I’m never going to get any more work done today, since I found this thread on my lunch break.
-
Having trouble using the site?
Contact support
Whats Going on here
- Thread starter MAGA4LIFE
- Start date
I’m never going to get any more work done today, since I found this thread on my lunch break.
What question? I've been beat down with smart ass comments, ask a serious question and I'll be most happy to answer it.
Ok look,,,,I realize cheap is cheap, got it, but honestly? If scope rings hold the scope I'm place and do not allow any movement at ALL, then are they NOT good rings? I mean the purpose is to hold the scope I'm place, which these are doing, so please, elaborate.
Rings can impart a torque to the tube and mess up the internals if they are not precision lapped and aligned to the scope. Vortex might repair the scope for free.
Since you can shoot fairly well the problem is
a) scope killed by rings
b) the rings themselves
c) can slip with recoil but seem tight
d) anyone of many gun parts for a defect
e) assembly fit and torque, like barrel nut, gas key, bolt and carrier, burr inside barrel @ gas port
f) some unknown gremlin
g) what is your zodiac sign?
Since you can shoot fairly well the problem is
a) scope killed by rings
b) the rings themselves
c) can slip with recoil but seem tight
d) anyone of many gun parts for a defect
e) assembly fit and torque, like barrel nut, gas key, bolt and carrier, burr inside barrel @ gas port
f) some unknown gremlin
g) what is your zodiac sign?
Last edited:
You said you put your scope on the rifle and got consistent results. So change out the scope/mount whatever you did to get the consistency and go from there.
just FYI a Walmart centerpoint etc will yield the same results. He needs more reliable optics if that is the culprit
Was said already but keep the rings on the upper together and don’t have one on the upper and one on the upper part of the handgaurd etc
just FYI a Walmart centerpoint etc will yield the same results. He needs more reliable optics if that is the culprit
Was said already but keep the rings on the upper together and don’t have one on the upper and one on the upper part of the handgaurd etc
I don't think he's a troll, just doesn't have people skills.
Will be a great SH member some day.
Fit right in
Without the extensive knowledge of how an AR functions, be careful about helping buddies.
What size magazine did you guys use?
Hope it wasn't one of those 30 rounders.
Will be a great SH member some day.
Fit right in
Without the extensive knowledge of how an AR functions, be careful about helping buddies.
What size magazine did you guys use?
Hope it wasn't one of those 30 rounders.
The scope could be broken, or the mounts. Which mounts did you use when you put your scope on his rifle? That should tell you everything.
Sometimes scopes are busted, right out of the box. I thought you said the scope was brand new.
And hey, all anyone is trying to do here is help you and have some fun. Calling people fucking assholes will only get you so far.
Last edited:
So, the rifle was inconsistent with his scope, but WAS consistent with the scope from your rifle? If this is the case then the problem is either the scope, the rings, or the way they interface with the rifle. How were the rings mounted to the rifle? Were both mounted to the upper receiver? Was one mounted on the handguard? What torque was used to mount the rings to the rifle? What torque was used to mount the scope in the rings? How does the scope from his rifle shoot on your gun?
Tik, Tik, Tik. I am waiting. Please read post #26 and answer the question, I am on pins and needles. In case you do not know posts are numbered in the upper right corner of the post.
I have helped a lot of guys like your friend.
I've seen those "two good shots fine" groups before.
Your answer has been given.
You are busy waving your dick around.
Listen carefully.
SOMETHING
IS
LOOSE
It might be that hillbilly lower you put together.
It could even be the reticle in the scope.
Something is loose.
I've seen those "two good shots fine" groups before.
Your answer has been given.
You are busy waving your dick around.
Listen carefully.
SOMETHING
IS
LOOSE
It might be that hillbilly lower you put together.
It could even be the reticle in the scope.
Something is loose.
OK, so you make a typo and we all
jump on it.
8" plate @ 300 yds is Bear Creek.
Your goal should be to get a little better.
(and avoid damage/injury).
There are many here that shoot 0.1 MOA (not me).
A gazillion that shoot 1 MOA or less.
Some of us are proud to get on paper.
