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Posted: 2/1/2003 8:54:34 PM EDT
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I have issues with Armalite 223 accuracy. (1/9 twist) It is generally a very accurate rifle but when I shoot off sandbags and press too hard on the rifle in order to get it rock-steady and not moving, all accuracy goes to hell. I mean, I get 10" patterns at 100 yards. It is a pattern, not a group. It took me a while to figure this out... I would adjust the scope say 8" up, then shoot off hand and the groups wouldn't even be on paper. What's going on, am I bending the barrel? Just the other day I was shooting off sand-bags South African ammo and was getting weird groups again. Even though I was trying not to exert any downward pressure on it. This is the same rifle I've gotten 3/4" groups with, but with better ammo like Win Q3131, although even the best ammo sometimes shoots just as weird in it. It seems to do very well, sub-MOA accuracy when it's just laying on the sandbags but push it down a bit and doesn't group at all. |
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Quoted: What's going on, am I bending the barrel? YES!!!! This is why float tubes were designed. The tubes allow you to sling up as tight as you want to, or apply pressure downward, and still not effect the barrel/sight POA. [url]http://www.armalite.com/index-old.htm[/url] Free Floating barrel sleeve, rifle EMNM04 $133.00. If your looking to keep the rifle looking stock and DCM legal. P.S. The rifle will shoot it's best all by it's self. Which means the less input you put into the rifle, the less chance of you being the unstable variable. Dano |
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FALARAK, I have seen worse than that off the bench. Granted that barrel harmonics will only play a small roll in the group, it's the shooter’s input that causes the change in impact. When the rifle is fired, the muzzle/rifle is going to rise. If he is fighting/trying to overcome the rise/movement of the rifle, then where the muzzle ends up when the bullet exits, is not a constant. Also, add to the fact that he may be putting pressure on the mag and the bolt may not be locking the same way from shot to shot, due to bolt/ammo/mag binding. The biggest problem with novice bench shooters is that they try to fight the rifle, instead of putting the minimal input into the rifle. The shooter is always the non-constant variable. ad_nauseam, If you’re going to bench the rifle, bag the front, bag the rear, then use your forearm hand on the butt of the rifle, just under the butt and against your chest. Also, don't put a death grip/face plant on the rifle; all this will do is translate your pulse/body movement to the rifle. By lightly gripping the rifle, you minimize your variable input/distortion, and allow the rifle to work with it's own harmonics, and not the deviations/random inputs that you are transferring into the rifle. Dano |
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[b] FALARAK [/b] It does that. If I push on it considerably, it doesn't even group. [b] A_Free_Man, [/b] I haven't tested it off-hand with a sling. [b] Dano523, [/b] I followed your advice above about "putting the minimal input into the rifle" and got, at 100 meters: (mostly 2-shot groups) M855 0.63" 1.05" 1.32" 1.85" 2.19" 4" (probably pushed it against the sand-bags too much) WCC: 1.6" 1.72" 1.75" Overall, it seems to be about 2 MOA rifle, which is kind of Okay... But, I do recall that I've gotten 0.4" 2-shot groups with good M855 ammo... So it has potential but I am not sure how to get it out consistently even by following the aforementioned advice. |
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ad_nauseam, We may not have covered this, but take off the hand guards and grab the front sight tower. Try to twist the sight tower and look at the delta ring/upper receiver for any movement in the barrel. I just want to make sure that your barrel is tight in the receiver. Now for the facts, a group is ten shoots, not just two. To group, Starting with a clean rifle/bore, load 11 shots in the mag and charge the rifle. Put the first round into the dirt bank (off target). The first shot will be a fouling round. Now take your time and put the remaining 10 into the target. Make a note in your mind if you pulled any shots and how many. Now change the target and clean the bore of your rifle again, and load up 11 more rounds of the next type of ammo that you will be testing. Again, use the first shoot to pre-foul the barrel, then the remaining ten to group. Once you have a few ten shot groups, and then get back to us regarding the group size. Regarding your two shot groups, just charging a round by hand out to the mag can cause a flyer. If your first shots where by cocking, then your second by the action cycle, it won't tell you anything. Now for the bad news, the fact that you are using factory ammo, and you have a production rifle, your going to find that the rifle will produce a 1-1/2" to 3" group with a ten shot string. The contributing factor will be that the load is not tailored for the barrel (whip/harmonics), the bullet (octave) may not be even close to the lands for clean engagement (long throat), your trigger pull may leave a lot to be desired, your sights may need a lot of improvement... And, add to the fact that it's wintertime, and gunpowder has a mind of it own when it's cold, you could be producing a few 4" groups. Bottom line is if you want an AR-15 that produces sub MOA for a ten shot string, you will have to hand load, and put a lot of money into your rifle changing out parts. For a stock factory rig using factory ammo, you being able to produce groups under a 2MOA on a constanct bases, will put you ahead of over 70% of the shooters in your class. P.s. On your scope, I don't know what brand you are using, but I had one go south on a flat top rig. Every time I shot, the knobs would turn. You may want to mark, or keep a eye on the settings just in case your is having the same problem. Dano |
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Ad Ive had my issues with the same accuracy questions. What has help me quite a bit, is a simple tool to place the rifle on a fixture so as to not have any movement what so ever,I personnly use a black and decker portable work mate bench,I simly open the table top and use it as a holding fixture for the AR, I clamp it to the free floating tube hand guard and place my targets at 100yds ,then I move the table around to fix my cross hairs of my scope exactly on the center of the target, then I simlpy look thru the scope and lightly hold the rifle then press the trigger,Ive been able to see exactly what different rds shoot like,factory or my reloads,Ive been able to eliminate the human body movement and really set my scope and rds for a more consitant moa groups. ------------------------------------------------ Just an Idea |
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