Late summer (around here) starts to turn my thoughts toward hunting season. If you have ever gone to the rifle range between now and mid-October, it is a mad house of people checking their rifles and getting ready for the shortly upcoming season. Fall bear season is already open, archery deer season as well as doves start in two weeks.
My range as well as many around the country offer a sight in service, as a fundraiser. This is where the general public can come to the range and pay $5-10 and get help sighting in their rifles. Today I am going to offer some insight to the vocabulary and service.
It all starts with a few basic terms, the first is the bullet. The bullet is the projectile that leaves the firearm with the intent to hit the target. Ideally, it would hit in the same place consistently. Bullets have a whole set of terms that go along with them but let us talk about two in particular.
- Caliber – the diameter of the bullet, typically measured in inches or mm
- Weight – the mass of the bullet. Mass is measured in a unit called grains. It takes 7000 grains to equal 1 pound.
For caliber, the heavier the bullet the longer it is. It is the only way to get the same diameter of projectile with more mass.
Barrels on rifles have a series of lands and grooves inside. The lands are the bearing surface of the barrel touching the bullet as it travels to exit. The pattern is spiral inside the barrel to cause the bullet to rotate and therefore stabilize the projectile.
The number of twists in a the rifling impacts the stability of different weight bullets. So each firearm has some optimum bullet weight for the best potential accuracy because the number of twists do not change.
- Rate of Twist – The number of inches it takes to make one full revolution in a barrel and expressed in a proportion.
For an AR type rifle a 1:7 to a hunting style rifle 1:16. Let us decode a little bit further. 1:7 means one full revolution in seven inches. The faster the twist rate, the better heavier bullets will stabilize, but not necessarily the light ones. Hence, the rifle is optimize to shoot a close range bullet weights based on the twist rate.
Sticking with one caliber, 0.22in nominally AR type rifles typically have a 1:7, 1:8 or 1:9 twist rate. This is going to shoot a 55-65 grain bullet accurately. Using the 22LR, another 0.22in bullet, the twist rate is 1:16 for a Ruger 10-22. Those bullets are ranging from 30-40 grains typically.
We have already gone deep for the uninitiated and we have just touched the surface. What I am trying to get across is that once your rifle is setup and sighted in for a particular load, it is best to use that load for the season. People really in the weeds with ballistics would recommend sticking with the same manufacturing lot because you are likely going to have consistency of the components leading to the most accuracy.
I don’t worry so much about keeping the same lot, but I do understand the principles. Knowing your skillset, how your equipment performs and the territory that you plan on hunting should give you the controllable variables of the hunt. The rest is up to you.
Recent Comments