View attachment 7251771
Some proud of that fluke one shot miracle
Like my avatar
Dialed from a 100 yard zero to a calculated 600yd zero and popped a clean cold bore X.
No brag, just fact
Perhaps, but I don't take too kindly to being condicended to. I'm just trying to help my friend figure out why his first AR build is so inaccurate.
I took MY scope off MY Ruger, qd mount. I placed it on his Rifle, and although it was off, it was hitting in the same spot every time. I did NOT place his scope on MY Rifle, although I prolly should have in retrospect.
I think you have it figured out. New decent optics and mount. I’ve had great luck with the Sig Romeo 5 red dots. Can be had for $90-$150 used or new depending where you find them. Would serve him well. Or just a Burris PEPR Mount and a decent scope would do fine.
Vortex will take care of him if it is the scope. I had 3 vortex and had 2 replaced because they failed.
Either way it’s most likely the optic. But checking the rifle over in general wouldn’t hurt
Double check the screws, one or some might be stripped... and while the scope may feel snug, if a screw is stripped, the recoil of the rifle may be throwing shots.
Easy to check.
News flash, yes you do have to pay for quality.
I'm going to guess you're one of those people that will see two products spec'd similarly and look kinda similar but one costs $300 and the other costs $1000 and think you're getting the same product and probably say something along the lines of "you're paying for the name" and have not a clue that the more expensive one is made better and with better materials. You don't get the same quality in a $200 upper or optic as you do in a $1000 upper or optic. That's how we all wish it worked, but it doesn't.
Here’s how a quality upper shoots. Rounds 6-10 through a new Proof Research 18” SS 223 Wylde tube with IMI Razorcore 77gr into a .338” CTC 5 shot group.
Last edited:
The problem is the bump stock dude. Take that off and you’ll group better
I am starting to think it's real. The laws of Natural Selection are eyeing him up though
There you go!
It's a vortex Crossfire. It'll need to go back at least once. It's broken and moving randomly.
And if you're going to keep being a dipshit expect to stop receiving any sort of help.
One note to think about, I bought a Bear Creek 6.5 Grendel and it was like 6 or 7 inch groups. It did not shoot well till after about 50 rounds. My son in law went through 3 Bear Creek barrels and never got one to shoot under 2" at 100 finally got a Ballistic Advantage barrel to replace Bear Creek to get 1/2" groups. Im giving mine another try when I get better weather then. ???
Something no one else has asked is where in the range of adjustment you are.
Scopes can have erratic shot groups if the internals are jacked clear over to one side or another.
I'd optically center the scope and shoot it without making any adjustments to see if it groups, even way off.
I'd also make sure that you aren't mounting your front ring on the handguard. Scope needs to be on the upper only.
Scopes can have erratic shot groups if the internals are jacked clear over to one side or another.
I'd optically center the scope and shoot it without making any adjustments to see if it groups, even way off.
I'd also make sure that you aren't mounting your front ring on the handguard. Scope needs to be on the upper only.
I understand that not everyone has $1000s to spend, but due diligence would point you in the right direction....I built an upper with a Faxon pencil weight barrel, and am getting an inch @100...which I'm happy with......just built ar10 in 6.5 creedmoor with a Bartlien barrel that ran $600 + and it shoots lights out. But quality does equate with performance in the gun world. But I'm with everyone else, as soon as the optic change "fixed" the grouping, problem solved......don't understand why that didn't answer his question right there.....but, everything is a learning experience.....
I will add this about Bear Creek Arsenal barrels..I have several and have not had even one bad one.And several months back Kotaboy32 on YouTube built 2 AR15's..One very expensive from a Ballistic Advantage Barrel to Aero Upper/Lower to expensive scope..Everything High Dollar....He Called it The Full Monty..The 2nd one was built Cheap..PSA Upper/Lower,Bear Creek Barrel...Everything on it Inexpensive..He called Economy One...In the End the Bear Creek Barrel that cost about $70.00 outshot that $750.00 one.. Inexpensive Does not always equal Cheap and no good.
I have read many of the responses.
If nothing can be found, do check the barrel crown.
