drop down to a 55gr or under and it will stop keyholing.
Why haven't we stickied this topic to the FAQ yet?
1:12 is too slow for anything over 60gr. You need atleast 1:9 twist to shoot 69gr bullets.
The 1 in 12 will definitely do better with 55gr and under. I'd think a benchmark factory load would be the Federal American Eagle 50gr JHP (AE223G). It's an economical tack driver for slow twist .223 barrels.
55 grain and under is best for that twist rate.
I would imagine the 50-55gr bullets would do really well there.
Something like these:
Hornady V-Max 53gr
Sierra MatchKing 52gr
MidwayUSA Dogtown 50gr
Something like these:
Hornady V-Max 53gr
Sierra MatchKing 52gr
MidwayUSA Dogtown 50gr
2 things, (one on topic the other isn't but not enough for a thread)
what is keyholing, and how do you over stabilize a bullet?
Keyholing is when the bullet travels through the air (and the target) at an angle that is not paralell to the barrel. Think of it traveling through sideways, leaving a hole that is a profile of a bullet, not a hole.
This happens when the bullet is not spinning fast enough to maintain longitudinal stability after it leaves the barrel. It may start as a wobble and get progressively worse, or it may not spin at all because there is not enough twist to get the bullet spinning. It can also be caused by passing through one target, then another.
As an example, my light loads will cause a perfectly round hole in the front of a 55 gallon drum, but the hole in the rear of the drum is a keyhole because the front of the barrel causes distortion.
One solution is to reduce the amount of mass that must be spun in the given number of twists that are available. The way to do this is to reduce the weight of the bullet. thus going below 55 grains gives a bullet of sufficient weight to carry enough energy to effect the target, but not so much that the rifling in the barrel cannot get it spinning.
Over-stabilizing is causing the bullet to spin so fast that it causes either separation of the jacket (unlikely, but it does happen), or causing such a gyroscopic effect that the bullet begins to curve under the force of the effect. Neither are very likely.
This happens when the bullet is not spinning fast enough to maintain longitudinal stability after it leaves the barrel. It may start as a wobble and get progressively worse, or it may not spin at all because there is not enough twist to get the bullet spinning. It can also be caused by passing through one target, then another.
As an example, my light loads will cause a perfectly round hole in the front of a 55 gallon drum, but the hole in the rear of the drum is a keyhole because the front of the barrel causes distortion.
One solution is to reduce the amount of mass that must be spun in the given number of twists that are available. The way to do this is to reduce the weight of the bullet. thus going below 55 grains gives a bullet of sufficient weight to carry enough energy to effect the target, but not so much that the rifling in the barrel cannot get it spinning.
Over-stabilizing is causing the bullet to spin so fast that it causes either separation of the jacket (unlikely, but it does happen), or causing such a gyroscopic effect that the bullet begins to curve under the force of the effect. Neither are very likely.
