Prescript: If someone feels my wording of a particular paragraph or location of a piece/part can be simplified or corrected for accuracy, please post a correction which you can then delete if I amend your changes to this post.  Further, If I have made a grammatical error, "speling errror"... Or use incorrect nomenclature in describing a part of the AR, please advise what term is best for clarification. I've noticed a lot of folks posting about ARs they purchased and then ask "How did I do?".  This reference, if tacked, can be here as an easy reference to allow a potential purchaser the knowledge to ensure, they KNOW how they did or will do if they decide to purchase a used AR.

A main reason the AR15/M16 platform is so popular is because it's Mil-Spec.  What is Mil-Spec?  Mil-Spec means that the parts are all built to a Military Specification that not only ensures a quality weapon, it ensures the parts are uniform which provides for easily replaceable and interchangeable parts.  When looking to purchase a used AR15, or trying to identify a potentially used AR, I recommend a potential buyer inspect some or all of the following areas, parts & pieces as detailed below.

The reason for this post is that a less than trustworthy dealer may sell a parts gun and label it as a new weapon or perhaps the dealer himself doesn't know what to look for in regards to a potentially FUBARed AR.  Or a Newbie may not know that what he's looking at isn't a new AR, it just a doctored weapon or one that was kept in relatively good shape by the previous owner.  While some signs of use and neglect are obvious, others aren't so easy to spot.  The best defense against being taken in as a sucker is to arm yourself w/ knowledge... So what do you inspect and look for on a potentially used AR or an AR advertised as "used"... If you really want to know, read on-

A2 fixed position butt stock-

Are scratches present on the shell of the stock?  A new A2 butt stock's appearance is a dull gray. (At least on all my Bushmaster "BM" ARs)  Rubbing, or years of light scratches, and oiling the stock tend  to turn the stock a shiny black. (Which to some can be more attractive than a brand new stock)  Light scratches can easily be rubbed on by contact with anything from a gun case to fingernails.  These minor scratches are essentially a non-issue as lovingly rubbing them with your thumb or applying a little oil will make them disappear and allow the stock to have a uniform finish/appearance.  Usually a new stock has oil "blotches" present near the rear sling swivel, around the butt plate and where the stock attaches to the receiver.  These areas appear as a darker "blotch" stain to the plastic. If this proves too ugly for one's taste either oil the rest of the stock to match, which may not be the best idea as your face will be resting on the stock during use or Birchwood Casey Gun Scrubber can degrease the blotched areas but may turn the stock an ugly gray/white.... My personal recommendation is to leave the blotched areas alone as again, they are normal.

The butt plate itself of an A2 stock should be free of cracks and breaks w/ sharp checkering as new from the factory.  Signs of normal use are light scratches on the sides of the plate and dulling of the diamond checkered plastic. Also look for flat spots on the diamond checkering which can occur due to clearance of a jam by striking the butt stock on a hard surface and/or by propping the weapon against a wall or bench w/ the butt plate on a hard surface such as concrete.

Collapsible stocks-

C-stocks appear shiny black when new.  Oiling does not tend to stain or darken the appearance.  Signs of use would include dents, scratches or cracks on the stock itself.  The locking latch mechanism should lock/unlock positively with ease.  If the stock does not lock/unlock positively, the latch mechanism may need adjusting.  This is another spot to look at closely as stocks should come from the factory set up correctly- perhaps it's been adjusted by a previous owner.  Look for marring or scratches on the adjusting bolt.  Further, ensure the plastic on the latch mechanism is not broken.  I have personally witnessed an "as new" Olympic Arms C-stock that had a hairline crack on the plastic locking mechanism which was only visible by my discerning eye and when an acquaintance was inspecting the weapon for purchase I pointed this out to him.  (He still bought the Oly as his intention was to swap it out w/ a more robust C-stock than the standard offering from Oly)

C-stock lower receiver extension tube-

This is the piece that houses the recoil spring and buffer.  It is also referred to as the "buffer tube".  On a collapsible stock, the telescoping operation of the stock wears on the buffer tube.  The more the stock has been adjusted in or out, the more wear.  Early signs of wear are just a "scuffing" or "marring" to the phosphate finish of the buffer tube and it's  location may vary.  Extensive wear would mean the wear has removed the phosphate finish where contact is made between the buffer tube and the stock.  These spots would most likely appear silver as under the phosphate finish is bare aluminum. (Personally I have yet to witness a C-stock buffer tube worn to silver)

A2 Butt Stock & C-stock-  

Upper spine.  Look for wear caused by repeated operation of the charging handle.  Under normal us, it's common for the charge handle to rub against the very top of the AR's stock.  Over time a wear mark will appear as a marred line running lengthwise on the top of the stock where the charge handle overlaps the stock when pulled to the rear.  It's presence lends an idea of how many times the charge handle has been operated.