If it is not uniform, say a nick or chip in it, it will definately affect accuracy.
I assume you are shooting from a rest.
Change optic, change ammo AND when you mounted the scope rings did you align them (or a one piece mount) did you push them forward against the rail?
Is that a 3 shot group you poser? Shoulda pulled out the Kidder and showed us a real ten shotter.
I know you can do better than that.
Yeah I got it. Thanks brother. If you need anything in that line gimme a call. I'm doing a lot of clearing out the gunroom.
OP, are you one true badass motherfucker who can bench 275 by chance?
Wow, this and my coffee has started my day off with a smile.
My problems seem so irrelevant now.
My problems seem so irrelevant now.
I stop my groups after one shot. I get into the .1s if I do my part.The old "it can only get worse from here" theory -I subscribe to that one too
That's an excellent suggestion, and as a matter of fact, he had indeed mounted one mount to the hand guard, and the rear to the receiver. I re mounted it correctly and an already seeing vast improvement. We're going to shoot it again today after work and I'll try to dial it in tighter.
I'm trying to discover the elements of building a sub-moa AR in 5.56 NATO - This exercise is to learn facts.
First I scoured the PRS blog, and YouTube then poked around here and there for nuggets of truth.
Here's what I think I know at this point.
1. The BARREL is the most important item. It must be a high quality barrel. The chamber must be installed by indicating on center, then reaming with a piloted reamer. Experience counts. I purchased a discontinued Proof Research button rifled 16" barrel after calling Proof to confirm that they stand behind its accuracy.
1A. The barrel must be seated to the upper correctly. This requires most uppers to be squared using lapping compound and an inexpensive tool (if you own a lathe, make your own, if not look at Wheeler for a kit).
1B. The barrel must not move between shots. Restated, the barrel must 'point' to the EXACT same place every shot.
1C. You can use Locktite 620 (green) to glue the barrel extension into the upper. If you do, you will have to use a torch to heat the upper to more than 500F to remove it, and you will probably have to burn the Locktite off the barrel extension to clean it up if you plan to reuse the barrel. I know this because my first barrel was a STAG 24" Varmint barrel that simply would not shoot under 1.5 MOA. If you Locktite the barrel it WILL NOT MOVE regardless the barrel nut torque applied.
1D. If you do not use a glue, then use a copper infused anti-seize (NAPA). On my second barrel (the Proof Research) I changed gas system and handguard, which changed the barrel nut to a hex nut (I LIKE the hex nut, I don't like the cost of a 1-1/16" crows foot to fit the torque wrench!). Using the SEEKINS barrel nut, I first tired 50 lb-ft torque. Got 1.5 MOA. Then 65 lb-ft the barrel nut moved about 3 degrees as I brought it up (always increased torque, never backed nut off), the nut moving did not affect the gas tube alighnment, but in a conventional barrel nut (with gas tube holes) it would have been a poblem. At 65 lb-ft 1.5 MOA continues. Eventually bumped it up to 75 lf-ft and expect to leave it there. It does not appear that torque changes (above 50 lb-ft) have any affect on accuracy with my barrels (I did something similar to the STAG 24" Varmint barrel, it turns out that barrel had it's chamber installed (wait for it … ) 1-2 MOA out of true. I know because I cast the chamber and measured.
2. The TRIGGER is the second most important piece of hardware. "Everyone" says so. I started shooting competitively at age 7 and was a contender for the US Olympic Team the year I won the Southeast Asia lottery. I've got an 'educated' trigger finger, and I can shoot any military trigger at expert level. I didn't want to believe a 'better' trigger would make $200 worth of difference. Recently I bought a TRIGGER TECH AR15 ADAPTABLE trigger. It's a two stage with the first stage takeup about the same as the center blade on a Savage AccuTrigger. I adjusted the trigger to nearly it's lowest weight (2.5 lbs). This trigger really does feel like a quality 1911 trigger when it breaks. I can't prove I shoot any better with it, but I think I have a slight improvement in eye-hand (trigger finger) coordination that may be worth 0.25MOA in 'pointing where I want it to go off'. The hammer is a bit faster so lock time is probably a bit quicker (always a good thing), and I believe that (faster lock time) is the big improvement for me. Anyway the trigger feels so good that I think its worth the cost, even if it doesn't show up as any better groups for me. For someone without the 'couple million' trigger pulls's I've done, this trigger may very well create a measurable improvement in accuracy.
