AR15: How bad is my crown?

[sloughfoot]

wait. I thought the AR15/M16 was designed to shoot bullets that tumbled. better for shreading thine enemy to tiny bits and all that. sounds like it's working perfectly.

If that's not the case, it will bring into question every piece of knowledge I learned while hanging out at the gun shop.

-rvb

Exterior ballistics=tumbling bad

Terminal ballistiscs=Tumbling good.

 

[churchmouse]

I see no evidence of lands or grooves in any of the pictures. Might give it a real good cleaning and take a look. (not a bore snake, sorry no fan)

Then take a look at this. Don't know about everyone else, I was astounded. Long read, scroll down to barrel wear.

http://www.luckygunner.com/labs/brass-vs-steel-cased-ammo/#reliable

That just verify my belief that cheap ammo is harmful.

 

[1911ly]

That just verify my belief that cheap ammo is harmful.

But I have learned on ingo that you never need to clean an AR. And if you can't shoot the cheap stuff your AR is junk

 

[churchmouse]

But I have learned on ingo that you never need to clean an AR. And if you can't shoot the cheap stuff your AR is junk

If you build up/buy a nice Hot Rod would you run gas and oil in it cause you are a cheap A$$...................................To me running steel ammo in my expensive gun is not saving me anything in the life of that gun......JMHO of course and I am sure some one who knows "More" than I do on the subject will chime in.

.................

 

[churchmouse]

But I have learned on ingo that you never need to clean an AR. And if you can't shoot the cheap stuff your AR is junk

I am not sure how many ingo folks have taken an EDM to an AR barrel...............

 

[1911ly]

If you build up/buy a nice Hot Rod would you run gas and oil in it cause you are a cheap A$$...................................To me running steel ammo in my expensive gun is not saving me anything in the life of that gun......JMHO of course and I am sure some one who knows "More" than I do on the subject will chime in.

.................

I tried the cheap stuff. I got tired of beating the cases out of the chamber. Wasting good range time. Not to meanting the damage I was doing to the gun. Not worth it. And I a little every time I hear I haven't cleaned my AR ever. Like it's a good thing.

 

[indyjohn]

Yeah, I need to get me some JB Paste. A couple of my Minute Of Angle guns aren't so much.

 

[1911ly]

I also don't get why I am chastised for chucking up a brass brush in a drill to clean the crud at the end of a barrel. But it's better to chuck up a brass screw and go at it? That seems more likely to be overly aggressive. But to each his own. And someone always has a better way then me any how

 

[churchmouse]

I tried the cheap stuff. I got tired of beating the cases out of the chamber. Wasting good range time. Not to meanting the damage I was doing to the gun. Not worth it. And I a little every time I hear I haven't cleaned my AR ever. Like it's a good thing.

Every time I read/hear this that person goes on my "I will never buy from or let them shoot my guns" List.

 

[churchmouse]

I also don't get why I am chastised for chucking up a brass brush in a drill to clean the crud at the end of a barrel. But it's better to chuck up a brass screw and go at it? That seems more likely to be overly aggressive. But to each his own. And someone always has a better way then me any how

Use the brass brush.

 

[1911ly]

Every time I read/hear this that person goes on my "I will never buy from or let them shoot my guns" List.

Use the brass brush.

We think a lot a like! Plus you rock 1911's so your a good guy in my books!

 

[Cameramonkey]

A drill and a bore brush, bad. maybe one of these with a sawsall and a slightly undersized bore brush? After all, its reciprocating so its not going against the lands and grooves... So its ok, right?

(Beware, some of the "also bought" items might be offensive to those of delicate sensibilities. Click at your own risk)
http://www.amazon.com/Reciprotools-RCT-A10-Reciprocating-Saw-Adapter/dp/B001CNHDR2


(IT converts a sawsall to accept various brushes and attachments like scrubbing brushes, grout remover blades, scrapers, etc)

 

[1911ly]

Something going on and out at the crown sounds scare to me. I would think it easy to run it in to the end of the barrel. Ruining the crown. IMHO a brass brush carefully held at the end of the bore. Centered (keeping the brush partially out of the bore) ran for a few seconds would be harmless to the crown. The barrel is steel. The bristle is brass. I guess you could damage it but if you are at the this point the barrel is probably shot out and the point is mute. It's a last ditch effort anyway.

I never let my barrels get cruded up. I usually clean it every range trip or 500 rounds. What ever comes first, It's easy. It's cheap to do and takes minutes. Just keep it clean.