Hand guards-

Much like the collapsible style butt stock, hand guards are usually a shiny black from the factory.  Normal wear will cause the hand guards to appear a a bit more shiny black.  Heavy use or neglect will result in the hand guards being broken, cracked, dented or perhaps a bit of glass embedded from breaking out windows with the weapon and sweeping the shards out of the window's frame w/ the forearm of the rifle.  Depending on what is considered normal wear, the hand guards can also melt during prolonged sessions of high volume magazine dumps.  This melting usually appears first at the front of the top hand guard where the gas tube becomes super heated.   As the front of the hand guards are located very close to where the gases are vented from the bore into the tube- this is the location where initial melting will occur.  I have personally began to melt the upper hand guard at it's front after rapidly bump firing 5 magazine through my BM M4.

Charging handle-  

Remove the charge handle and inspect for wear on the sides and top of the CH itself.  If there is considerable wear to the point of being shiny along the length of the charge handle, you get an idea of how many times the weapon has been charged.  Remember, the weapon is normally charged once for every 30 rounds.  However, if a person were to manually charge the rifle for the first magazine and then tactically reload or shoot the weapon dry and then release the bolt via the bolt release- hundreds of rounds could be fired before the charging handle is manipulated again.  So what does the wear on a charge handle signify...  The wear on the charge handle indicates how many times the weapon has either been charged or cleared, not necessarily how many times the weapon has been fired.

Lower receiver-  

Another indication of manual manipulation of the charge handle appears in two small lines on the back of the receiver where the upper and lower receivers mate.  The charge handle rests above and slides over a flat area on the top of the lower receiver immediately in front of the stock.  As the charge handle appears somewhat like an inverted "U" the wear to the lower receiver is two parallel "scratches" which run in line to the bore of the rifle.  The more the charging handle has been operated, the more wear to this small portion.  If there are two distinct silver lines on this flat area, this indicates the charge handle has been operated enough times for the charging handle to wear through the lower receiver phosphate finish to the bare aluminum of the receiver.

Obviously the appearance of your lower is/can be important.  Look for scratches &/or touchups etc. to the external finish of the lower receiver.  The finish should be consistent and a nice dark black.  (Or Colt Gray if you've got an old Pony on the side)  A quick way to gauge if the lower receiver on a used or suspected used lower receiver is to check the magazine well itself.  Each time a magazine is inserted into the magazine well, wear to the finish occurs.  The more finish removed from the inside of the magazine well, the more use the lower itself has seen.

Fire Control Group (FCG)-

The only piece of the FCG which can be easily inspected w/out removal of the FCG is the Hammer.  I tend to focus on just the hammer when trying to determine the weapons usage which is easily done by cocking the hammer and  visually inspecting the face of the hammer for any wear.  A recurring theme here is that like most all other parts on an AR, the hammer is black to dark gray when new from the factory.  Normal wear will show on the face of the hammer where it contacts the bottom of the carrier during recoil and where the hammer impacts the firing pin just prior to detonation of a freshly chambered round of ammo.  Depending on what exactly you're looking for in the weapon being inspected, normal wear would be a fair amount of silver showing on the face of the hammer.  

Signs of heavy usage to the hammer would be the presence of  a small roundish dent in the face of the hammer caused by incalculable impacts with the firing pin.  Further signs of abnormal wear can occur on the "notched" area on the face of an AR15 hammer.  This is caused most likely by the previous owner "bump firing" or having an incorrectly timed FCG.  The hammer was notched to hang up the action if the disconnector were to be illegally altered for full auto fire.  An M16 hammer lacks this notch, instead being smooth on the top of the face.  IIRC, the notch usually hangs up on the firing pin itself which also leads to wear on the collar of the firing pin.  An M16 bolt carrier conceals the firing pin which would further prevent the hang up as described w/ a commercial AR15 Hammer/Carrier/Firing Pin.