3. SIGHTS. In International Smallbore and Service Rifle competition we used iron sights to make 0.5 MOA corrections that were measurable and repeatable. The days when my eyes could do that are long gone. Now I use a scope exclusively. I used to have a lot of different and very expensive scopes on my rifles. Then Vortex came out with the DIAMONDBACK TACTICAL 5-25x50 FFP and priced it well below its performance point. I traded in all my NightForce, Burris, and other scopes to replace every one of my scopes with the same model. Now I only have to learn one reticle, one set of adjustments, one … well you get the idea. So when this rifle (wearing that scope) would not shoot well (back when it was the STAG barrel), I used my 308 and 204 to 'qualify' their Vortex Diamondback scopes with TALL TARGET and BOX tests so I knew the scopes were working correctly, predictably, and by how much to correct for 'click' error. Then I took the scope off my 204 (it's a consistent 0.3 MOA rifle) and swapped with the AR scope. No change, still getting 1.5 MOA on the AR. The AR's scope is now on the 204 and is consistently printing sub-half MOA. The mounts on the bolt guns are massive tactical style attachments, while the AR has a Vortex 'cantilever' scope mount. The jury is out about this mount, but I know I need to keep the scope forward and high and attached on the upper (never the forened) to ensure it doesn't move between shots. I had some 'issues' with the Vortex mount to start with that I solved by boring out the holes for the screws that apply gripping pressure to the PIC rail. I also used some of that Copper infused anti-seize grease to ensure the clamp would move into its tight position without restriction or excess friction, and of course I torqued it to spec. I'm 'pretty sure' this mount isn't the problem.
4. GAS SYSTEM. The gas tube must not be under any tension when the bolt is closed. If it is, then when the bolt moves, the barrel will move, and not in a uniform way. You can check this easily when building by watching the gas tube while closing the bolt, you can also smoke check the gas tube to gas-key fit to ensure there is no lateral pressure. In my latest configuration I am using an adjustable gas block that has set screw that coordinates with a dimple in the barrel to set the gas block location correctly. if you use a clamp style gas block, keep in mind that the block should not touch any shoulder on the barrel. The AR15-A1 hand guard had a 0.015" thick steel plate that was captured between the gas block and that shoulder. Your gas block should install with a 0.015" gap if there is a shoulder.
4A. While we are on the subject of the gas system, using an adjustable gas block should improve your accuracy by reducing the stresses transmitted though the system. Lower gas pressure in the gas tube, gas key should allow the bullet to exit the barrel well before the bolt carrier group begins to move.
4B. An instructive test of your gas system works like this: (Be sure your rife is unloaded! Have a safe landing zone for your BCG!)
1. With the upper removed from the lower.
2. Remove the Charging Handle and the BCG.
3. Reinstall the BCG without the Charging Handle.
3 . With the bolt carrier group fully forward, and the bolt in full lockup.
4. Apply compressed air to the barrel at the muzzle.
You will likely be very surprised at how little air pressure it takes to unlock the bolt, and toss it out the back of the upper. If you wanted to get the system wet, you probably could easily do this with your lungs!
Anyway, you can use the changes in the sound of the air as you manipulate the BCG to get some idea what the relationship of the gas tube to gas key is. Keep in mind that gas ports through the gas key to the right side of the BCG.
5. LOWER. There is very little other than the trigger about the lower that affects accuracy directly. As long as the lower fits well enough to fire the rifle it should be capable of good accuracy. That's what my brain says. When I hear the upper/lower rattle, when I feel the upper/lower move around, I just don't feel accurate. There is a very good and simple fix. WHEELDIAMOND (.com) produces a little horseshoe shaped piece of Aluminum that you can fit to your upper that will (if correctly installed) totally eliminate all movement between the upper and lower. I absolutely love mine. I guess things that make you feel better might make you shoot better, it's not going to make the rifle shoot any better though.
