I can't make assurances on what other companies will do, but I can tell you what's reasonable and likely to happen with any reputable US manufacturer of firearms and ammo. If you are using a factory rifle and factory ammo (not a parts gun you put together, and not your buddies reloads), and you have a serios problem result, then the problem GENERALLY is with the firearm or the ammo and you need to notify the involved companies. They will want to investigate. That means they will ask you to send them the firearm, (all of it including the magazine and any broken parts) the ammo from what remained in the weapon after the problem, the box the ammo came in , the fired brass, and they will need a detailed and truthfull description of what happened. You can decide who you trust. Both companies will ask for these items. They need these items to determine what happened and whose problem it is.  Our policy is to investigate fully and do everything humanly possible to make sure the guy is happy with how it is resolved. I think most US companies have the same attitude towardds customer relations.
In a nutshell, if it isn't a parts gun or reloads (and that can usually be determined conclusively), then someone, either the gun mfg or the ammo mfg probably owes you a repair or a new gun (aside from things like sticking your barrel in the mud). I suggest if the problem occurs to you, save the parts needed for the investigation and make some calls. Record the name of who you talk to including how to recontact that particular person and make a decision on who you trust the most,  ( the gun mfg or the ammo mfg) and work with them. The gun manufacturers and ammo manufacturers can normally work well together to determine the cause, and you normally can expect them to be honest with you. I am not an attorney, and do not offer this as legal advice. If you disagree , that's fine. Companies live or die by their reputation. If they do not take care of customers, everyone in the world will know it fast and they realize that. For the value of a firearm they are not likely to play games with you. You might ask the question in advance. Ask the company how they will handle it if you have a problem. Something to think about if the box doesn't have any English language or US contact info on it. Jeff Hoffman, Black Hills Ammo

JackalAR,
I must have mised something. What offends you about my post? Jeff Hoffman

I would like to know what you are describing as a parts gun?

I custom build my own rifles and use nothing but high quality sub-assemblies from Colt, LMT, CMT, RRA, Magpul, Larue Tactical, Leitner-Wise, MGI, PRI.

Would that be a parts gun?

JackalAR,
I should have been more clear. We will always stand behind our products. What I meant to say is that if you have a factory gun and factory ammo, then unless you have contributed to the problem in some way such as plugging your barrel with mud before firing, then it is pretty clear that someone owes you a repair or replacement. If you however build your own rifle, or have a problem while shooting your own handloads, then the answer is plainly not as clear cut that SOMEONE ELSE has the responsibility to fix it. It MAY have been something you did, and that will have to be considered during the investigation. It is unlikely that simply putting a new upper on your AR would cause a problem. If however someone actually builds an AR from parts, and then had a problem, I would be more likely to suspect a possible problem with the gun than if the gun were factory built. Gun manufacturers feel the same way about reloaded ammunition. It might be great stuff, but if reloads are involved there is a higher probability in their mind of an ammo problem , than if the incident occurred with factory ammo. That doesn't mean that a manufacturer wil tell you to get lost, it just means that they still have to consider all the possible causes. If you built the gun or amo, you are a possible cause.  Jeff

Gorvibub,
Thanks for your input, that is my point. Springfield handled it very well. Chances are real good that the unknown gunshow ammo was actually the problem in that case.,but Springfield took care of the customer anyway in what looks to me to be a very fair manner, and they deserve the good reputation that comes with treating people right. Jeff