Rifle barrels uncovered
The world of rifles can be a technical minefield, and gunsmiths like Jonny receive endless questions from confused customers. Here, he begins a series on the basics of rifle buying
We get asked a lot of questions about rifles on a daily basis. This month, I will dabble in this potential minefield, covering a few of the main topics – but please remember that this is an introduction, so the phrase ‘generally speaking’ could be inserted a lot more than it has been.
Many people believe that there is a lot more to worry about technically when buying a rifle than there is when buying a shotgun, from calibre and twist rate to bedding and barrel life. However, my feeling is that if the ultimate questions are ‘does it handle and fit well?’ for a shotgun, the ultimate questions with a rifle are simply ‘is it accurate and is it easy to shoot?’ So really, in essence, buying shotguns and rifles are equally simple!
The first thing I should say with this is that a barrel’s life depends on a vast array of factors. The main one is the degree of accuracy the shooter requires and the ability of the shooter to harness that accuracy. A long-range target shooter of any ability will have stricter tolerances and a lower round count barrel life than the average UK stalker who only requires 2-3 MOA.
If worried about barrel life, it is important to establish a baseline on how truly accurate a rifle is when you first acquire it. To do this properly, you must be capable of touching bullets consistently and have found a load that will make the rifle as accurate as possible. From here, you can measure how large your groups get.
Obviously, the barrel life will start ticking away from the first box of ammo; the speed at which that happens will depend on which loads you put through it, what calibre it is, and how well you look after it. As such, there are no hard and fast rules on barrel life, although it should be stated that more powder equals less barrel life. So, when packing your cases on the loading bench to achieve an extra 100fps, perhaps don’t!
Time for some real life examples:
Person A Howa .243 Stainless Sporter Capable of ½ MOA out of the box, 1,500 rounds saw this rifle doing 1 MOA groups. By 2,200 rounds, this rifle had stretched to just over that, and was sold on (head shooting was a neccessity for this gun). This rifle was shot with factory Norma 100gr only, and only cleaned occasionally, and used for a fairly hard stalking life.
Just a quick aside – the rifle cost £500 new at the time and Norma cost £32/box or £3,520 for all 2,200 fired during its life. Not bad when you consider the actual production cost of a Howa barrel can’t be much more than £50!
Person B Howa .308 Varmint Blued Capable of sub-MOA consistency out of the box. This rifle fired 9,000 rounds of mixed factory, homeload and cheap FMJ throughout its 10-year life, and with regular cleaning only stretched out to 1¾ MOA, but still was generally within this.
Person C Custom 6.5x284 Used for long-range target competition for the first 700 rounds when the rifle was capable of single holes at 100m, then used less so until a round count of 1,000 when excessive throat burn meant the rifle lost meaningful competitive accuracy.
Person D An old Sako Forester.243 This rifle has been owned by D for around 30 years but was second-hand then. Obviously, there were rounds fired before, but accounting just for D’s usage this stands at an estimated 12,000 rounds plus! This rifle shoots 2½" at 100m on a good day, but this is inside the owner’s
‘After shooting, always take your moderator off and wipe your crown and muzzle’
expectations (before anyone judges, the DSC requires 4" and plenty of people just scrape this.)
What can we take away from this? Well, nothing concrete, certainly! As a general rule of thumb, a long-range overbore capacity ‘hot’ round with high accuracy requirements will do around 1,500 minimum, and after that it is down to load and care, with probably 2,500 for retained factory accuracy and 6,000+ is well achievable with adequate accuracy.
I once asked an old-school long-range target shooter how long it would take to wear out a barrel, and he gave me the clever answer of “about 3-5 seconds”. This is how long it takes 4,000 rounds to leave the barrel upon firing. You can use this anecdote if you like, but beware that people might think you are a bit of a muppet!
A final, but potentially less accurate account from a third-hand source, states an old .220 Swift that had been, almost since the calibre’s inception, used with “killing accuracy” for 20,000 rounds. It is romantic tale, which is nice, although the source I got the story from should give it credence, so I couldn’t disregard it entirely.
Loss of accuracy
Seeing as this is rapidly turning into a multi-faceted article, I shall go down the rabbit hole a bit more and talk about what happens to make the rifle lose accuracy.
Throat burn is one of the biggest factors in degrading accuracy. The throat is the tapered part of the lands (the ridges of metal between the grooves of a rifle’s bore). In simple terms, it is the bit of the barrel just after the chamber.
As the throat wears down, the lands also wear away from the chamber. When reloading, you will notice that as a barrel’s life goes, you will have to ‘chase the lands’ moving your seating depth out bit by bit on your reloads. An OAL gauge can be a useful measuring tool for throat wear. As well as the throat extending out, there is also a corrosion aspect that happens in the first 3-4" of the rifling. This takes the form of tiny cracks and pits, and it is this roughness that obviously will decrease consistency as it damages the bullet’s jacket on its way past. This erosion is caused by heat and oxidisation, as well as the actual movement of the bullet and other particles past it at high speed. Throat erosion will kill accuracy well before actual rifling wear makes any difference to accuracy, although long-term it is possible to round off and smooth out the rifling sufficiently to finish a barrel off. It is more than likely that the barrel would have to be shortened from the chamber end, cutting off the eroded end, then be rechambered and refitted to the action to truly wear the rifling out. After throat erosion, muzzle erosion is the next wear consideration. This can take many forms, but the most common cause of muzzle erosion is lack of proper care and maintenance. The main blame goes to moderators – they do catch those gases beautifully in a way to reduce noise, but they also retain the rather corrosive stuff right around the end of your barrel. If the mod isn’t removed after shooting, the gases will sit and eat into your muzzle where they are contained (let alone eat the moderator and barrel in general, not that I can comment on cleaning of personal sporting rifles). After shooting, take your moderator off and wipe your crown and muzzle as a very bare minimum. But here’s the bad bit – even if you do clean your rifle, you have to do it properly or you could risk damaging the crown. A little bit damned if you do, damned if you don’t, I know. By ‘properly’, I mean avoiding: going in dry with your phosphor bronze; yanking the phosphor bronze back into the bore; and using a scrubbing motion inside the bore (not so much crownrelated but just a no no).
Everyone will tell you different ways to clean a rifle, but as long as you avoid these things, and keep it wet with cleaning fluid from start to finish, and leave it very dry, you won’t go too far wrong.
Stainless vs carbon steel for barrels
Every shooter has their own idea of what a good looking rifle is, so is there any difference? Yes, there is. Before saying anything further, it should be known that ‘stainless’ doesn’t mean ‘100% guaranteed not to corrode’, and will likely pit and rot in the same way when abused.
As steel is an alloy, it is also worth saying that stainless barrels and carbon barrels from different manufacturers will have different ingredients and most barrel steel recipes mix their ingredients to lean towards strength over anything else. Generally, the two barrels are made from two different types of steel entirely and will therefore have different metallurgic properties. The vast majority of match-grade barrels on the market are made from stainless; the reason for this is that stainless is marginally softer, which lends itself to a slightly better internal finish – or an ability to finish it better more easily. Carbon barrels can be just as accurate, but it is somewhat harder to get them to the same finish quality. The finish on raw stainless obviously can’t wear off, whereas blueing can, but luckily Cerakote has solved this making the finish hard as nails.
At the end of the day, I would say barrel quality is more important. A badly made barrel made from any steel won’t shoot as well as a well-made barrel from either, as it’s simple as that.
Hunters might be happy with 2-3 MOA accuracy while target shooters will be far more demanding
A typical .308 will retain acceptable accuracy for many thousands of rounds
You need to take particular care of the crown of your rifle barrel to maintain accuracy.