Barrels 101

[bigbore]

Can you explain copper fouling to me like I'm 4 years old?

My 11.5" is a SS Wilson/RRA barrel that I cut down, plugged the gas port, and drilled another 1" forward. Its been host to a few different suppressors, been through 1 Hackathorn class, and lots of blasting with a fair amount of full auto mixed in. I just passed the 5K round mark a few weeks ago. To see how it was shooting I put up a target at 100yds, and put 5 75gr TAP rounds down range. 4 of those 5 shots can be covered with a nickel. It still shoots.

Its a well cared for barrel as far as carbines go. I clean it after every trip to the range. Hoppes #9, wet patch dry patch. I dont use a brush.

For the first time, I did the hoppes procedure, then shooters choice copper remover - wet patch dry patch. I lost count, but It took 45 minutes before the patches came out white instead of blue.

With this being an "economy" barrel (will foul more), which still shot damn well, with all that copper, how much of a concern is copper fouling in a practical carbine?

[K.L. Davis]

Can you explain copper fouling to me like I'm 4 years old?

I don't know if I can explain anything to anyone in those terms

Nor do I think that I can share anything about barrel fouling that you do not already know, but here is what I do know. Jacket fouling is a result of two things, the first being the jacket material that is released from the bullet in the initial stage of the shot, this occurs as the "gases" are actually in a plasma state and heat the jacket to the point that copper is released into the plama state.

This is a more like a plating really, it occurs in the very first part of the barrel throat and bore and is generally very uniform in deposition.

After this, the more traditional form of fouling occurs as the gilding metal galls in the bore; these patches of built up copper cause differences in the friction that is applied to the bullet as it travels down the bore. This friction can "tear" at the bullet's jacket and deform the base of the bullet, causing it to be unstable in flight.

Now, how often does it occur and at what point is it an issue? I have found that barrels are a lot like people in this matter; just like some people have a natural propensity to be artistic, athletic, or whatever... some barrels will foul more than others -- there is no hard and fast rule as to what make a barrel more or less likely to be a "fouler", but bore surface and consistant/correct bore diameter certainly play a big part in it.

As you know, there are the odd occasions where a barrel can not go a half dozen shots without throwing rounds all over the place... a good cleaning and it is back for a few more rounds, but fouls out just as quickly -- I think the name for these is "lemon" or "junk"?

And as you know, some rifles can go hundreds or thousands of rounds with little effect on accuracy from fouling -- when a shooter makes his first shot, it is called a Clean Cold Bore (CCB) shot, professional shooters even have seperate dope for this... oddly enough, the CCB shot is generally not the most "efficient" shot, as thin films of lubricants can increase the force needed to push that first shot and the cold bore is "tight" -- this CCB shot generally will have a higher recorded peak chamber pressure than the follow-up shot, I have known guys that even put a round in the ground before a patrol for a "fouling shot" (and other reasons).

As stated, bore surface is a primary suspect in a fouler... lapping and plating are thought to be preventive measures and record books support this.

To answer your question though, fouling is a concern if it is a problem (how is that for a cop out!) -- with most "practical" guns, fouling will reduce accuracy so little that it is not noticed... we can always blaim that one "flyer" on fouling though -- benchrest shooters can give themself ulcers worrying about it, but most of us don't have to worry that much, the potential for the group opening can still be covered by the illuminated dot in the optic sight...

As for the "blue patches" as a litmus test for copper... that can be very deceiving, it takes very little copper to make those patches blue and a lot of that fouling resides in the corners of the rifling, where is is doing little harm.

[SinnFéinM1911]

I wonder if I can make a barrel out of kryptonite ?? That way I can fight evil powers across the universe ....

All joking aside, GREAT POST KL, like always ...

[Airborne12b]

I know this is going to paint me as a noob, but I have to ask. I just built my first AR. This will not be my first time using the platform by any means, mind you. I have been isued probably 10-12 different AR variants over my time in the Army but none of these were NIB. The closest was the M4 that I was issued when I deployed to Iraq. As such I was never concerned with proper break in. For that matter I never remember in my time in the Army ever being told how to break in a new rifle. I am not sure if this is the best place to post this question but I figured that it being titles Barrels 101 that I would post it here. Thanks.

[Leethal]

Great stuff!

I know this is going to paint me as a noob, but I have to ask. I just built my first AR. This will not be my first time using the platform by any means, mind you. I have been isued probably 10-12 different AR variants over my time in the Army but none of these were NIB. The closest was the M4 that I was issued when I deployed to Iraq. As such I was never concerned with proper break in. For that matter I never remember in my time in the Army ever being told how to break in a new rifle. I am not sure if this is the best place to post this question but I figured that it being titles Barrels 101 that I would post it here. Thanks.

It's my understanding that with chrome-lined barrels, there's no "break-in" other than just shooting it.

You can find SS and unlined Chrome-Moly barrel break-in instructions on the web... there are several methods depending on the author. YMMV.

[Stik]

So from what I've read, Colt, LMT, CMT, BCM and the upper end (true mil-spec) manufacturers use 4150 and the more civilian recognized manufacturers like RRA, DPMS, Bushmaster, etc. use 4140? Just curious.

I figure most of the 1/9 twist barrels will be the 4140, but as I've stated in other posts, I'm a tech junkie and "just want to know". Also, alot of folks use "Wilson" (Wilson arms) heavy match barrels and E.R. Shaw "heavy match" barrels, I assume they are mostly 4140 when supplied to RRA, DPMS, Model 1, etc unless they are the 416 SS?????

Great post, very informative. Thanks for your time input into it.

[C4IGrant]

So from what I've read, Colt, LMT, CMT, BCM and the upper end (true mil-spec) manufacturers use 4150 and the more civilian recognized manufacturers like RRA, DPMS, Bushmaster, etc. use 4140? Just curious.

I figure most of the 1/9 twist barrels will be the 4140, but as I've stated in other posts, I'm a tech junkie and "just want to know". Also, alot of folks use "Wilson" (Wilson arms) heavy match barrels and E.R. Shaw "heavy match" barrels, I assume they are mostly 4140 when supplied to RRA, DPMS, Model 1, etc unless they are the 416 SS?????

Great post, very informative. Thanks for your time input into it.

BM uses 4150, just not the kind that the Military requires.



C4