The interesting thing about an extreme long-range rifle like a CheyTac M200 Intervention is that breaking it in requires the influence of sending a few bullets downrange.
The pressure will smooth out some of the aberrations inside the bore, smoothing over machining marks and other irregularities that adversely affect accuracy.
This is why most ELR rifles are most accurate after they’ve been through 50 or 100 rounds or so.
The reason this is interesting is that there is a double edge here; each bullet you send downrange will also leave copper fouling in the bore. There is a delicate middle ground where the rifle will perform best, but after a certain point, leaving the bore too heavily fouled will adversely affect accuracy.
Here’s what you should know about copper fouling and accuracy, and how you can remove it.
Copper Fouling and Accuracy
When you remove the bolt from your ELR rifle and shine a bore light down the bore, all those black streaks and spots you can see are (mostly) powder fouling.
Powder fouling can, under certain circumstances, hinder feeding and extraction, and in some cases can accelerate corrosion, but it’s also easy to remove with a bore cleaner, a brush and some patches.
It’s what you can’t see easily, copper fouling, that is the true noxious influence. Copper fouling occurs when infinitesimally small amounts of copper are shorn off each bullet as it passes through the bore. After a while, this copper gums up the rifling and inside of the barrel.
Over time, copper fouling will ever so slightly change the bore dimensions and can adversely affect the efficiency with which the rifling engages the bullet.
In most rifles, this hardly becomes an issue, especially at intermediate ranges, but in a rifle like the M200 Intervention, which shoots sub-MOA and has an effective range greater than a mile, a dirty rifle, excessively copper fouled, may start to produce slightly more open groups.
So let’s talk about how you can identify it and get rid of it.
How to Identify Copper Fouling
First, don’t jump the gun (no pun intended) and assume that, if your rifle isn’t producing the groups you want, the issue is fouling. Individual guns foul up at different rates and some will exhibit inconsistencies readily whereas others will not.
All the same, if you suspect copper fouling is taking a toll on your accuracy, get a borescope and take a look in the bore, starting at the throat of the chamber.
Fresh fouling will appear like bright copper, but mostly, copper fouling is going to appear blue-green, as streaks along the chamber throat. Pass further into the barrel and you should see the same blue-green streaks in the bore further away from the chamber.
That’s the stuff you need to clean out of your bore to maintain a high degree of accuracy with your M200 Intervention rifle.
Getting Rid of It
Now let’s talk about what you can do to get rid of the copper fouling inside your M200 Intervention’s bore.
First, regular powder fouling isn’t going to get rid of it. The reason it’s important to note this is because you can clean out all the powder fouling from a bore, check it with a bore light, and it’ll look shiny like a mirror and perfectly clean. There could still be copper fouling in there, though.
To get rid of copper fouling you will need a bore cleaner that is expressly rated to dissolve it so it can be removed. You will also need a bore brush of appropriate caliber along with a clean jag and patches.
Remove the bolt from your CheyTac M200 Intervention rifle. Attach a patch soaked with the copper fouling solvent and run it through the bore, from chamber to muzzle.
Remove the patch and jag and apply the bore brush; push this through from chamber to muzzle to abrade and dislodge the copper fouling in the bore.
Now switch back to the cleaning jag and patches and run dry patches through. The first few should come out blue-green with fouling, but that should diminish as you remove it.
Replace each fouled patch with a clean one and repeat till they come out clean, then apply more copper fouling solvent and repeat the whole process over until your patches come out white.
When you’re done, check the bore with your scope one more time to ensure that all traces of copper fouling have been removed from the chamber throat and rifling.
Explore CheyTac M200 Intervention Rifles
Hopefully you found this article helpful; it should show you from a high level how to remove the copper fouling from the bore and, once done, your rifle should be shooting as accurately as when you first broke it in.
If you’re here for a new ELR rifle, check out our collection of CheyTac M200 Intervention and other precision rifle platforms, and get in touch with us if you have any questions.