6. AMMO. In order of importance this is probably really number one or two. Barrel manufacturers will guarantee accuracy only with match quality factory ammo, because if the ammo is inconsistent, the accuracy is inconsistent. However consistent ammo alone can not make a rifle accurate. My Proof Research barrel has a 1:8 twist. It should be good for 55-75 maybe 80 grain or heavier bullets. So far hand loads and factory match ammo from Black Hills and Hornady are still not consistently sub-MOA regardless the bullet weight. Some are atrocious! For example XM855 will not shoot consistently below 2 MOA (which used to be ok for National Match, but I'm looking to hit ground squirrels at 300+). Black Hills consistently shows ejector swipes on the case head (over pressure), and has not shot well in any of my barrels, HORNADY MATCH is not shooting sub-moa, and my handloads, mostly using CFE223 have not been impressive except for velocity. I use QuickLoad, a lot of loading manuals, and direct measurement to understand a load. I've found setting up QL for 5.56 NATO and using the actual case volume of water has allowed me to work in a much higher velocity range than most manuals recommend. My PRESSURE TRACE confirms the QL predictions for pressure, and my LAB RADAR is right in line with QL velocity predictions. Thing is, I am not having a good time getting ES (extreme velocity spread) down to below 50 fps. Typically in 10 shots of a given load the ES wiil be 100-200 fps. I've tried sorting for case volume, more powder, less powder, crimp, no-crimp and neck tension adjustments with nothing pointing to a 'better way'. I've loaded one-at-a-time in a single stage press, and 'production-mode' on my Dillon XL650. I seem to be able to get Dillon loads that work as well as any I can load single-stage. Neck turning didn't improve group size either, but it did improve concentricity. I've measured runout on loaded ammo, then cycled it through the rifle from the magazine by dropping the bolt from bolt-lock. My adjustable gas block is set to 'just work' plus 'a little' which shoots soft and reliably. One would think the difference between bolt-lock and shot-to-shot loading would be minimal. Anyway the runout of 'cycled' ammo is the same as it was before loading it into the rifle. I've marked up bullet noses to check for contact, and only see very light scratches, and left or right feed appear the same (but on opposite sides of the bullet). At present, I'm chasing a 5 shot 0.4MOA group that probably was a statistical anomaly. It was a Hornady 40g VMAX load. I think the 40g VMAX may shoot very well in this rifle, and the latest round of testing though mostly 1.0-1.5 MOA the groups were more round and group size vs charge was more consistent than previously. My memory is 'itching' telling me there is a chance that flyers are coming from the 3rd and 5th shots more often than not. Don't know what that means yet, if anything.
CONCLUSIONS:
The sub-MOA AR15 may not be a 5.56 NATO (or Wylde) rifle. All of my very accurate guns have the ability to load the bullet to zero jump, and find their highest accuracy at a point less than 0.050" of jump. My AR15 barrel can not be magazine fed at a jump less than 0.080" although there are some (SPEER 80g) bullets that have an ojive very near the point that I have not explored enough to discount.
Shooting position and form are important, consistency is important. Trigger pull is important. So far, I have tried tight holds, loose holds, free-recoil (had a little better accuracy - sometimes), and what 'just feels right'. I'm using a high quality bipod and a sandbag under the butt. I've got pointing wobble down to <0.25 MOA, and recoil is only moving me about 2 MOA up-left (gotta time the muzzle brake I guess). The new trigger makes it easier to shoot better (feel better about each shot being fired correctly).
The barrel pointing toward the exact same place the scope reticle points shot to shot is a function of mechanical design and execution. I think I've accounted for and eliminated every source of shot-to-shot variation.
The bullet hitting where the barrel is pointing is a function of powder burn rate (gas conversion rate), barrel position at the moment the bullet exits the barrel, and external ballistics (wind mostly). I'm still having problems I think in this area because I can't get the consistency I see in my 308, 6.5 CM, or 204. (I have tried turning off the gas port to make the AR a single shot, although it was a while ago, I didn't see any better ES). I'm starting to think the problem is the cartridge and chamber design.
