Are all bolt carriers chrome lined?  Even the ones on E-bay?

Every bolt carrier I have ever seen including no-name $115 complete bolt/carrier assemblies have been chrome lined internally.


I think some of what matters is: staked key screws and then some are chrome lined externally which eases cleaning. The les baer BC is totally different and possibly a superior design but I am not sure.

On general principles, I don't buy anything on e bay.  Too many crooks there for my taste. If you need to find a used carrier, or live where there aren't any gun shows to get a carrier "in person", I'd recommend the equipment exchange section on this site.  The vast majority of people who advertise on this site are honest folks who are selling good quality stuff[:D]

shamayim, you stated that, "I don't buy anything on e bay. Too many crooks there for my taste."  

Have you been ripped off personally?  

I've sold and bought quite a bit on E-bay and every single transaction was a good experience (about 40 or 50 transactions).  At the same time, I've bought from people off of the exchange and all the transactions eventually turned out well.  There's always a risk when dealing over the internet.  To say there are too many crooks on E-bay is misleading in my opinion.

Dan

As for the original question "Are all bolt carriers created equal?", only Colt and Bushmaster are magnetic particle inspected to insure against cracks or flaws that could cause catastrophic bolt failure or injury.

What is magnetic particle tested?

Magnetic particle inspection is a nondestructive inspection methods used for defect detection. The method is used to inspect a variety of product forms such as castings, forgings, and weldments. The only requirement from an inspectability standpoint is that the component being inspected must be made of a ferromagnetic material such iron, nickel or cobalt, or some of their alloys. Ferromagnetic materials are materials that can be magnetized to a level that will allow the inspection to be effective. Many different industries use magnetic particle inspection for determining a component's fitness-for-use.

Some examples of industries that use magnetic particle inspection are the structural steel, automotive, petro-chemical , power generation and aerospace industries. Underwater inspection is another area where magnetic particle inspection may be used to test such things as offshore structures and underwater pipelines.

The magnetic particle inspection method along with liquid penetrant inspection is one of the oldest and most widely utilized forms of nondestructive testing currently in use today. Magnetic particle testing uses magnetic fields and small magnetic particles, such as iron filings to detect flaws in components. In theory, it is a relatively simple concept. When a bar magnet is broken in the center of its length, two complete bar magnets with magnetic poles on each end of each magnet will result. If the magnet were cracked but not broken completely in two, a north and south pole will form at each edge of the crack, just as though the break had been completed. If iron particles were then sprinkled on this cracked magnet, these particles will be attracted not only to the ends of the magnets poles but also to the edges of the crack.

In magnetic particle inspection there are primarily two types of magnetic fields used to inspect parts, longitudinal and circular. Longitudinal magnetic fields are typically created by placing the part in a strong external magnetic field generated by a conducting copper wire that has been looped or wrapped to form a coil. A coil would be used to inspect such things as a steel rod or a valve from a car engine that might have cracks or inclusions in it. A magnetizing coils is a standard feature on a wet horizontal inspection unit but smaller field portable coils are also available. A wet horizontal unit is a large stationary piece of equipment that not only has head-shot and central conductor fixtures but also has a coil permanently mounted to it. The magnetic particles are held in a suspension of either water or oil and are supplied by a pump and hose on the system. These particles are of either the visible type, which means that they can be seen in normal white light, or the fluorescent type. Fluorescent particles require the use of a blacklight, which causes the particle indications to illuminate. This is much the same as causing a blacklight poster to glow in the dark.

Isn't there something to do with pot metal.. yadda yadda and such?????

Nope.  Read too many horror stories on this site about folks who got screwed royally, and got no assistance from e bay.  On the other hand, when the very occasional crook does a job on this site, the folks here get the word out immediately, and I have several times seen enough pressure brought on the guy who didn't deliver to either get the item shipped, or a refund made.

Never meant to imply that the majority of e bay transactions were problematiacal.  It's just that when one is, the buyer is out there on his own, with little or no help from the site.  Not the case here at ar15.com---and I like that[:D]


Re the MP designation,I agree that all bolt assys are not created equal.  All my bolts are Colt MP C marked.  On the other hand, bolt carriers are probably not as critical, tho 4 of my 5 are either Colt or GI milsurp (with the full auto shoulders cut back).  The one aftermarket piece I do have, tho, seems fine.  

WOW

Thank you!!