By Tweak:  About the hammer wear from bumpfiring. If your hammer follows the BC into battery you've got timing issues that need to be addressed (usually the tail of the hammer striking the top of the disco and that's a place to look for wear) as the hammer is released by the trigger for each shot during bump firing. A lot of hammer / firing pin interferenc is caused by dry cycling the rifle as the hammer sits lower when it's retained by the disco (as it would be after a shot is fired) whereas in rifles that are dry cycled a lot the hammer is resting on the sear.

Added 10/02/2005:

When inspecting the FCG on a used AR15, it is also noteworthy to look for signs of impact on the top of the disconnector at the point the hammer tail would come into contact if the AR has timing issues.  This impact would be nothing more than a small dent to the disconnector from the tail of the hammer unacceptably contacting the disconnector during cycling of the action.  If the sign of contact is there, and timing issues are present, it may just require a simple correction to the disconnector itself, or replacement of the disconnector or  FCG.  (I mention replacement of the entire FCG as if the hammer has plenty of miles on it and a change of one part is warranted, sometimes it's best to replace all the related parts to ensure years of trouble free reliability)  When looking at purchasing a used weapon, it's important to note even easily correctable issues such as the replacement of a disconnector. IMHO even small issues should be reflected in the asking price.   For the best technical advice should one spot a dent to the disco on their AR or for one who may potentially purchase an AR w/ evidence of incorrect timing... I'd suggest a visit to the "Troubleshooting" forum on AR15.com.

By Tweak: Strikes there are common, it's the amount of movement transferred to the disco that matters.

Buffer-

The buffer is the metal piece that is held captive in the buffer tube and as it's name implies, buffers the recoil impulse when the rifle is fired.  It fits inside the recoil spring and is held captive by a spring pressured detent.  Normal wear would be a circular shaped indentation correlating to the size and shape of the back of the carrier.  A deep circular indentation to the face of the buffer would signify lots of use.

Another form of wear to the buffer, which can be disappointing to discover but can be considered normal unless corrective action is taken, is a series of scratches running across the face of the buffer where it contacts the back of the carrier.  These scratches are caused by small burrs on the back of the carrier left after machining of the carrier. These burs are found on each side of the channel that is machined at the bottom of the carrier to allow the carrier to pass over the buffer retaining indent without actually contacting the indent.  When you take down the weapon and pivot the upper receiver away from the lower- the burr(s) on the back of the carrier travel across the face of the buffer which can cause a series of slight scratches on the face of the buffer. If the burs are present they really dig into the face of the buffer each time the upper receiver is mated to the lower which can cause nasty gouges. These gouges/scratches are unsightly and with some careful sanding/honing on the burs of the carrier can be avoided.  The presence of scratches are probably more abnormal as they can be avoided and they are an indicator of how many times the lower/upper receiver have been pivoted open/closed. Lots of gouges begin to look like an asterisk * on the face of the buffer.


Carrier-

Are the contact surfaces worn?  Wear tends to appear on several mating surfaces on top and bottom due to contact where the carrier slides inside the upper receiver.  When new or slightly used these contact areas, which serve as a guide during cycling of the action, are black.  When cycled enough, the black finish wears off and the mating areas appear shiny silver and should be smooth as glass.  IIRC, there are four of these mating surfaces; two on top & on either side of the gas key & two on the sides of the carrier near the bottom.

The bottom of the carrier contacts the hammer when the action is cycled.  This action is necessary to cock the hammer.  As the carrier continues back into the recess of the buffer tube, the hammer is in constant contact w/ the bottom of the carrier. It is at this smooth flat surface on the bottom of the carrier that wear will appear.  The black finish will be worn to a shiny silver and such wear should be considered normal for a used AR.  Also, the carrier will ride on the top of the next round to be stripped from the magazine.  This may cause brass transference to the bottom of the carrier and is considered a normal, non-issue.  Excessive wear would be near impossible, but depending on the amount of wear to the area, one can more clearly discern how many times the carrier has cycled the action.  (Either by firing or manually manipulating the action)

Also the back end of the carrier where it contacts the buffer may help some in determining the amount of use.  As the finish is black when new, the carrier to buffer impact will wear to a shiny silver but this tends to take a lot of time therefore is a poor indicator of past use.  As no other contact is made by the carrier to the upper receiver, the sides etc. should remain black for the carrier's life.  Only through excessive cleaning, abuse or neglect will the finish of the carrier outside of the contact areas wear.

Lastly the front of the carrier, where the bolt protrudes out of the front of the carrier, will show wear.  This is caused at the point the carrier contacts the barrel extension when the action is closed and will appear to be no more than a shiny silver circle on the outside edge on the face of the carrier.