But! There are manufacturers (including Proof Research - who will get a chance to address this directly soon), who deliver sub-MOA accuracy as a function of build quality. They sometimes use the same parts my rifle is built with, so why isn't mine working?
I host a web site (http://SnellsNotebook.us) where I have collected what I think are the facts as well as techniques that work for creating accurate ammo. When I finally unravel the last bit of technique to bring this rifle down to sub-moa and keep it there, I will write an article (maybe re-write this one) to include whatever else I find out out, and how it works.
First I scoured the PRS blog, and YouTube then poked around here and there for nuggets of truth.
Here's what I think I know at this point.
1. The BARREL is the most important item. It must be a high quality barrel. The chamber must be installed by indicating on center, then reaming with a piloted reamer. Experience counts. I purchased a discontinued Proof Research button rifled 16" barrel after calling Proof to confirm that they stand behind its accuracy.
1A. The barrel must be seated to the upper correctly. This requires most uppers to be squared using lapping compound and an inexpensive tool (if you own a lathe, make your own, if not look at Wheeler for a kit).
1B. The barrel must not move between shots. Restated, the barrel must 'point' to the EXACT same place every shot.
1C. You can use Locktite 620 (green) to glue the barrel extension into the upper. If you do, you will have to use a torch to heat the upper to more than 500F to remove it, and you will probably have to burn the Locktite off the barrel extension to clean it up if you plan to reuse the barrel. I know this because my first barrel was a STAG 24" Varmint barrel that simply would not shoot under 1.5 MOA. If you Locktite the barrel it WILL NOT MOVE regardless the barrel nut torque applied.
1D. If you do not use a glue, then use a copper infused anti-seize (NAPA). On my second barrel (the Proof Research) I changed gas system and handguard, which changed the barrel nut to a hex nut (I LIKE the hex nut, I don't like the cost of a 1-1/16" crows foot to fit the torque wrench!). Using the SEEKINS barrel nut, I first tired 50 lb-ft torque. Got 1.5 MOA. Then 65 lb-ft the barrel nut moved about 3 degrees as I brought it up (always increased torque, never backed nut off), the nut moving did not affect the gas tube alighnment, but in a conventional barrel nut (with gas tube holes) it would have been a poblem. At 65 lb-ft 1.5 MOA continues. Eventually bumped it up to 75 lf-ft and expect to leave it there. It does not appear that torque changes (above 50 lb-ft) have any affect on accuracy with my barrels (I did something similar to the STAG 24" Varmint barrel, it turns out that barrel had it's chamber installed (wait for it … ) 1-2 MOA out of true. I know because I cast the chamber and measured.
2. The TRIGGER is the second most important piece of hardware. "Everyone" says so. I started shooting competitively at age 7 and was a contender for the US Olympic Team the year I won the Southeast Asia lottery. I've got an 'educated' trigger finger, and I can shoot any military trigger at expert level. I didn't want to believe a 'better' trigger would make $200 worth of difference. Recently I bought a TRIGGER TECH AR15 ADAPTABLE trigger. It's a two stage with the first stage takeup about the same as the center blade on a Savage AccuTrigger. I adjusted the trigger to nearly it's lowest weight (2.5 lbs). This trigger really does feel like a quality 1911 trigger when it breaks. I can't prove I shoot any better with it, but I think I have a slight improvement in eye-hand (trigger finger) coordination that may be worth 0.25MOA in 'pointing where I want it to go off'. The hammer is a bit faster so lock time is probably a bit quicker (always a good thing), and I believe that (faster lock time) is the big improvement for me. Anyway the trigger feels so good that I think its worth the cost, even if it doesn't show up as any better groups for me. For someone without the 'couple million' trigger pulls's I've done, this trigger may very well create a measurable improvement in accuracy.
