[Bear70]

I just cleaned my AR-15 with the Dewey Chamber brush. The AR-15 expert at the gun store told me how to use it when attaching a drill and using it at low speed. My question is, is it possible with that brush (which is made specifically for cleaning the AR chamber) to go too far and ruin the throat of the barrel?

 

[Big Bore]

Not unless it is made of stainless steel or has a steel core, then the steel could scratch the barrel. If it is brass or bronze and has a bronze center core then no, no way it is going to hurt the barrel.
However, I have been cleaning ARs and everything else for many, many years and have yet to see a reason for a chamber brush nor have I ever had a problem with anything chambering related to a dirty chamber. Clean it well and there is no need for one IMO. One thing I would not do though, and that is ever take a brush and chuck it in a power drill. I can see no reason on earth for getting that aggressive with any kind of brush if the rifle has seen any sort of routine maintenance.

 

[gdcpony]

I would never have thought of the drill! WOW! Some one did that?

I agree with the above, except that I do clean my chamber quite often. I soak a mop for a .410 with slovent and just put it in and turn it a few times. Then another to dry it out. Shouldn't take too much to do.

 

[hailstone]

There are dire circumstances when it is necessary to chuck the bore brush in a drill. When it happens too you you'll then appreciate the knowledge that someone has done it before. Until then don't be judgemental!