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Posted: 10/4/2006 12:28:54 PM EDT
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I've read Derrick Martin's Complete Guide to AR-15 Accuracy, Glen Zediker's The Competitive AR15; The Mouse That Roared, John Feamster's Black Magic: The Ultra Accurate AR-15 as well as a lot of more general information (manuals, online instructions, The AR-15 Complete Assembly Guide by Kuleck & McKee, etc.). I've built (assembled) a couple upper and lowers and have been satisfied with the results, but I haven't tried to build a dedicated tack driver yet. 1. I understand that the inherent accuracy of most high-end barrels will exceed the ability of all but the very best shooters, but I'd like to know what people think of the following two articles by Clint McKee: www.fulton-armory.com/Barrels.htm www.fulton-armory.com/Barrels2.htm 2. Other things equal, do matched uppers and lowers (e.g. those available from Les Baer or Rock River and others) enhance accuracy noticeably? Are they worth the premium over "generic" receivers like Stag/CMT or Mega? 3. Other things equal, do billet uppers or lowers (e.g. those available from JP Rifles, VLTOR, Larue and Sun Devil) enhance accuracy noticeably? Are they worth the premium over forged receivers? 4. How important is it to match the barrel and extension to the specific bolt you will use? 5. What are the lesser-known (e.g. not commonly found in books or online) tricks, tips and traps related to building an accurate AR? |
Yea Me Too! |
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1: reading the articles again, but it all seems to be a big voucher for Krieger bbls...; i'm not dissing krieger--they are some of the best out there 2: it probably would be best to have the upper/lower from the same manufacture, for best fit and finish, but imo, the lower/upper fit does not affect accuracy, just play 3: no; imo, no b/c lowers dont affect accuracy, just fit and finish of all the parts 4: for the best accuracy, it would be adv. to match em--new bolt w/ new bbl and break in together, etc 5: tips and tricks? barrel, dont skimp on the quality and craftsmanship on the bbl w/in your budget of course, with a good crown and proper twist for your loads; fit of bbl to upper and quality of the BGC/bolt; trigger, get a good trigger, probably a 2 stage match trigger; good, quality, consistant ammo, use ammo that runs in your setup--like any gun, some guns prefer certain ammo; sturdy stock, and some claim, a good FF tube i know this doesnt provide the best or most helpful info, but i hope it helps good luck |
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Thanks ALPHAGHOST. For those who don't bother to read the linked articles re Krieger, the gist of them is that single point cut rifling the barrel after profiling subjects the finished barrel to the least stress - particularly at the muzzle where it counts most. The author says Krieger is the barrel maker that profiles AR barrels before rifling them. This author argues that the best barrel is profiled and then single point cut (Krieger) and the second best is single point cut rifled and then profiled (Obermeyer, Rock Creek). Clint McKee/Fulton Armory uses Krieger barrels on their Peerless Grade rifles, but they could use any barrel they want to and offer other options. I don't see any obvious bias. I'm certainly no expert, though. |
| Upon the assumption that you have the best quality barrel then you must begin to think what other aspects of the weapon system contribute to accuracy. In specific the next most important aspect is how the chamber is reamed. This means both the dimensional issues and CONCENTRICITY , not to mention the exact choice of leade or throating. It varies as to which bullet you want to use most, as does the choice of twist rate. This is then followed by headspace, and that is where your bolt to barrel extension comes into play. The lugs should in theory bear evenly upon the mating surface on the extension... slap parts together... I don't think so. Best advice I can give is to think very deeply into how the parts should best be fitted so that they are square or parallel which ever, and proper alignment and tolerances held. Accuracy become easy with a well built weapon. |
I read this alot on here, but i don't understand why a good trigger would effect accuracy so much in a Black Rifle. can someone clarify this for me? |
+1...that about sums it up have you done much target shooting, just outta curiosity? a buddy of mine was a hardcore small bore shooter and i got into it a little... anyways, you can notice the difference when pulling a smooth 4 oz trigger on a custom Anchutz airgun or a 12oz trigger on an H&R custom .22lr vs. a 8 lb trigger pull on a Ruger 10/22--it all boils down to how much the muscles in your trigger finger and hand and the force needed to press the trigger home and connect the shot to your target a lighter, smoother trigger makes it easier to connect w/ the least amount of movement and vibrations to make the shot while co-insiding w/ your breathing and muscle movement (or lack thereove) h/w, make sure its not too light for safety and training reasons (i.e.: i would not recommend a less than 2lb trigger on an AR or other high powered rifle) as a competition shooter, diet, form, muscle control, breathing, sight picture, eye blinking, arm and body position, and trigger finger all play crutial roles to connect w/ the rifle to drive bullet after bullet as tightly as possible well, trigger pull, weight, and reset all provide a critical role, mechanically, to blend w/ the shooter; dry firing and range time help tremendeously for the shooter to adapt to how and when the rifle's trigger "breaks" so you take that shot at the opertune time--during that 5-8 sec when your hold your breath and your sights are on the target....in general, the LEAST amount of movement your body does (when it comes to fine muscle control, such as on the trigger), the more stable the rifle, and hopefully the better your shots you would be surprised, but you can have THE most accurate rifle out there, but imo, 85% of the accuracy lies w/ the shooter (form, how comfortable the equipment is for you, etc); the rest falls on ammo and equipement |