3. SIGHTS. In International Smallbore and Service Rifle competition we used iron sights to make 0.5 MOA corrections that were measurable and repeatable. The days when my eyes could do that are long gone. Now I use a scope exclusively. I used to have a lot of different and very expensive scopes on my rifles. Then Vortex came out with the DIAMONDBACK TACTICAL 5-25x50 FFP and priced it well below its performance point. I traded in all my NightForce, Burris, and other scopes to replace every one of my scopes with the same model. Now I only have to learn one reticle, one set of adjustments, one … well you get the idea. So when this rifle (wearing that scope) would not shoot well (back when it was the STAG barrel), I used my 308 and 204 to 'qualify' their Vortex Diamondback scopes with TALL TARGET and BOX tests so I knew the scopes were working correctly, predictably, and by how much to correct for 'click' error. Then I took the scope off my 204 (it's a consistent 0.3 MOA rifle) and swapped with the AR scope. No change, still getting 1.5 MOA on the AR. The AR's scope is now on the 204 and is consistently printing sub-half MOA. The mounts on the bolt guns are massive tactical style attachments, while the AR has a Vortex 'cantilever' scope mount. The jury is out about this mount, but I know I need to keep the scope forward and high and attached on the upper (never the forened) to ensure it doesn't move between shots. I had some 'issues' with the Vortex mount to start with that I solved by boring out the holes for the screws that apply gripping pressure to the PIC rail. I also used some of that Copper infused anti-seize grease to ensure the clamp would move into its tight position without restriction or excess friction, and of course I torqued it to spec. I'm 'pretty sure' this mount isn't the problem.
4. GAS SYSTEM. The gas tube must not be under any tension when the bolt is closed. If it is, then when the bolt moves, the barrel will move, and not in a uniform way. You can check this easily when building by watching the gas tube while closing the bolt, you can also smoke check the gas tube to gas-key fit to ensure there is no lateral pressure. In my latest configuration I am using an adjustable gas block that has set screw that coordinates with a dimple in the barrel to set the gas block location correctly. if you use a clamp style gas block, keep in mind that the block should not touch any shoulder on the barrel. The AR15-A1 hand guard had a 0.015" thick steel plate that was captured between the gas block and that shoulder. Your gas block should install with a 0.015" gap if there is a shoulder.
4A. While we are on the subject of the gas system, using an adjustable gas block should improve your accuracy by reducing the stresses transmitted though the system. Lower gas pressure in the gas tube, gas key should allow the bullet to exit the barrel well before the bolt carrier group begins to move.
4B. An instructive test of your gas system works like this: (Be sure your rife is unloaded! Have a safe landing zone for your BCG!)
1. With the upper removed from the lower.
2. Remove the Charging Handle and the BCG.
3. Reinstall the BCG without the Charging Handle.
3 . With the bolt carrier group fully forward, and the bolt in full lockup.
4. Apply compressed air to the barrel at the muzzle.
You will likely be very surprised at how little air pressure it takes to unlock the bolt, and toss it out the back of the upper. If you wanted to get the system wet, you probably could easily do this with your lungs!
Anyway, you can use the changes in the sound of the air as you manipulate the BCG to get some idea what the relationship of the gas tube to gas key is. Keep in mind that gas ports through the gas key to the right side of the BCG.
5. LOWER. There is very little other than the trigger about the lower that affects accuracy directly. As long as the lower fits well enough to fire the rifle it should be capable of good accuracy. That's what my brain says. When I hear the upper/lower rattle, when I feel the upper/lower move around, I just don't feel accurate. There is a very good and simple fix. WHEELDIAMOND (.com) produces a little horseshoe shaped piece of Aluminum that you can fit to your upper that will (if correctly installed) totally eliminate all movement between the upper and lower. I absolutely love mine. I guess things that make you feel better might make you shoot better, it's not going to make the rifle shoot any better though.
