Predicting Barrel Wear, Part Two

We’ll start with pitting and cleaning rod damage. In the decade plus that I was the armorer for the Army Reserve Shooting Team I replaced about as many barrels that were damaged by rough or improper cleaning or pitted due to neglect on the part of the shooter as barrels that were genuinely worn out. I replaced a lot of pitted barrels. Some folks are under the impression that they can "bullet proof" themselves from pitting by substituting stainless barrels in place of chrome molly barrels.

Granted, stainless is more corrosion resistant than carbon steel but stainless is not corrosion proof. I have seen many stainless barrels ruined by pitting. Pitting results when corroded barrels are not attended to for a prolonged period. Corrosion often results when the owner fails to clean his bore after a shooting session and the problem will be exacerbated if such a firearm is stored in a moist environment even for a short period of time.

If you store your firearms in a gun safe make sure it has a good dehumidifying rod. Small amounts of pitting are sometimes not fatal in most sections of the bore. The exception is the muzzle and crown area where even minimal pitting will usually ruin the barrel. Avoiding Pitting The first step to avoid pitting is to thoroughly clean your firearm every time you shoot it and never get complacent and put away a dirty gun.

After I have removed every last trace of bore fouling I clean the chamber with the appropriate chamber brush and a high pressure aerosol gun scrubber spray. Follow up with a patch wet with Windex without ammonia. Most common Windex contains ammonia but they also make it without ammonia and that is the one to use. The container of non-ammonia Windex I have is marked "Crystal Rain" and this flushes out the ammonia from cleaning solvents. I mentioned that a lot of bore pitting occurs at the muzzle.

I believe that may happen due to not getting all the gunk and excess solvent removed. Pre-ban guns with flash suppressors may exacerbate the problem as they tend to hold these substances. On guns with flash suppressors use the aerosol Gun Scrubber or its equivalent to spray the front of the muzzle clean as well as the inside of the suppressor and the flutes. You can use a clean shop rag or cotton swab to remove the excess moisture at the muzzle and insides of the flash suppressor.

Dry out the bore with about four clean patches. If you are going to shoot the next day you’re all done at this point, with the exception of cleaning and lubing the bolt carrier assembly and cleaning the upper receiver where the carrier lives. On the other hand, if you are going to store the gun for more than a handful of days, especially in a moist environment, you need to use some kind of rust preventative.

Brownells did a super comparison of various common rust preventatives a few years back, Gun Cleaning Clinic: Knowing the Limits of Rust Preventatives by Steve Schmidt (goo.gl/a4j VAx) In the center is Windex WITHOUT ammonia. A couple of products gave really stellar results. They were Boeshield T-9 Waterproof Lube made by Boeing and good old WD-40. Apply these to the bore using a loop tip, very saturated with the product of your choice.

I work the patch back and forth several times to burnish the preventative into the pores of the bore. Then I allow the patch to exit at the muzzle and I pull it back gently into contact with the crown and muzzle. Holding the rod at the back by the shaft, not the handle, I rotate the patch in several 360 degree turns while applying rearward pressure so the muzzle and crown get a good coating.

Some of you are probably jumping up and down right about now saying that a patch should never be pulled back through the bore after exiting the muzzle. That applies to dirty patches. We just finished cleaning the bore so this patch won’t be dirty. Additionally, we are not pulling it back through, just applying rearward pressure. Some sprays of either rust preventative up through the flash suppressor impacting the muzzle and crown won’t hurt.

Likewise, a shot in the chamber is good as I see a lot of rust form there and that can cause feeding and extraction issues if it gets bad enough.

Because we are applying these preservatives liberally, store the gun muzzle down for at least a few days to avoid having preventative pool in the action and on down into the buffer area, trigger, or lower receiver. We need to remove these substances before shooting to avoid pressure spikes and first shot fliers. To do so, just hit the chamber with a little shot of Gun Scrubber, patch the bore out with nonammonia Windex, and follow with dry patches.