 

[rvb]

I also don't get why I am chastised for chucking up a brass brush in a drill to clean the crud at the end of a barrel. But it's better to chuck up a brass screw and go at it? That seems more likely to be overly aggressive. But to each his own. And someone always has a better way then me any how

While I've never used the screw head method (never needed to try), I've heard it before and it makes sense to me. You're using it w/ the lapping compound to "re cut" the crown. The barrel is already f'd, I would lean on sloughfoot's experience and give it a try. You won't be hurting anything; doesn't sound like you can make it worse. (A brass brush is probably still held together w/ some steel center and odds are not perfect straight. it makes me cringe, too, to have one in a drill spinning in the bore by the muzzle).

You might check the twist and make sure you got what was advertised.

You could also take it to a smith and have the crown cut properly if your willing to risk 'investing' a few bucks in this barrel.

The crown picture in the original post doesn't look aweful to me (no dings, etc), but you really can't see anything.... which is weird. in the bore, I'd expect that to be somewhat shiney, maybe see some evidence of lands/grooves, even w/ bad lighting in the photo. And at the crown I'd expect to see some rifling definition (maybe lapping it in as suggested would get you some of that definition). I suspect there is more f'd about that barrel than the crown.

-rvb

 

[Leo]

The old brass round head screw with valve lapping compound is an old trick to maximize smoothness of a decent barrel crown. It was a quick trick that I heard about in the 1970's, it is probably older than that. They still sell brass cones in gunsmith tool catalogs that are made for that use. I have never done it on a fresh barrel. I have tried it on some tired old barrels on military surplus rifles. The lapping compound will not remove enough material from a truly bad crown to make much difference. If you have (or have a buddy with) an open spindle lathe, center it up in the chuck and lop about 3/8 inch off. Then make a facing cut. Some people like a small inward taper to brotect the crown from bumps, but the bullet does not care. If the rifling is gone, a perfect crown means nothing. At 3000 fps, that bullet travels the barrel in less than 1/100 of a second, it either grips or skids. There is not much time to get that job done.

I never spin a brush (or a proper lap) in rifling. The grooves go length wise with a slight spin, that is how an effective brush or lap should follow. That spinning brush method is for shotgunners trying to work plastic build up from cheap shot wads out of smooth bore barrels. I just use a rag soaked in acetone. 5 minutes later, the plastic fouling falls out like crumbs off an apple turnover.

Compared to barrels on other rifles, even middle of the road quality barrels are pretty cheap for an AR. The fact that they are pre chambered/finished and as easy to install as shock absorbers on an old chevy eliminating the gunsmithing, I do not put much effort into salvaging an old AR barrel.

 

[turnerdye1]

Yeah this thing and an older barrel and to be honest I'm tired of messing with it. I'm just gonna invest in another barrel around black friday time to see if I can find some good deals. What should I do with this old barrel?

This new barrel... I'm thinking a 16" M4 profile with a midlength gas system in 1:7 twist.

Then after I get out of the academy I'll be investing in a BCM 10.5" patrol rifle and my current rifle will just be a plinker.

 

[silentvoice71]

Check with palmetto state arms, primary arms too as they have sales all the time

 

[1775usmarine]

Now if you had gone to boot camp USMC style that would never look like that. You would of had that thing scrubbed till it was mirror like with a q-tip and CLP.

 

[BGDave]

The old brass round head screw with valve lapping compound is an old trick to maximize smoothness of a decent barrel crown. It was a quick trick that I heard about in the 1970's, it is probably older than that. They still sell brass cones in gunsmith tool catalogs that are made for that use. I have never done it on a fresh barrel. I have tried it on some tired old barrels on military surplus rifles. The lapping compound will not remove enough material from a truly bad crown to make much difference. If you have (or have a buddy with) an open spindle lathe, center it up in the chuck and lop about 3/8 inch off. Then make a facing cut. Some people like a small inward taper to brotect the crown from bumps, but the bullet does not care. If the rifling is gone, a perfect crown means nothing. At 3000 fps, that bullet travels the barrel in less than 1/100 of a second, it either grips or skids. There is not much time to get that job done.

I never spin a brush (or a proper lap) in rifling. The grooves go length wise with a slight spin, that is how an effective brush or lap should follow. That spinning brush method is for shotgunners trying to work plastic build up from cheap shot wads out of smooth bore barrels. I just use a rag soaked in acetone. 5 minutes later, the plastic fouling falls out like crumbs off an apple turnover.

Compared to barrels on other rifles, even middle of the road quality barrels are pretty cheap for an AR. The fact that they are pre chambered/finished and as easy to install as shock absorbers on an old chevy eliminating the gunsmithing, I do not put much effort into salvaging an old AR barrel.

Thanks for the acetone tip. Never heard that before.

 

[Leo]

Thanks for the acetone tip. Never heard that before.

After the barrel is clean, be sure to swab it lightly with oil be fore you put it away. Since the acetone cleans deep, there is nothing left to protect against rust.