Thought I would give a heads up to everyone regarding the new Otis carbon scraper tool I got recently. I wasn't able to find much on it yet.  I had been wanting a cat m4 for awhile now but didnt feel like spending the $30 on such a simple tool. Saw Otis's new tool at a local gun shop for $20 and decided to give it a whirl. It's awesome.
I haven't tried the cat so I can't compare but the Otis bone has the same cleaning apparatuses aside from the patch holder and hex wrench. It does however have a threaded hole in the center so it can be used as a t handle on a cleaning rod. Can't say ill be using that feature much but hey it's only $20 and I have patch holders and hex wrenches galore.
    Now I am pretty anal about the cleaning of my bcg but I left a leave a bit of carbon on the bolt tail and inside back of the carrier. But damn I did t realize how much. That tool chewed massive chunks of carbon out of the rear wall of the "clean" carrier. After the rifle was shot next for about 350 rnds I used it again and it worked wonderfully. It has a knurled surface that gives good purchase to ream the carbon out of the carrier and the other scrapers work equally as well. It's likely heavier than a cat tool and if it was destined to be kept in my grip or stock I would likely go for the cat. However if yours is destined to sit in your cleaning box/ bench, I'd say its a good way to get the same job done and save $10. Take care!

Thanks for the review.  I have an Otis MSR/AR kit coming in the mail that has that tool included.  Can't wait to try it out.

Thanks!  I need something good and reasonable.

I did a review of it: OTIS BONE Review

Bought mine from Amazon and was amazed at how much carbon this little thing was able to scrape out of my "clean" bolt carriers.  For comparison, I have ("had") a brownells bolt carrier scraper with a screwdriver handle that was good at getting the big stuff out, but still needed detailed cleaning to get the rest.

Why do people think it necessary to scrape every last bit of carbon accumulation off of the bolt and related parts?

Why is there always someone who says, "Why do people think it necessary to scrape every last bit of carbon accumulation off of the bolt and related parts?"

Some people like "clean" whether it matters or not.  It's their rifle, it's their business.

I was less than impressed with it when I tried mine on the inside of the carrier. Have not use the other functions yet.

I'll second that statement.  I've not found one of my bolt carriers that has enough build up for the bone tool to even remove anything from any of the surfaces that it is designed to clean.  I haven't tried it as a t-handle for a cleaning rod yet, maybe that is where it will shine.

 

IMO a lot of it comes from the military. And the military gets it from using corrosive ammo for so long. When I first got out I was the same way, but over time have learned how clean it has to be to function 100%, and in fact more wear and tear comes from over cleaning than shooting.

It isn't necessary to get the bolt surgically clean.  It doesn't hurt to wait until the black stuff annoys the owner.

If I decide to clean the bolt
I go to the local hardware store, get a couple of $2 two inch brass wire wheels, chuck it in the drill and all the carbon is off in a minute or two.

Clean the inside of the carrier?  You're kidding.  Right?

Remember, it's a battle rifle.  It doesn't need to be cleaned within an inch of it's life.

I just purchased a Bone tool from Otis last week. One of my AR's was failing to go into battery due to excess carbon build up in the carrier. I used the Bone tool to remove the excess carbon to get the rifle back in operation with just a few quick twist of the tool.
It appears to be made of carbon steel not sure of hardness. I just removed the crusted up carbon in the carrier and was not trying to get it spotless cause I'm gonna shot it (a lot) anyway.
If you gotta have the carrier spotless soak it in some Kroil and use a bore brush that fits the carrier to remove the remaining carbon out.

Those of you who don't know why carbon needs to be scraped out apparently don't shoot your AR much or don't shoot one suppressed.  YMMV according to powder type etc.

I say it's GTG, Old Marine approved.

Old Marine  
(playing with black rifles since 1982)

Does doing mag dumps or using wolf ammo create more carbon? how about a can?

I shoot a fair amount without much of the above and never saw large amounts of carbon building up

I shoot a lot and a lot suppressed, and at no point have ever scraped carbon.  As long as you keep it lubed it shouldn't be a problem.

I thought filthy 14# settled this.

I'll admit after 31 years of shooting the AR-15/M-16 platform it was the first time this particular malfunction has happened due to excess carbon in the carrier.  A bad batch of powder I had which produced a lot of smoke and fouling may have been the culprit.
While on active duty as an instructor and competitor I never saw this happen especially with the hotter 5.56 loads.  
Anywho, If you need to remove an excess amount of carbon the BONE tool is an inexpensive tool to have in your range bag or on your gun bench.  (or just drop it in a bottle of Kroil for a couple of days)

I just keep the parts well lubed and have no issues with carbon on the bolt or anything else.Before,during and after I put a few drops of CLP in the carrier vents and work the action a couple times.This keeps the carbon on the bolt tail and in the carrier soft.Otherwise the carbon is self limiting.
If I do a high round count with cheap steel cased ammo or similar and have large amounts of carbon/funk I'll soak the bolt...dropped in tail end first...either in a jar of Hoppe's No.9 or CLP overnight,what doesn't fall off the bolt while soaking wipes right off.
But Im all about cleaning tools and an Otis fan,so I understand if folks like the bolt cleaning tools if thats what they want.In fact I have a B.O.N.E. in one of my Otis kits,haven't used it yet though.The bolt tools are not needed if maintenance,and more importantly if the rifle is adequately lubricated before,during and after use no matter how well you clean.