1 in 12 twist 223

[RedTape]

Try loading up some 52grain V-max bullets. Probably wouldn't go over 55 grains with that twist.

 

[Maverick1911]

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.

Yeah....what he said. I have to say, Aviator...you know your stuff.

I would mention that true Varmint barrels are used for shooting smaller animals (ie....varmints ) and generally do not necessitate heavier grain projectiles, just accuracy and effective dissipation of heat after repeated firing. Nowadays some of us want the varmint profile barrel with faster twist rates to hands the heavier grain projectiles....my personal preference .