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Failure to Feed, AR type rifle
See photos below. They show the 2 marks the bolt makes when the round fails to feed. Each photo shows one of the marks.
Rifle is Larue OBR 556, bullet is SMK 77g with CCI 450 primer, 24.9 grains of BLC2, with OAL of 2.255 (pretty long), IMI once fired brass, using Magul magazines. The 24.9 is max load according to Hogden online reload data. I can tell you for a fact it's way to conservative. The action would very often fail to lock open after last round with what I previously used, i.e., 24.5 and 24.7 grains. I shot 50 rounds today and always locks open with 24.9 but did have the one jam which is shown in photos.
No pressure signs and tigther groups with 24.9 grains. I will try 5 rounds maybe tomorrow at 25.1 grains. I might also mention that I had it zeroed with 24.7 grains and when I shot the 24.9 grains POI was 1 1/2 higher, so obviously more velocity which will be good for the range I like to shot at. I was very suprised that a .2 grain increase made such a difference.
I think I might have done a poor job of loading magazine and that is what caused the jam. Those plastic mags are not rigid like the aluminum ones and you can not just tap mag to move round to rear of mag.
It might also be the previous round did not have enough power to completely cycle the bolt. I may just be getting to proper load at 25.1 grains of BLC2. I was told by a friend of mine that those loads are usually 10% to 20% low, and that increasing grains slowly to get best accuracy and velocity is not problem, just check each round for signs of excessive pressure. Also my rifle will shoot NATO spec rounds and pressure is greater than the 223 loading data that Hodgen outlines on their online reloading center.
My reloaded rounds are on the long side and right up against the end of magazine. This may be a problem too.
Does anyone have any other sugguestion of what might be causing this occasional jam.
Rifle is Larue OBR 556, bullet is SMK 77g with CCI 450 primer, 24.9 grains of BLC2, with OAL of 2.255 (pretty long), IMI once fired brass, using Magul magazines. The 24.9 is max load according to Hogden online reload data. I can tell you for a fact it's way to conservative. The action would very often fail to lock open after last round with what I previously used, i.e., 24.5 and 24.7 grains. I shot 50 rounds today and always locks open with 24.9 but did have the one jam which is shown in photos.
No pressure signs and tigther groups with 24.9 grains. I will try 5 rounds maybe tomorrow at 25.1 grains. I might also mention that I had it zeroed with 24.7 grains and when I shot the 24.9 grains POI was 1 1/2 higher, so obviously more velocity which will be good for the range I like to shot at. I was very suprised that a .2 grain increase made such a difference.
I think I might have done a poor job of loading magazine and that is what caused the jam. Those plastic mags are not rigid like the aluminum ones and you can not just tap mag to move round to rear of mag.
It might also be the previous round did not have enough power to completely cycle the bolt. I may just be getting to proper load at 25.1 grains of BLC2. I was told by a friend of mine that those loads are usually 10% to 20% low, and that increasing grains slowly to get best accuracy and velocity is not problem, just check each round for signs of excessive pressure. Also my rifle will shoot NATO spec rounds and pressure is greater than the 223 loading data that Hodgen outlines on their online reloading center.
My reloaded rounds are on the long side and right up against the end of magazine. This may be a problem too.
Does anyone have any other sugguestion of what might be causing this occasional jam.
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