Achieving accuracy with barrel rifling basics
For competitive shooters, consistent accuracy is the pot of gold at the end of the rainbow. However, to achieve ultimate precision shot-after-shot you first have to understand and perfect a range of factors that affect accuracy.
Here, we’re going to discuss just one small piece of the puzzle; barrel rifling. To detail how barrel rifling can help enhance your .22LR accuracy, Paul Tolvstad - small-bore precision barrel maker, benchrest shooter and member of the KSS team – explains.
Different types of rifling can have a huge impact of accuracy. Let’s first break it down to what is barrel rifling. Simply put, rifling is the arrangement of the grooves found inside the surface of a rifle barrel.
When a rifle is shot, the helical grooves cause the bullet to spin creating stability and improving both range and accuracy. Without spin, you lose accuracy. There is, of course, a downside to this. In order to generate spin, the bullet must contact the barrel meaning that by the time it leaves the barrel the surface is no longer smooth and creates drag. This makes it easier for the wind to affect the bullets path.
To help counteract this, modern day rifling techniques are no longer square which used to create sharp corners on the cartridge. Today, rifling patterns are designed to keep the bullet as smooth as possible. There is a fine balance needed to ensure there is enough grip with create spin, while not affecting the surface as much as possible.
For benchrest shooters, finding the perfect balance is a challenge. We want to generate enough spin for a straight pathway to the target, but limit the amount of contact to reduce drag levels.
The most commonly used barrels in rimfire benchrest include:
- Shilen: 4 groove ratchet, 8 groove octagon
- Muller Works: 5R, 4 and 8 minimally invasive (MI)
- Benchmark: 2 and 3 groove
- Broughton: 4 and 5 C’s
- Douglas: 4 groove
The Muller 4 and 8 groove barrels have a skinnier land with no sharp corners which is why they use the term minimally invasive. The Broughton 4 and 5C are very similar to the 5R rifling profile. Benchmark 2 and 3 groove and Douglas 4 groove have a standard square rifling pattern. Although the most dominant in benchrest are the Shilen 4 groove ratchet and the Muller 4 MI, all have had success in big matches.
The variation between rifling types is one reason why batch testing your ammunition is so important to achieving accuracy. Here at Killough Shooting Sports, we’re lucky enough to have an ELEY test range of site designed to eliminate variables and help you find the right fit for your barrel.
Find out more about the ELEY test range here in Texas and book your next visit to ensure absolute accuracy when you next take to the range.
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