Long Range – What are we missing?
We are creating a rod for our own back in the pursuit of long range performance. But I may have the solution!
Glen Roberts from Precision Shooting Australia once told me that one of the keys to long range shooting was “Choose the highest BC (ballistic coefficient) projectile you can find and drive it as fast as you can!”
It makes a lot of sense – long range shooting is all about accounting for variables, and it is much easier to predict and account for little variables than large variables. High BC and fast velocity results in less bullet drop and less wind drift. While almost all other variables can be calculated and accounted for, wind drift is the one that the shooter must use their judgement and experience to predict. Defeating wind drift is made easier shooting high BC projectiles as fast as you can.
Among other things, velocity is a product of the cartridge case volume and barrel length. The larger the case volume, the more powder you can burn, the more energy you generate and the faster the projectile is propelled. Big volumes of slow burning powder create impressive muzzle flash in short barrels – to utilise this increased volume of powder you need a long barrel.
In recent years we have seen two major “fashions” – long barrels and fast twist rates. Both are following trends towards better long range performance. There are no free lunches with firearm design – what are we forgetting as we move away from more conservative designs? In our journey toward “Bigger, Faster, Longer” we are forgetting elements of firearm design we once considered important.
Accuracy is consistency. Everything needs to happen exactly the same every time you pull the trigger for the bullet to land in the same spot. Vibrations in the barrel caused by the shot firing have a large impact on accuracy – the smaller and more consistent the vibrations the better the accuracy. Long, thin barrels vibrate more. Short, thick barrels vibrate less. It all comes down to how “rigid” the barrel is and rigidity is the key for accuracy.
I’ll summarise and article published on Dan Lilja’s website. (To read more on the topic, visit Dan Lilja’s article on barrel rigidity HERE). Rifle barrels are like a steel beam supported at one end. If you place a weight on the unsupported end of the barrel, the barrel will bend. The amount the barrel will bend is determined by how rigid the barrel is. Short, fat barrels bend little. Long skinny barrels bend a lot. I’m not going to go into the specific physics involved, but every inch added to the barrel makes the barrel exponentially less rigid.
This could be mitigated by making the barrel fatter, but this usually doesn’t occur for three reasons;
1. Barrel manufacturers are restricted in what barrel steel diameters they can use;
2. Actions are restricted in what weight barrels can be fitted to them without damaging the action;
3. Gun owners like to be able to carry and point their firearms (the weight of the rifle).
While twenty years ago a 26″ barrel was considered “long”, it’s not uncommon for barrels to be ordered 30 to 34″ long nowadays. Adding 4″ to a 22″ barrel reduces the barrel’s rigidity by approximately 35%. Increasing that barrel’s length another 4″ to 30″ in length reduces the barrel’s rigidity another 47% and further increasing the barrel length to 34″ reduces the rigidity by another 56%. If you placed two identical weights on the end of a 22″ inch barrel and a 34″ barrel, both having all the same properties other than length, the 34″ barrel would bend 4 times as far! Given that the longer the barrel the thinner the muzzle diameter tends to be to reduce weight, the real world results from testing are likely to be much worse.
It’s this trade off that I’ve been contemplating in recent months – how can we cheat physics to achieve better long distance performance?
The answer has been in a type of shooting I’ve discounted my entire shooting career. Always striving to achieve accuracy while maintaining a classic, aesthetic pedigree left me blind to a sport I considered ugly – Benchrest. Short, thick barrels; small cartridges and ugly rifles. Benchrest shooters achieve accuracy levels unmatched by any other type of shooting – I should have been paying attention to them sooner.
Because of weight restrictions, many Benchrest shooters have always had to juggle the trade-off of barrel length and weight. A common device used in Benchrest is the barrel block – heavy barrels are held in a block halfway along the fore-end rather than hung out of the front of the action. Not only does this prevent the action threads being “pulled”, but increases the rigidity of the barrel.
Barrels are typically held 6-8″ down it’s length. Instead of 24″ of unsupported barrel there is only roughly 17″ of unsupported barrel hung out of the front of the barrel block. The increases in rigidity is dramatic – this example would increase the rigidity of the barrel 248%
This is a serious modification to a rifle. It also goes against what many believe to be a fundamental aspect of rifle accuracy – a free floating barrel. It’s also difficult to implement something like this without introducing variables, like what occurs on Brno rimfire rifles. But it can be done and if done properly will increase accuracy – so why hasn’t it become popular on long range rifles before now?
Is it because long range shooters and Benchrest shooters took entirely different paths toward what each consider “Accuracy”? Is it because the accuracy benefit of a barrel block outweighed the cost and difficulty of installing it into a long range shooting platform? Dan Lilja in his article on barrel rigidity comments “With a 30″ long barrel … Perhaps more than any other rifle type, these rifles benefit from a barrel block.”
It dawned upon me that such an obvious modification would be commonplace if it were as successful as it would seem. Someone must have thought of putting barrel blocks on long range rifles prior to 2017. But let’s not forget the last 10 years in the recreational firearms market have seen the introduction of a huge number of advances in long range shooting; Chassis rifles have only become popular in the last 10 years; Berger introduced the hybrid projectile; Nosler have introduced their own series of long range cartridges; Calibres such as 338 Lapua are now commonplace; Ballistics programs are free downloads for smart phone users; good quality chronographs are affordable to almost any shooter. Introducing barrel blocks into long range platforms will help prevent us hitting a performance ceiling.
I’m currently building two long range rifles – One in 7 x 64 Brenneke and one in 375 Cheytac. Both in McMillan A5 stocks and both with Lilja barrels. We are going to design and fit barrel blocks to them and shoot them at distances up to 2.1km. I’m sure that the results will speak for themselves.
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