6. AMMO. In order of importance this is probably really number one or two. Barrel manufacturers will guarantee accuracy only with match quality factory ammo, because if the ammo is inconsistent, the accuracy is inconsistent. However consistent ammo alone can not make a rifle accurate. My Proof Research barrel has a 1:8 twist. It should be good for 55-75 maybe 80 grain or heavier bullets. So far hand loads and factory match ammo from Black Hills and Hornady are still not consistently sub-MOA regardless the bullet weight. Some are atrocious! For example XM855 will not shoot consistently below 2 MOA (which used to be ok for National Match, but I'm looking to hit ground squirrels at 300+). Black Hills consistently shows ejector swipes on the case head (over pressure), and has not shot well in any of my barrels, HORNADY MATCH is not shooting sub-moa, and my handloads, mostly using CFE223 have not been impressive except for velocity. I use QuickLoad, a lot of loading manuals, and direct measurement to understand a load. I've found setting up QL for 5.56 NATO and using the actual case volume of water has allowed me to work in a much higher velocity range than most manuals recommend. My PRESSURE TRACE confirms the QL predictions for pressure, and my LAB RADAR is right in line with QL velocity predictions. Thing is, I am not having a good time getting ES (extreme velocity spread) down to below 50 fps. Typically in 10 shots of a given load the ES wiil be 100-200 fps. I've tried sorting for case volume, more powder, less powder, crimp, no-crimp and neck tension adjustments with nothing pointing to a 'better way'. I've loaded one-at-a-time in a single stage press, and 'production-mode' on my Dillon XL650. I seem to be able to get Dillon loads that work as well as any I can load single-stage. Neck turning didn't improve group size either, but it did improve concentricity. I've measured runout on loaded ammo, then cycled it through the rifle from the magazine by dropping the bolt from bolt-lock. My adjustable gas block is set to 'just work' plus 'a little' which shoots soft and reliably. One would think the difference between bolt-lock and shot-to-shot loading would be minimal. Anyway the runout of 'cycled' ammo is the same as it was before loading it into the rifle. I've marked up bullet noses to check for contact, and only see very light scratches, and left or right feed appear the same (but on opposite sides of the bullet). At present, I'm chasing a 5 shot 0.4MOA group that probably was a statistical anomaly. It was a Hornady 40g VMAX load. I think the 40g VMAX may shoot very well in this rifle, and the latest round of testing though mostly 1.0-1.5 MOA the groups were more round and group size vs charge was more consistent than previously. My memory is 'itching' telling me there is a chance that flyers are coming from the 3rd and 5th shots more often than not. Don't know what that means yet, if anything.
CONCLUSIONS:
The sub-MOA AR15 may not be a 5.56 NATO (or Wylde) rifle. All of my very accurate guns have the ability to load the bullet to zero jump, and find their highest accuracy at a point less than 0.050" of jump. My AR15 barrel can not be magazine fed at a jump less than 0.080" although there are some (SPEER 80g) bullets that have an ojive very near the point that I have not explored enough to discount.
Shooting position and form are important, consistency is important. Trigger pull is important. So far, I have tried tight holds, loose holds, free-recoil (had a little better accuracy - sometimes), and what 'just feels right'. I'm using a high quality bipod and a sandbag under the butt. I've got pointing wobble down to <0.25 MOA, and recoil is only moving me about 2 MOA up-left (gotta time the muzzle brake I guess). The new trigger makes it easier to shoot better (feel better about each shot being fired correctly).
The barrel pointing toward the exact same place the scope reticle points shot to shot is a function of mechanical design and execution. I think I've accounted for and eliminated every source of shot-to-shot variation.
The bullet hitting where the barrel is pointing is a function of powder burn rate (gas conversion rate), barrel position at the moment the bullet exits the barrel, and external ballistics (wind mostly). I'm still having problems I think in this area because I can't get the consistency I see in my 308, 6.5 CM, or 204. (I have tried turning off the gas port to make the AR a single shot, although it was a while ago, I didn't see any better ES). I'm starting to think the problem is the cartridge and chamber design.
But! There are manufacturers (including Proof Research - who will get a chance to address this directly soon), who deliver sub-MOA accuracy as a function of build quality. They sometimes use the same parts my rifle is built with, so why isn't mine working?
I host a web site (http://SnellsNotebook.us) where I have collected what I think are the facts as well as techniques that work for creating accurate ammo. When I finally unravel the last bit of technique to bring this rifle down to sub-moa and keep it there, I will write an article (maybe re-write this one) to include whatever else I find out out, and how it works.
