Rifle shooting

[Peter_HMR]

Was asked in college by our computer lecutrer to right a 2000 word essay on anything at all. Naturally everything was left to the last night and all i could think about was hunting so decided to right the essay on that anyway just thought id post it up.

 

In this essay I would like to deal with my favourite sport and hobby, shooting. There are many different aspects and approaches to shooting. Here I would like to deal with my own experiences and disciplines.

I currently have 3 guns, a Browning semi-automatic shotgun, a CZ bolt action rifle and a Brno semi-automatic rifle. Each gun has a specific use and set of licensing requirements attached to it. In this essay I would like to deal with rifle shooting and give you an idea of the make up of a rifle, how it functions and how a rifle is properly setup.

A rifle is a precision instrument designed to fire a projectile in this case a bullet within its range and to maintain a high level of accuracy.

The main and most important feature of any rifle is its barrel, this is where the cartridge is inserted and discharged and where the bullet gathers velocity and stabilises. The barrel is usually made from steal from a process called hammer forging, it is long and shaped in the form of a cylinder. The centre is bored out to form the bore of the rifle and is specific to the calibre of bullet the rifle is designed for. At the start of the barrel is the chamber this is designed to accommodate the cartridge which is normally wider than the bullet and it is where the bullet is discharged from. The bore of the rifle has groves along it called the rifling these are lines etched into the bore starting from the end of the chamber and continuing to the muzzle the number of them is specific to the calibre of bullet being used and the velocity it will reach. They are designed to rotate the bullet as it gathers velocity which stabilises it while it travels through the air. At the other end of the barrel is the muzzle, this is where the bullet exits. There are quite a few different designs some where the muzzle surface is machined perpendicular to the line of the bore others at an angle to it and some rounded, the most important fact is that it is uniform so that there is no interference as the bullet exits the muzzle.

Behind the barrel you find the action this houses the mechanism which delivers the cartridge into the barrel and the firing mechanism. I use a bolt action rifle and a semi-automatic rifle. Both actions use a bolt one is operated manually the other automatically taking advantage of the recoil of the bullet to cycle itself. The bolt slides back and forward inside the action on groves which hold it in place. When the bolt is slid into the reward position it exposes a round in the magazine the bolt is then pushed forward where it catches the round pushing it up into the chamber it is then closed in place either automatically by the force of the spring or manually by rotating the bolt handle down. This process locks the bolt with a round inserted in the barrel and also cocks the firing mechanism making the gun live. The firing mechanism consists of a firing pin housed in the bolt and a trigger mechanism which on a bolt action is designed to release the firing pin which is held under pressure by a spring or on a semi-auto which is designed to strike the firing pin by releasing a hammer.

Both rifles use telescopic sights or scopes which are mounted to the gun via a rail which is formed on the top of the action. The scope consists of a series of lenses housed in an aluminium tubular structure and is designed to magnify the target and it has a cross hairs which is used to aim the rifle. They come in a wide variety of configurations but all essentially do the same thing, point the gun in the right direction.

As I mentioned before I have 2 rifles. The first one is a CZ bolt action rifle it is chambered in .17hmr and is used as a hunting rifle. It projects a 17grain .172diameter bullet at 2550fps and achieves a kinetic energy of 245ft lbs at the muzzle. It uses a copper coated lead bullet with a polymer tip which is designed to fragment upon hitting anything causing maximum energy transfer and extremely damaging results to anything it hits. It is a very accurate rifle and will achieve 1/2inch groups at 100yards. It is scope with a Mueller APV which has a 4.5-14x magnification band and an objective diameter of 40mm. The gun/ammo combination is capable of shooting accurately out to 300yards however if the gun was pointed at a 45degree angle the bullet will travel out to nearly 2miles. It is suitable for shooting small quarry ie rabbits and other small varmints out to 250yards realistically and medium sized quarry ie foxes and other sized animals to 150yards.

My second rifle is a Brno semi-automatic rifle chambered in .22lr and will be used mainly as an informal target shooting rifle or in other words a plinking rifle. It projects a heavier 40grain .224diameter bullet at either 1050fps (sub sonic) or 1150fps(supersonic) and achieves a kinetic energy of 140ft lbs at the muzzle. The bullet is normally soft lead hollow point bullet designed to rapidly expand on impact and tumble to transfer its energy. There are lots of different loads are available as mentioned there are subsonic loads so that the bullet doesn’t reach the speed of sound (1100fps) and create a sonic boom which to the shooter is a sharp crack. The advantage of this is a much quieter gun which won’t alert your quarry. I am still waiting for the licence to come through so as of yet haven’t shot it but would hope the rifle to achieve 1 inch groups at 100yards which is its effect maximum range on quarry while larger fox sized animals should only be shot out to 60yards.

