Posted: 10/9/2012 1:01:51 PM EDT
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PSA (and or any browsers of the forum)
Today I took out my 20" that i recently received from you guys. I was short on time so I could only make it out to the local indoor range. At first all was fine, besides being wildly inaccurate (thought it was user error at first) After about 50 rounds and a target change, I shot a few more using the bench as a rest: Here was the group I came back with: http://s7.postimage.org/8b9zanu1n/IMG_20121009_154952.jpg This was at 19 yards(as far back as i could go) Now i'm not a competition shooter, but I can put groups significantly better then that on paper with some of your other uppers at 100 yards - keyholing aside. I figure that it is the ammo and will update as soon as I can try with other brands, but I wanted to know if this warranted enough concern to get looked at. Here are the variables: Rifle: PSA 20 inch CMV 1/7 MP CL upper PSA M16 BCG Comp M4s Rock River Lower w/ a2 buffer setup Ammo Freedom Munitions brass cased 55 grn FMJ m193 Remanufactured.(I know its a cheap buy, but it has fed and fired flawlessly in all my other weapons after about 1500 rounds) Let me know, TIA! |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. Thanks for the advice. I think i'll take her out to the long range tomorrow if I have time and report back. I hope this doesnt come off as a PSA bash thread because I'm thousands of dollars deep in their products - I just want to make sure the error is on my end. |
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Uhhhh, shooting at 100 yards isn't going to fix that bullet that's nearly completely sideways and several inches off the bull. I'd try different ammo anyways just to be sure before proceeding. I couldn't see the picture when I first posted. From how bad the group is, I think my hypothesis is wrong. OP, try some different ammo, preferably a 62-75 grain bullet. If that doesn't help then there is something wrong with the barrel. |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet.  what!? 
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. what!? Have I been mislead? That is what I have been told regarding overstabilization of a bullet due to the rate of twist being to fast for a certain length bullet... |
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Freedom Munitions brass cased 55 grn FMJ m193 Remanufactured.... We do not recommend the use of remanufactured ammunition in our uppers. Because the barrel twist will consistently spin each bullet, and only a few rounds are affected, it would be evidence of an inconsistency in the ammo. Please try some brass cased, first run ammo from a domestic manufacturer. If you continue to have an issue with the upper, please contact CS, they will gladly take care of it. |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. What???? There is no such thing as "overstabilization". Did you mean something else? |
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Freedom Munitions brass cased 55 grn FMJ m193 Remanufactured.... We do not recommend the use of remanufactured ammunition in our uppers. Because the barrel twist will consistently spin each bullet, and only a few rounds are affected, it would be evidence of an inconsistency in the ammo. Please try some brass cased, first run ammo from a domestic manufacturer. If you continue to have an issue with the upper, please contact CS, they will gladly take care of it. Thanks PSA. Will report back tomorrow. |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. This guy does not know what the hell he is talking about 
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. What???? There is no such thing as "overstabilization". Did you mean something else? http://www.nennstiel-ruprecht.de/bullfly/fig15.htm A buddy of mine was talking about shooting a 35 grain bullet in my 1/8 twist barrel. He sent me this link and said that the bullet can overstabilize causing the bullet to yaw. At least that is how it was explained to me. Perhaps he was mistaken? |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. What???? There is no such thing as "overstabilization". Did you mean something else? http://www.nennstiel-ruprecht.de/bullfly/fig15.htm A buddy of mine was talking about shooting a 35 grain bullet in my 1/8 twist barrel. He sent me this link and said that the bullet can overstabilize causing the bullet to yaw. At least that is how it was explained to me. Perhaps he was mistaken? and is fired at a high angle of departure, especially when fired vertically. An over-stabilized bullet on a high-angle trajectory lands base first... but must be considered when firing at high angles of elevation.
This is why "overstabilization" is a non-issue with AR-15s. The problem really does not exist, especially with the currently available twist rates. |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. What???? There is no such thing as "overstabilization". Did you mean something else? http://www.nennstiel-ruprecht.de/bullfly/fig15.htm A buddy of mine was talking about shooting a 35 grain bullet in my 1/8 twist barrel. He sent me this link and said that the bullet can overstabilize causing the bullet to yaw. At least that is how it was explained to me. Perhaps he was mistaken? and is fired at a high angle of departure, especially when fired vertically. An over-stabilized bullet on a high-angle trajectory lands base first... but must be considered when firing at high angles of elevation.
This is why "overstabilization" is a non-issue with AR-15s. The problem really does not exist, especially with the currently available twist rates. Ah... I skimmed over that little tidbit. |
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In a gun with a 20" barrel , a 1/7 twist and 55 grain bullets the bullet will be overstabilized and can definitely cause a keyholing effect. This would be especially true at only 19 yards. Try to shoot it out at 100 yards and I would be willing to bet there would be no keyholing. It would give the bullet time to slow down somewhat when speaking about the rotation of the bullet. What???? There is no such thing as "overstabilization". Did you mean something else? http://www.nennstiel-ruprecht.de/bullfly/fig15.htm A buddy of mine was talking about shooting a 35 grain bullet in my 1/8 twist barrel. He sent me this link and said that the bullet can overstabilize causing the bullet to yaw. At least that is how it was explained to me. Perhaps he was mistaken? and is fired at a high angle of departure, especially when fired vertically. An over-stabilized bullet on a high-angle trajectory lands base first... but must be considered when firing at high angles of elevation.
This is why "overstabilization" is a non-issue with AR-15s. The problem really does not exist, especially with the currently available twist rates. Ah... I skimmed over that little tidbit. Yeah... Otherwise I must admit that was an interesting read, and it may explain the misinformation regarding "stabilization" with the AR-15 platform. |
