CLEANING RIMFIRE BARRELS & ACTIONS
INTRODUCTION
WHY CLEAN A BARREL?
Here’s the bottom line first. Cleaning a target rifle won’t in itself increase your score on a target, but not cleaning will definitely lose you points by degradation of accuracy of the rifle & increased chance of malfunction.
WHAT IS ‘FOULING’?
Each round of rimfire ammunition fired leaves various kinds of fouling (crud!) in a rifle barrel. The fouling is composed of things like lead from the bullet; the residue of the waxy lubricant used on the bullet; residue of burned powder (including carbon fouling); granules of unburned powder & also gritty residue from the primer. Additionally, rimfire ammunition tends to leave traces of bullet lubricant & a smoky residue in the rifle action.
Although lead fouling is greatly reduced by the bullet lubricant, it will still occur & build up with successive shots fired, both in thickness & extent in the bore.
Lubricant residue is largely prevented from building up excessively in the bore by the passage of subsequent bullets but becomes more of a problem around the chamber where the lubricant can be scraped off when a bullet is fed into the chamber.
Burned powder fouling can build up over time, especially where it forms carbon deposits. The carbon fouling looks like a thin, black, but very hard layer which builds in the area immediately in front of the chamber & extending a short way down the bore. In bad cases it can build up to such a degree that it forms a ring which slightly constricts the bore, so a bullet passing through it can have its diameter marginally reduced, or at least its surface damaged. The carbon deposit build-up will be slow so its effect may be imperceptible until a sudden and otherwise inexplicable decline in accuracy occurs.
One type of fouling can encourage another type to build up – for instance powder fouling may build up faster on or around lead fouling than it would have done on a clean bore surface. Also fouling, whilst not itself corrosive, can attract moisture thus promoting rust or pitting in the bore.
There’s another type of bore fouling – essentially dust, grit, fibres from cleaning patches or anything else which happens to find its way into the bore – we’ll cover this type later.
Perhaps not properly termed fouling, the ultimate unwanted foreign body, in a barrel, is a stuck bullet. Be very aware of a shot sounding different to usual – there is a very remote chance of a ‘squib load,’ causing an underpowered bullet to not exit the barrel. If not carefully removed, the next shot will hit the stuck bullet, resulting in a ruinous barrel-bulge (in full-bore rifles, the barrel may rupture, and cause serious injury).
To properly discuss the disadvantages of bore fouling, a slight digression into basic rifle accuracy is needed.
The theory of rifle precision/accuracy is an almost endless subject but in the most basic sense shot to shot consistency is the key. Firstly, consistency in how a round of ammunition ‘fires’ & propels the bullet down the bore (i.e., ‘internal’ ballistics). Secondly, consistency in how the bullet flies to the target (i.e., ‘external’ ballistics). Consistent internal ballistics result in as little variance as possible in muzzle velocity which obviously is vital for consistent external ballistics. Additionally, each bullet needs to travel down the bore with as little deformation or damage as possible – bullet damage will result in the aerodynamic drag on the bullet being asymmetrical thus pushing the bullet away from the ideal path to a ‘10’ on the target. Damage can also unbalance the bullet – even a slight imbalance negatively influences a bullet spinning at 40,000 rpm.
The repeatable precision of high-quality ammunition which allows consistent internal ballistics is governed by maintaining many extremely small manufacturing tolerances such as relate to the dimensions of the cartridge case; the consistency of the brass thickness forming the case; the consistency in weight & effect of the priming compound & powder; the consistency of the bullet’s weight, shape, dimensions, and centre of gravity, plus consistency in the way the loaded round is assembled. If a single loaded round in a box differed from the others in any way which was outside of very tiny limits, that round could have sufficiently different internal ballistics, with the corresponding knock-on effect to external ballistics, to cause an increase in the group size & perhaps a dropped point.
Back to the disadvantages of bore fouling. Firstly, the degree of fouling varies – increasing as more shots are fired. This may affect how one bullet travels down the bore compared to another or even result in bullet damage; in any event it runs contrary to the ideal of totally consistent shot to shot conditions (for internal ballistics) – an uncontrolled variable has been introduced.