If needed, hit the flash suppressor and muzzle with a splash of aerosol Gun Scrubber to remove any excess in these areas. Salt Bath Nitriding Another very effective method I employ to avoid pitting is having my barrels salt bath nitrided. The trade names for this are Isonite or Melonite and there are several locations around the country performing the service. The nitriding compounds are applied both to the inside and the outside of gun barrels.

This is different than bluing which only goes on the outside and provides no protection to the important and rust-prone bore. The nitriding procedure can be performed to either barrel steel but you will have to identify which you are sending as the processing is a little different. Because of the near 1,000 degree heat involved in the nitriding, barrel extensions will want to come off. This ain’t cool!

If you build a gun for a customer only for him to return it a few weeks later because the barrel is unscrewing plumb out of the extension, you lose credibility and the customer loses the service of the rifle while you fix it. I covered several ways to deal with this in the September 2013 issue called "Retention Of AR-15 Barrel Extensions." I suggest you follow the advice in that write up. Nitriding is not an end all, do all.

It is just added insurance and isn’t meant to take the place of proper and prompt cleaning after each range session and the use of a rust preventative if you are going to store the gun for more than a few days before your next range session. Likewise, you need to continue to store all firearms in dry conditions (use a dehumidifying rod in a safe) whether nitrided or not. In addition to helping curb rust there is one more benefit of nitriding that I really like.

It makes the gun very easy to clean which lessens the probability of cleaning rod damage. I hear a lot of claims right now that nitrided barrels wear longer. Maybe they do but currently I don’t have near enough data to substantiate or refute those claims. You saw that laundry list of barrel characteristics that can lengthen or shorten barrel life earlier in the article.

Until such time as someone (or myself) sets up a scientific study where 20 barrels are purchased all from the same maker and all with the same internal specifications and half are coated and half are not and then compared for wear I don’t think anybody can make any statistically valid claims one way or the other. Damage During Cleaning I have mentioned before that the lands only stick up above the grooves by about the thickness of a sheet of paper. They are very easily damaged.

You can avoid damage and increase the life of your valuable barrel by following these suggestions. First, always use a quality, straight, one-piece cleaning rod with a freely rotating handle and wipe it off frequently to keep it clean. Use a rod of the proper length for the barrel you are cleaning. I have a longer rod for cleaning 26" match rifle barrels than the one I use for 20" barrels.

Using the longer rod inappropriately in the shorter barrel results in too much rod flex which is one of the big damaging culprits. Use a rod of the correct diameter. Don’t try cleaning a M1A .30 caliber rifle with a .22 rod. Skinnier rods flex more! Second, I like to have two rods for each type of gun. I have one rod with a female thread on the end that I use exclusively with screw-in bore brushes and a second, dedicated rod for use with bore patches.

Before I screw the tip for that rod on for the first time I bevel the 90 degree shoulders that usually exist just forward of where they attach to the rod. Then I use blue Loctite on the threads of the tip where it screws into the rod and I tighten it on to prevent the tip from unscrewing during cleaning. I have seen so many guys push a patch down through the bore and then remove it from the tip at the muzzle as they should. Then they get in a great big hurry and yank the rod back up.

If the tip has come loose, as they will if you don’t Loctite them in place, gravity will cause that loose tip to slope down after it exits the muzzle. A hard fast rearward yank on the rod can ram the back of that tip right into the bottom of the crown and booger it big time. Ensuring that the shoulder of the tip is beveled combined with keeping the tip in alignment with the rod via Loctite holding it in place and not jerking the rod so much should help eliminate the problem. Third, don’t mix bore solvents!

You can end up creating a third compound that can damage your bore. I’m not using the term "mix solvents" like one might imagine a kid with a chemistry set pouring one bottle into another. I am thinking of using regular Shooter’s Choice in your brush to get the carbon fouling out and then following that with Sweet’s 7.62 on a patch to get the copper. Bad idea!

It’s perfectly fine to use regular Hoppe’s No. 9 on the bore brush to get the carbon and then follow with Hoppe’s Bench Rest to attack the copper because they are both from the same company and compatible. Same, using regular Shooter’s Choice on the brush and following with Shooter’s Choice Copper Remover on the patch. Follow solvent manufacturer’s instructions.

