Sorry if this runs kinda long - About six months ago, I bought a Bushmaster lower from an individual. I just recently built it up. As I was putting on the buttstock, I noticed what appeared to be a scratch running along the spine of the left side of the mag well where it makes the 90 degree bend. I took it to a local gunsmith, who looked at it under a magnifier. He said it was a "forging crack", probably gotten in the metal during the cool-down process. It is covered by the finish, so I am pretty sure it was done at the factory. It looks like it hardly extends any at all into the metal; looks more like a scratch than a crack. He said that it would probably never cause a problem, just a cosmetic flaw, really. He said if I was really worried about it to contact Bushmaster, which I just did. Haven't heard back. How common is this? I have never seen it before. Is it something to be worried about, or just a cosmetic flaw? Anybody with any ideas/info, I would appreciate some feed back.

 pic?

IF it were mine Id be tempted to cut a chamfer into the crack and tig it back in and refinish. I wouldnt trust it not to spread.

I don't have any way to post a pic, sorry.

Any "crack" or fracture is not commonplace or normal.

However without a pic, who knows.

Send it back to BM, if it is " Cracked " they will prob replace it for free.

I've never heard of a forged reciever cracking before.

Sure it's not just the hard anodizing that is cracked? Is there any sign that the receiver sustained a sharp blow around where the fissure begins or ends? If there is, then most likely the crack occurred post anodizing.

Hard to tell though without pics. Why can't you post pics?    

If it is indeed cracked Bushy will replace it. I would be very surprised if it actually is cracked though.

I would not attempt any repair until Bushmaster gets back to you.
If for some reason Bushmaster does not take care of the problem, (Unlikely)
Then consider the welding aspect.

This is not a common situation.

http://www.ar15.com/forums/topic.html?b=3&f=118&t=241791

Check this out...I contacted Bushmaster and they will replace the defect, but since mine was an SBR it would take months to complete.  So I went to a welder and they ran a bead down the front and I smoothed it up and re-moly-resined it!

Contact Bushy if it is cracked.

Max

Quoted: Contact Bushy if it is cracked. Max

+1

I just got a note from Bushmaster tech support. They said it was probably what they refer to as a "straw mark, where some of the metal is folded during the forging process." Said if it was a crack, it would most likely be all the way thru the receiver. They said they would be glad to take a look at it. I guess the main reason I can't post a pic is that I don't own a digital camera. I will have to get a friend to take a pic of it for me. Thanks for everybody's input; I may send them a picture of it as well.

There's a Colt joke in here somewhere....

Quoted: I just got a note from Bushmaster tech support. They said it was probably what they refer to as a "straw mark, where some of the metal is folded during the forging process." Said if it was a crack, it would most likely be all the way thru the receiver. They said they would be glad to take a look at it. I guess the main reason I can't post a pic is that I don't own a digital camera. I will have to get a friend to take a pic of it for me. Thanks for everybody's input; I may send them a picture of it as well.

You can use a film camera. when you get the film developed, just ask for a picture floppy disk with the prints.
Costs like $1.99 or something like that. Then upload it to photobucket.com after you create your free account there, and we will help with the board code.

Is Bushmaster going to possibly replace it now that it has been welded?

I don't think that was his that was welded, rather someone else who posted on here, different gun.