For consistency of bore condition, ideally every shot would be fired from a perfectly clean barrel – of course this isn’t practical, & in some shooting disciplines a course of fire of 60 shots plus sighters may have to be fired before any cleaning could be considered. With a well-maintained barrel this isn’t a problem – problems start to crop up when several full courses of fire have been shot without proper cleaning, by which time group sizes may have grown, points lost & the barrel will be much harder to clean.
Is ‘not cleaning’ ever a good idea? In the context of rimfire rifles we’ve all come across the shooter who claims to have been successful without any barrel cleaning, but lost accuracy when he (it normally is a ‘he’) eventually did clean it. If there’s any truth at all to these stories the reason is likely to be that the barrel was not thoroughly cleaned during this ‘once in a blue moon’ event – hardly surprising as a ‘never cleaned’ barrel takes far more effort to clean than can be imagined. The easily available bore scope stands witness to this. Perhaps the ‘cleaning’ did little more than disturb the fouling. Additionally, a partly/badly cleaned barrel may require quite a number of shots to settle down again.
Whilst it’s not uncommon for the first shot or two from a clean bore to have a slightly different point of impact, any properly cleaned barrel settles down after just a few shots during the normal sighter period. The negative issues related to infrequent, inadequate, or no cleaning, are far greater.
HOW TO CLEAN A BARREL
Ask four rifle shooters how to clean a barrel, and you will get six opinions & at least two of the shooters won’t ever speak to each other again. It can be that sort of subject.
Equipment:
A bore-guide to suit your rifle action. The bore guide helps to keep bore cleaning solvents out of the action area & as the name suggests it guides & centres the cleaning rod in the bore minimising the rod rubbing on the rifling near the chamber.
Cleaning Rod – there are many available, pick one with a rotating handle & which is long enough to reach to the muzzle without the handle clashing with the stock (the cheek-piece may have to be removed or lowered during cleaning). Make sure the rod is compatible with the cleaning brushes & jags etc which screw on the end (there are many different non-compatible systems).
Cleaning brushes, jags, patches etc – a spear-point type jag is simple to use but needs the correct size of cloth patches. Spear-point jags work well because the soiled patch automatically falls away as the rod is drawn back. The VFG system of dedicated jags & felt discs is another very convenient system & perhaps the easiest to use, although it’s good to have the standard jags & brushes as a backup. Brushes should be phosphor bronze, and some nylon ones.
Bore cleaning solvents – for rimfire the three main elements to remove from the bore are lead, carbon & other powder fouling. It’s preferable to use two types of cleaner – one which is a specific ‘carbon cleaner’ & one which is a more general purpose type which with remove powder & lead fouling. There are varying opinions about solvents. Ammonia-based fluids are best avoided as they can be harmful to barrels (especially stainless ones) if left in more than a few minutes – they also smell awful. Their advantage is they are very effective for copper-fouling removal, but that’s not a fouling issue with rimfire barrels. It’s fair to say that rimfire bench-rest shooters have to be fanatical about all aspects of equipment, especially cleaning, and a firm favourite amongst them is ‘Boretech Rimfire Blend,’ preferably preceded by a carbon remover.
Oil / lubricant – it’s good to have a light gun-oil for general use.
Cleaning rest or cradle. This sits on a bench or table & holds the rifle in a suitable position for cleaning. Once you have used one you won’t want to clean without it.
‘Pull-though’ cleaning kit. This is for a specific use (explained below) – it’s not used for actual cleaning.
Basic Cleaning Procedure.
The rifle bore should be thoroughly cleaned after competition, or extended practice. Bearing in mind clean means leaving nothing but air in the barrel, it’s not practically possible to ‘over-clean’ a barrel, but any cleaning needs to be carefully done.
So, with the bore guide in place, using the cleaning rod, push a cotton patch or VFG felt wad, wetted with cleaning fluid, from chamber to muzzle. This will remove loose debris and apply a coat of fluid to the barrel’s bore. We recommend this first application is with a carbon-remover cleaning fluid. Because carbon affects mainly just ahead of the chamber, you may wish to additionally use a short rod fitted with a mop, felt wad or brush to more liberally wet this area.
Leave it a few minutes to attack the fouling then push another couple of wet patches or felts through the bore. If they are still dirty repeat the process & follow up with a few dry patches. If the barrel has been neglected, it may take repeated cleanings to remove carbon.