Hoppe’s says it is OK to leave Bench Rest in over night whereas the maker of Montana X-Treme 50 BMG says 15 minutes is the time limit to soak a bore with their product. Big difference! Don’t use high ammonia solvents like Sweet’s and the Montana X-Treme with bronze bore brushes as bronze

contains copper. The harsh solvents will eat your brush for lunch and can easily deposit copper in the bore from the brush, making your cleaning job more difficult. Forth, use quality bore brushes with windings that never terminate on the front of the brush, unlike the cheap ones. The slightest flex or bend in the cheap ones will jam those sharp open windings right into the barrel, causing damage. Always use a clean brush.

I throw my dirty ones in the solvent tank of my ultrasonic unit when I am cleaning regular gun parts. Other people spray them clean with an aerosol gun scrubber, or use lighter fluid to hose out the crud. Just allow them to dry before their next use and replace them when they get worn down or bent to the point where they can’t be straightened. I don’t have much faith in nylon bore brushes because I don’t think they are abrasive enough to attack the hard, baked-on carbon fouling.

You can use them with high ammonia solvents, however, unlike bronze brushes which shouldn’t be used with such solvents. Never try to reverse the direction of a brush when it is inside the bore. This can cause a lot of dangerous rod flex. Fifth, a word about abrasive cleaners. I don’t worry about abrasives, such as J-B Bore Cleaning Compound. They actually do a great job of removing stubborn fouling that solvents alone may not get. I do worry about how they are used.

Normally they are applied to a patch and then worked back and forth in a scrubbing action in the bore. A lot of guys push the patch forward and stop it just before it exits at the muzzle and then pull it back down to the chamber and repeat a bunch of times. On the forward stroke, if you mess up and push too far and the patch exits the muzzle, remove it and don’t pull that filthy thing back through the crown. J-B can also be "short stroked" in problem areas where fouling tends to be heavy and persistent.

For example, if the gas port isn’t properly broken in when the gun is new, the port and about two or three inches forward of it may be such an area. The throat is another such area. Use of abrasives there gets the fouling out but the short stroking action may cause damaging rod flex. Let’s take the gas port area as an example of using short strokes of about three inches each.

The patch is initially pushed a couple inches forward of the port, then the direction of travel is reversed and the patch is pulled back to about one inch behind the gas port. Even though you are reversing the direction of the patch you are not going to get much rod flex when pulling it, however, the next patch reversal will be at that stopping point one inch behind the port when you go from pulling back to pushing. That is where you will get the rod flex.

J-B has a creamy texture and you probably won’t feel much flex at all but it will occur. A lot of that flex will happen at the back of the barrel just forward of the chamber and it can easily damage the lands, but you won’t feel a thing! So, slow down your stroke and be particularly careful scrubbing with abrasives and changing direction from pulling to pushing inside the bore. Last, but certainly not least, is a quality metal bore guide.

I’ve seen incidents where a worn plastic bore guide ruined a brand new barrel. The bore guide in question began life as a .22 caliber AR bore guide and no doubt performed its job just fine when new. Unfortunately, the hole that the rod goes through wore fatter with age. When I inspected the offending unit for a customer at Camp Perry, the guide had grown clear to .35 caliber!

That bore guide my customer was relying on to keep the rod going straight and with minimal flex was doing the exact opposite and a perfectly good, very expensive barrel was destroyed as a consequence, yet the shooter never felt anything untoward. So my advice is to use nothing but quality metal bore guides made by the likes of JP Enterprises or Wheeler Engineering.

Diagnostics How do you know when a barrel is shot out? "An early indication from the USAMU was that they had gotten in the vicinity of 7,000 rounds from a barrel before a rifle wouldn’t clean at 600. … Well known builder Derrick Martin doesn’t even recommend checking an AR barrel until it’s had 5,000 through it." That’s the advice given in The Competitive AR15 by Glen Zediker. Barrels normally decline gradually and not all at once.