Thanks - good info. |
I've been told (by a fairly credible source) that proper gas tube/gas key mating is critical to top notch accuracy. The gas tube can't impinge on the gas key anywhere or accuracy will suffer... |
| Without getting into a lot of details, a good trigger is an absolute must. On my precision bolt rifles I use 2 pounders that break like a glass rod. You should actually be "surprised" when the trigger releases the sear. First 2 things a stock AR need to improve accuracy is an accu-wedge and a good trigger-From there, well, the sky is the limit |
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i was reading parts of feamsters book again last week. the part that jumped out at me was the upper/lower fit experiment. it does make a difference. he talked about shims and bedding, nut im not going that route. so next time i buy receivers, it will be a set drilled for pins at the same time. randall at ar15 barrels fits bolts to the extension. dont remember the details, just remember him explaining it before. i cant justify the $ for a krieger. they may last longer, but not twice as long. they cost twice as much as wilsons. i also use an anticant device, cuff slings, and adj gas systems. the meplate unformers will help if the rounds are single loaded. pushing them up the feed ramps smashes them up. |
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'any ammo' is a subjective term. No point taking a high end accuracy build and feeding it shiite. Even at that, the folks feed theirs ONLY handloads with 80gr bullets won't let you take a 55gr 5.56 near theirs. It may sound silly, but on a high enough budget, a more adjustable stock may turn out to be the most helpful. If you're using an optic w/ needle gun, sometimes something as simple as a highly adjustable stock makes all the difference. |
very good points. i just took the adj stock off the other night, ill probably be pissed when i go to the range next. |
I am fitting for endspace (bolt to extension) as well as headspace. The "Spec" for endspace allows for about 0.010" between the barrel, bolt and extension. This would allow the bolt to bear on the case when rotating into a locked state. This also allows the bolt to be SIZING the case as it locks up. With variation in brass hardness, you can then get INCONSISTENT SIZING, making for differences in headspace and primer igniton. By reducing endspace down to about 0.002" to 0.004", the bolt will now come to bear on the back of the barrel as it locks in. This changes the consistency of lockup. The bolt now locks up and same with or without a cartridge in the chamber. I also feel that this helps with the "first round flyers" that autos are known for. As for Krieger vs. Wilson, you are talking apples and oranges. The Krieger is a cut-rifled blank. It will be VERY consistent in bore straightness, bore diameter, groove diameter, twist rate and have a perfect finish lay consistent with the direction of bullet travel so it will not copper foul. The Wilson blanks are button rifled standard grade blanks. You are NOT paying double the price to get double the life. You are paying for the consistency and quality of the Krieger. The Krieger will tend to be more accurate with a wider RANGE of ammo than the Wilson. The Krieger will certainly foul less and clean-up easier. With the best load developed for each barrel, the Wilson can certainly shoot good, but it's no match for a Krieger. If you are not a handloader developing loads for the barrel and using a relatively high power scope(8x+) to shoot your groups, you would not be able to fully realize the accuracy potential of the Krieger and the Wilson will probably suit you fine. |
thanks for posting the bolt fitting info again. i wonder if thats where my first round flyers come from, i just figured it was cold barrel shots. someday i will get a krieger. i can shoot my 1/10 wilson standard grade 24" .308 1/2-3/4moa regularily with match handloads. but i am having issues with my 1/9 16" .223. cant get submoa, im gonna run some jb through it today. i think as your shooting skills go up, so should your taste in barrels. |
Differnet topic. That said but mine have worked with everything I have tried since I ditched the fancy CS action springs. Also see Tehl.lama42's response above. For a non-life critical tack-driver, it doesn't matter. I can tune the rifle for the ammo that works best in it using an adjustable gas system, carrier/buffer weight, etc. Thanks all for the great responses 
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inherent accuracy will depend on some basic and crucial things. the trigger isn't a place to skimp. forged, whatever isn't as big as what you may think. to sum it up for you: barrel quality, barrel quality, barrel quality. a quality barrel with a proper crown will make the majority of your performance. two cents. |
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