Next, run through a patch or wad, wet with the general bore cleaner, and leave this to work for a few minutes, before passing-through clean patches or wads.
When the patches emerge looking free of fouling, it may be that the job is done; but the test is to repeat and see if more gets removed.
Do not pull a patch or wad back through the barrel – discard it as it emerges from the muzzle; this avoids rubbing debris, especially carbon, backwards and forwards in the barrel, as that could act as an abrasive.
If the cleaning patch feels slack when pushed through the barrel, it’s too small. If too tight to enter the bore, then it is too big, so, either obtain smaller patches, or offset the patch on the jag – trial and error will soon show the correct size and where to ‘spear’ it on the jag. If you prefer the type of jag around which the patch is wrapped, then again, trial and error will determine the correct size of patch. Do not try to force a very tight patch/jag – it may become stuck for life (I’ve done it). Always use the correct size of jag.
Do not imagine that eyeballing through the barrel will indicate its condition. The only true check is with a borescope – and there are now cheap but very effective ones, as well as expensive and even better ones; but the budget models are more than good enough.
A regularly cleaned barrel is much easier to deal with & each cleaning session will be quite short.
Even if the bore seems perfectly dry, there may still be minute traces of solvent in the ‘grain’ of the surface of the steel, so it may take a few shots to burn-away any trace of cleaning fluid before the shots completely settle.
If shooting is over for the day or weekend it’s a good idea to push a patch or felt wad moistened with the light oil – this will protect the bore from moisture in the atmosphere while out of service. Before shooting again, remove all traces of the oil with a patch or wad moistened with a solvent such as Lighter Fluid or White Spirits etc – push a few dry patches through the bore to remove any of this solvent which hasn’t already evaporated. Failure to completely remove oil before use will, at least, cause inconsistent accuracy for several shots; at worst it could wreck the barrel, as an appreciable amount of oil behaves like a partial blockage in the barrel.
Firing a shot when there’s part of a cleaning patch or felt wad accidentally left in the bore following cleaning, could have a catastrophic effect – so always check the barrel is clear before use.
Additional Cleaning Procedures
Some shooters also scrub the bore with nylon or bronze-bristled brushes, wet with a bore cleaner. Bronze brushes have the advantage of scratching the fouling to assist the work of the cleaner & clearing away the debris. The bristles are much softer than barrel-steel, so do no harm – but, they may have the effect of scrubbing bits of hard carbon up and down the barrel; so very-best practice is to pass brushes only one way & then unscrew them as they exit the muzzle.
Action Cleaning
Aside from any specific maintenance procedures, which the maker of the rifle action may advise – when cleaning the bore, it’s a very good idea to clean around the chamber end of the barrel, as bullet lubricant can accumulate there along with powder residue. The combination of lubricant & powder residue can result in the action not closing properly, or the case extractor not working. Rifles used on outdoor ranges also run the risk of dust or grit being embedded in this sticky combination of fouling. ‘Q-Tips’ moistened in a bore cleaner or white spirit can be used to clean this area. Don’t forget the face of the bolt either.
This is a good time to check other things such as the function of the trigger (has some adjustment changed?). Check the sights are still securely fixed. Check the bedding bolts are tightened properly with the use of a torque wrench. Check any stock furniture is secure.
Use of the ‘Pull-through’
When rifles are used out of doors & especially in very active disciplines such as Biathlon there’s a risk of all sorts of debris or water getting into the bore, even with the use of a muzzle cover. It’s good to have a ‘pull-through’ kit on hand for emergency use; not to clean the barrel, but merely to remove obstructions. Additionally, if shooting outdoors it’s good practice to use the ‘pull-through’ before & after any stage of competition – just to ensure the bore is free of dust, grit, or unburnt powder granules etc. ‘Pull-throughs’ should be pulled from chamber to muzzle, with the pull cord aligned straight down the barrel – don’t let the cord rub along the crown. The crown is probably the most important part of the barrel, and the slightest imperfection will cause escaping high-pressure gasses to upset the bullet.
The rope-type of pull through, usually incorporating bronze bristles, come with caveats, so is best avoided.
Finally – there are some excellent You Tube videos on cleaning, some specific to biathlon & other rimfire rifles.
If in any doubt regarding any aspect of cleaning – please contact the writer.
Brian Fox