Most bad scores or bad shots are caused by shooter error or inferior ammo, not worn out barrels. You know when a barrel is shot out by its shooting performance and no other way. Yes, you can take throat gauge readings and a reading of five or more tick marks may tell you that it is time to test the gun for group. You can also take Stoney Point readings and any bullet jump exceeding ¼" might also suggest test firing.

You can bore scope for heavy and deep fire cracking, roughness in the back three inches or more of barrel, and/or pitting anywhere, especially up around the muzzle. If one land is wearing down back at the throat that certainly points to problems. If you are seeing much fouling of either kind I suggest the shooter do a better job cleaning, or I just properly clean it myself, and that he then try shooting it again.

A lot of folks are fixated on the copper portion of fouling and tend to discount the black carbon fouling. Carbon fouling is debilitating to accuracy too and requires abrasives, such as a bore brush, to get out. Knowing the right questions to ask the shooter is very important in diagnosis. The first thing to find out is what classification is he? Marksman through Expert-class shooters tend to blame all bad shots on either the gun or the ammo, rarely on themselves.

Masters and High Masters normally shoulder the blame on themselves for not applying the fundamentals rigor-

The black plastic one at the right is worn out and close to .35 caliber. The owner ruined anew barrel because of it! ously enough. I have seen a bunch of them miss some rather obvious gun problems because they just don’t think to look there. Does the shooter think the gun is shooting fatter groups or is it still shooting good groups but with occasional unexplained fliers? A lot of fliers are not barrel related. Ammo (especially concentricity issues) is mostly to blame.

Gas tube alignment is another prime culprit in AR-15s. Has he changed something recently? Changing ammo lots or loads can cause a lot of problems that might be misdiagnosed as barrel related. If he is a person who normally spun his ammo for concentricity, but just didn’t have the time to do so about the same time as fliers and fat groups started? Swapping in anew magazine (even if it feeds well) can cause significant shifts in point of impact.

Pistol shooters were first to notice the relationship of point of impact to magazines used and sometimes machine rest test with their magazines to be sure none of them caused zero shifts. Also, look for copper build up on the feed ramps of the barrel, which might indicate that a magazine is not feeding straight. If the gun is used in National Match competition, is it performing poorly at only the 300 yard line, just the 600, or both?

Too many shooters (and gun plumbers) base a gun’s performance only on 600 yard performance. Typically, long range ammo has bullets seated out further to be single loaded and not fed from a magazine. Therefore, those bullets jump less distance than magazine-fed ammo like we use at 200 and 300 yards. Because of the longer bullet jump from ammo that is seated to magazine length, a barrel may be shot out with regard to 300 yard performance but still shooting strong at 600 yards.

If the shooter keeps an accurate round count log, how many rounds is he showing through the barrel? Anything in excess of 5,000 should probably merit a range test. Right before I test fire a customer’s rifle I check for obvious mechanical problems. Gas tubes out of alignment are notorious for causing fliers and fat groups. When I was armorer for the Army Reserve I used to find many loose butt stocks and sometimes loose buffer tubes causing the same problems.

It is like putting the stock in a different position in the shoulder for each shot and the best barrel in the world won’t shoot well under those circumstances. And for crying out loud, always check sight track- Shooters and gunsmiths can misinterpret this as barrel accuracy issues. ing. Dead spots and jumps can open up groups (especially at 600 yards where you are doing a lot of clicking) something awful. I also make sure that the bolt carrier is clean and properly lubed.

Otherwise, you will not get consistent lockups and optimal performance out of any barrel. When I test fire the gun I like for the customer to provide samples of his ammo. I gauge his ammo for concentricity to get an idea of the overall quality. I also like to run a chronograph on his ammo to see what velocity spread it clocks at. In addition, I like to fire with known-good ammo of my own which you can bet I have spun for concentricity.

When the smoke from the test firing clears, if his gun is shooting 10 shot groups exceeding MOA with his ammo and sub-minute with mine I show him the test targets and try to steer a conversation to how he loads his ammo. If both his ammo and mine shoot 10 shot groups over minute of angle I suggest rebarreling. My company motto is, "My goal is to help you achieve your goals." At the end of the day the customer is always right and if he wants anew barrel that is what he gets. AG