The .338 Lapua cartridge around which the McMillan TAC-338 is built generates pretty intense chamber pressure – around 60,000 PSI.
You know what this means: fouling, and plenty of it. Probably a lot of copper fouling, too.
That means you need to keep your McMillan rifle clean. Here’s why, along with a high-level primer on how to do it.
The Importance of a Clean Rifle
Extreme powder fouling in an autoloading rifle can gum up the gas port or create spacing issues around the bolt that both result in cycling or feeding issues.
The McMillan TAC-338 is a bolt-action rifle, so these things need not apply. However, copper fouling is what we’re looking at and it presents a unique issue: accuracy.
If you ever get the chance, scope a badly fouled bore and look for bluish-green streaks. This is copper fouling, left behind by the copper jackets of bullets, and then oxidized in place.
These copper deposits, however minimal each individual instance may be, slightly change the dimensions of the bore, and over time, they can accrue and impact performance, specifically accuracy, considerably.
Chiefly, these changes to bore dimensions can adversely affect accuracy, which is like, the seminal thing we’re talking about with a rifle like this that’s designed for extreme long-range shooting.
So, the long and short of it is you need to keep your rifle – specifically the barrel – clean.
The Basic Procedure
For the purposes of this high-level overview, we’re not going to look at cleaning the bolt or the trigger assembly, just the chamber and bore, since these are the areas that will impact accuracy when they are badly fouled.
To do so, remove the bolt from the receiver and set aside somewhere clean and dry. Then get yourself a cleaning rod with a brush and some jags of appropriate diameter, along with some bore solvent.
For this, you will need a bore solvent that is specifically rated for the removal of copper fouling. Standard fouling solvent might not do it.
To get started, run the cleaning rod, with a bronze cleaning brush attached, through the barrel a few times, from chamber to muzzle, just to scuff up the fouling in the bore.
Then, soak the brush in copper fouling solvent and work it through the barrel from chamber to muzzle.
Run it through a few times, then swap the brush for a cleaning jag and thread a patch through it. Run it through from chamber to muzzle, and you should see that the patch comes out faintly blue – that’s the copper fouling.
Repeat this process until the patches come out clean. If they don’t re-work the bore with a bronze brush, then run fresh patches through till they come out white.
It could take a while, as copper fouling is notoriously stubborn. With that said, once you’re done, and you’re sure the bore is clean and dry, get a bore light and check it out.
The bore should be clean and shiny, almost like a mirror, except for the rifling. This includes the chamber throat, which shouldn’t look matte black (if it does, there’s fouling there, and it needs to be cleaned).
Once your rifle is clean, make sure it’s completely dry and you can re-install the bolt.
Get Yourself a New Rifle
Here not to learn how to clean a McMillan TAC-338, but to find out where you can get one. The place to get extreme long-range rifles is B&B Firearms. Not only do they carry popular models from CheyTac, McMillan, and Armalite; they offer interest-free payment plans. For more information visit their website or get in touch with them directly at 484-616-0403.
