also
JP handguards aren't to shabby either  . . .
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The most accurate gun I own is a 20 1/2'' AR. I have done everything possible to make it as accurate as an AR can become.
I have shot 1'' groups at 300 yards with it and it is hard to find any gun besides rail guns that are capable of accuracy like that. I have a custom 3 pound trigger that breaks beautifully, a 32x scope in a Larue mount and a stainless Wilson bull barrel on it. I started by lapping the upper and barrel extension. I use a RISII free float. I have the gas tube centered to the gas key perfectly, I spent a lot of care to align everything on the gun perfectly actually. I have the .223 chamber honed to a mirror finish. I have the barrel crowned perfectly and polished to a mirror finish. The bolt carriers inside is polished to reduce friction from the gas rings. The upper receivers inside anodizing is polished along with the bolt carrier. I use a mil spec. Emod stock that is enlarged inside to fit a commercial buffer tube super snug to create a fixed stock feel with better cheek weld. I obviously use a bipod [Harris]. These are the main aspects to accuracy as far as the AR15 rifle. The shooter and ammo are very important as well. |
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The most accurate gun I own is a 20 1/2'' AR. I have done everything possible to make it as accurate as an AR can become. I have shot 1'' groups at 300 yards with it and it is hard to find any gun besides rail guns that are capable of accuracy like that. I have a custom 3 pound trigger that breaks beautifully, a 32x scope in a Larue mount and a stainless Wilson bull barrel on it. I started by lapping the upper and barrel extension. I use a RISII free float. I have the gas tube centered to the gas key perfectly, I spent a lot of care to align everything on the gun perfectly actually. I have the .223 chamber honed to a mirror finish. I have the barrel crowned perfectly and polished to a mirror finish. The bolt carriers inside is polished to reduce friction from the gas rings. The upper receivers inside anodizing is polished along with the bolt carrier. I use a mil spec. Emod stock that is enlarged inside to fit a commercial buffer tube super snug to create a fixed stock feel with better cheek weld. I obviously use a bipod [Harris]. These are the main aspects to accuracy as far as the AR15 rifle. The shooter and ammo are very important as well. Shimming the barrel extension in the upper doesn't hurt either. |
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I have heard talk of using green Loctite to "bed" the barrel extension in the upper. Does anybody have any thoughts on this? Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. |
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Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. Quoted:
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I have heard talk of using green Loctite to "bed" the barrel extension in the upper. Does anybody have any thoughts on this? Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. Okay, you kind of lost me there. Where do you put the lubricant? Outside the chamber? |
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Quoted: Okay, you kind of lost me there. Where do you put the lubricant? Outside the chamber? Quoted: Quoted: Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. Okay, you kind of lost me there. Where do you put the lubricant? Outside the chamber? Pretty sure he meant between the barrel extension and the receiver. |
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Excellent! Please include some tips for tweaking an existing rifle. I just learned about the gas tube/key alignment and checked one rifle and found it to be off. I'll be spending the weekend aligning lots of gas tubes it seems. But the point about ammunition cannot be repeated often enough. This month at the range I saw a guy who bought a RRA national match upper and was shooting lacquer cased Tula ammo through it  |
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Quoted: Excellent! Please include some tips for tweaking an existing rifle. I just learned about the gas tube/key alignment and checked one rifle and found it to be off. I'll be spending the weekend aligning lots of gas tubes it seems. But the point about ammunition cannot be repeated often enough. This month at the range I saw a guy who bought a RRA national match upper and was shooting lacquer cased Tula ammo through it http://www.ar15.com/forums/t_3_118/692647_RRA_NM_A4_accuracy_test__Tula_and_handloads__iron_sights_.html |
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Yup, I got in on that thread. This off-site page HAD a wealth of data. The gas tube/key fit explanation is superb. Anyone know where to find the missing tutorial pictures? click
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But the point about ammunition cannot be repeated often enough. This month at the range I saw a guy who bought a RRA national match upper and was shooting lacquer cased Tula ammo through it
http://www.ar15.com/forums/t_3_118/692647_RRA_NM_A4_accuracy_test__Tula_and_handloads__iron_sights_.html
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Robert Whitley knows a thing or 2 about highly accurate ARs. Match winning ARs. Just sayin. 
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bump for existing rifle tweaks? I picked up one of these . . . 
I'm thinking of conducting a comparative test to see if there is any validity to the claims that some people have been making that when shooting from the bench, the size of their groups have been significantly reduced by using an adjustable gas block. ... |
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Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. Quoted:
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I have heard talk of using green Loctite to "bed" the barrel extension in the upper. Does anybody have any thoughts on this? Steel shim stock works better. It won't break apart under repeated loading/unloading. To determine if you can use it (or optimal locations for application) soak the chamber with a thin lubricant or weak solvent and apply pressure. If you need it, you'll see bubbles. That's an excellent test. Thanks for posting it. It seems that, if you can get bubbles, then there is movement between the barrel extension and the upper - which is a Bad Thing for accuracy. This is the very first concrete thing I've seen about "bedding" AR barrels that didn't have a bunch of "so and so does this and says it's important" or "all the real precision builders do this" attached to it. |
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I picked up one of these . . . https://app.box.com/shared/static/10ql0dlbess52542s07ncrunjksqbdar.jpg I'm thinking of conducting a comparative test to see if there is any validity to the claims that some people have been making that when shooting from the bench, the size of their groups have been significantly reduced by using an adjustable gas block. ... Quoted:
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bump for existing rifle tweaks? I picked up one of these . . . https://app.box.com/shared/static/10ql0dlbess52542s07ncrunjksqbdar.jpg I'm thinking of conducting a comparative test to see if there is any validity to the claims that some people have been making that when shooting from the bench, the size of their groups have been significantly reduced by using an adjustable gas block. ... A precision upper is on my list of things to build. I just haven't gotten to other things on the list that are somewhat more important to me. Bottom line: use quality parts, take your time and build the gun right, and it will be much more accurate than anything you throw together with crap parts, or anything you build with good parts but a "who cares" attitude to actually building it. |
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Can you provide a source for this shim material? Thanks, Rick I can't remember where I got mine. It's .002 thick and Stainless Steel. Lots of places have it, even Amazon. https://www.grainger.com/category/shim-stock/machining-supplies/machining/ecatalog/N-9oeZ1z0ng3c |
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I think there's a component of rifle movement that is directly related to how much extra gas is applied to the carrier. If you tune the gas block for a "just right" amount of gas for a particular load, there should be less movement (outside of recoil) of the whole rifle, which should make it easier to stay settled on the rests and thus reduce group sizes. That's their hypothesis, however, since the bolt/carrier group doesn't even start to move until after the bullet has left the barrel with a rifle-length gas system, I'm a little bit skeptical. We shall see.
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