For any rifle it is critical that is it setup right and is zeroed at the required range. There are a couple of things that can be done to maximise the accuracy out of any rifle. On my CZ I have modified it in a couple of ways. The first thing I did to it was to free float the barrel this is a fairly simple idea it involves sanding out the barrel channel of the stock to insure that the metal surface of the barrel doesn’t come into contact with the wooden stock at any point. The first thing to do is to remove the barrelled action from the stock. Then using some coarse sandpaper and a wooden dowel of the same diameter of the stock any material that would come into contact can be removed. Some finer sandpaper is then used to smooth out the channel and the wood then has to be sealed to protect it from water and oil damage. This is done to maintain the consistency of the barrel, if it is touching the wood then changes in humidity can affect the wood which will move the barrel. While this may only change the point of impact by and inch or two in some cases it can mean the difference between a kill or wounding the animal which is not acceptable.

The second modification I did was done to the trigger. To get the most accuracy out of the gun a smooth trigger is preferably by most shooters with little or no take up and a crisp break. The trigger design of this gun is a single stage trigger and before the modification there was a certain amount of creep or slack in the trigger before it released. I removed this by putting a brass shim in front of the sear to reduce the engagement between the trigger and the sear and effectively eliminate and creep in the trigger. I also lightened the trigger by replacing the spring for a lighter one. This means that when the crosshairs are on target and I pull the trigger there is no movement just a crisp release.

The most important part of setting up a rifle is to zero it. This means that you have to calibrate the scope so that the cross hairs are aiming where the rifle is shooting. It is a simple enough process the complications arise when deciding on what distance to zero the rifle at. When the bullet leaves the muzzle it does not as most people would think fire in a perfectly straight line it forms a parabolic curve due to the influence of gravity on the bullet. The scope on a rifle is generally mounted approximately 1 1/2inches about the muzzle. As the bullet exits the muzzle it rises up to the point of aim (POA) which is the sight line of the scope, it will then cross the line rising above it and then fall through it again on its path towards the ground. When choosing a zero for the rifle you want to take advantage of the straightest part of the curve so that the bullet is never very far away from the POA thus making it easier for the shooter when shooting over a variety of distances. The best distance to zero a hunting rifle in is the centre over the band of distances you’ll be shooting over. To zero a rifle you set up a target at your chosen range in this case 100yards. You then fire a few shots on target to see the point of impact (POI) of the bullet. In my case the bullet was hitting the target 15inches to the right and 8inches low. You then shift the point of impact of the scope one axis at a time. The standard for most scopes is ¼ MOA (minute of angle) per click which in this case is ¼ of an inch at 100yards. To adjust for the vertical axis which was 8inches low you would count 32clicks up on the scope to align it and on the horizontal axis 60clicks to the right to align it. You continue the process until the POI is the same as the POA or in other words that the gun is shooting where the scope it pointing.

The .17hmr is a very fast round and consequently has a very flat trajectory out to its effective range. My chosen zero is 100yards. When the bullet leaves the muzzle it is 1.5inches below the POA it then rises and crosses the POA at 43yards, it continues to rise to 0.4 of an inch at approximately 65 yards it maximum height and starts falling, it crosses back over the POA at 100yards, falls 0.9inches below the POA at 125yards, 2.59inches at 150yards, 8.54inches at 200yards and continues falling till it reaches the ground. This means that when shooting quarry that between 25yards and 125yards the bullet is within 1inch of the POA which allows you to point the crosshairs at an animal and without having to compensate from bullet drop you can just shoot. Moving out to longer ranges ie past 125 the shooter is required to compensate for bullet drop. Range finding at is critical as if you don’t know what range your shooting at you won’t be able to compensate.

Different shooters adopt different techniques for rifle shooting. Breathing plays an important role and being calm and relaxed is extremely important. My method is exhale with the crosshairs below the target taking in a deep breath and allowing the cross hairs to rise up along the target and squeezing the trigger as you come to the point where you want the bullet to impact. The important thing is consistency, using the same hold over the gun and using the same method each time to ensure that each time you fire the gun the bullet.

The most important part of any aspect of rifle shooting is to have your rifle properly setup that you are familiar with it and how it works and most importantly knowing every time when you pull the trigger exactly where the bullet will go.

[steve_k]

very good

nice read

classic essay planned out there good stuff...