Bolt-  

Once again, the bolt is all black when new.  If oiled, it appears dark- nearly shiny.  If degreased, it can appear a dull grayish phosphate.  Signs of use and wear would be found on the bolt face, locking lugs and carbon build up at the back of the bolt just behind the gas rings where the bolt tapers to surround the firing pin.  

During normal use a circular wear area appears where the base of the shell comes into contact w/ the bolt face.  Under 1K rounds and w/out a cleaning this circle may be brass colored as it is literally brass transferred from the base of the rounds fired in the weapon.  This brass can be removed through judicious cleaning.  Eventually the phosphate is worn off and the circle will appear silver and tend to collect less brass transference.  A silver circle would indicate a fair amount of use on the bolt.  Neglect, abuse and improper reloads can lead to scratches, and or pitting on the bolt face which should be considered excessive/abnormal wear.

The bolt locking lugs as new are all black and should have sharp corners. Plus, there should be 7 lugs present. Signs of normal wear include wear to the point of being silver anywhere on the lugs.  Signs of excessive or abnormal wear would include cracks, chipping, or pitting present on the lugs.  Two of the lugs on the bottom of the bolt may display brass collection from riding over the rounds in the magazine when the carrier is traveling backwards during recoil or when coming into contact with a round being stripped from the magazine by the bolt when loading a round into the chamber.  This is normal.

Abuse of the bolt would most likely occur from overzealous or improper methods of cleaning.  This definitely includes any scraping of carbon off the rear of the bolt where the firing pin travels.  Basically, the rear of the bolt tapers like a "bell".  At the large mouth of this bell, just behind the gas rings, carbon loves to build up.  If not routinely cleaned, the carbon is damned hard to remove.  If a person were to use, oh let's just say a knife blade or screw driver to scrape this carbon buildup off the bolt- damage to the chrome plating on the bolt may occur.

Cam Pin-  

This is the pieces that operates inside the cutout in the carrier and ensures the bolt rotates during the cycling of the action.  As new my Bushmaster Cam Pins are a gray/silver molybdenum finish.  (Moly dry coat)  The more the action is cycled or the weapon is fired, the more wear appears on the cam pin.  Slight scratching or a marring mark caused by the Cam Pin rotating during cycling would be considered normal wear.  Pits through neglect or scarring would indicate abnormal or excessive wear. Worse case scenario, the cam pin is broken or cracked.

Firing Pin-  

The firing pin should be chromed silver in appearance as new.  Some black carbon from factory test fire would be considered normal on a new weapon.  The collar on the rear of the firing pin at the area which contacts the hammer should be uniformly round and smooth w/ sharp corners at the front of the collar.  Such as (]=[]========>  

The second collar in front of the hammer contact area is present to ensure the firing pin does not travel too far forward of the bolt and pierce the ammo's primer as well as ensuring the firing pin is retained by the firing pin retaining pin. (The little do-hickey which resembles a hair pin is the firing pin retaining pin) This collar should have sharp corners as detailed in the paragraph above.  I have seen a Bushmaster firing pin where the firing pin retaining collar had literally been mashed out of spec due to contact w/ the notch in the face of an AR15 hammer. Thus the firing pin somewhat resembled (]=(]========>  This indicated lots of use/wear but the pin continued to function as designed.   I have no idea how an AR15 firing pin could become bent, but that would obviously be a sign of certain abuse or neglect. Normal wear would probably include a dulling of the silver chromed finish to a dull luster due to lots of scratches during cycling of the action and cleaning of the pin itself.

The tip of the firing pin which contacts the primer during ignition should be uniform and round.  If it appears flat, this may be because excessive sympathetic contact to the primers caused by inertia was present prompting the previous owner to judiciously(?) hone or flatten the firing pin to ensure an accidental discharge would not occur.  Ensure the firing pin continues to reliably ignite all forms of readily available ammo.  (i.e., commercial and military surplus) Excessive wear to the tip of a firing pin would be an overly flattened tip affecting reliable primer detonation, the presence of a chipped tip or no tip at all due to it being broken off.


Shell Deflector-

The shell deflector is an easy place to spot use.  Ejected brass shell casings bounce off the shell deflector to save the gifted few left handers of the world from cosmetic damage to the face of the shooter.  (Lefties BTW were personally sent by the almighty God to add flavor to an otherwise bland right-hand-only world)  Each time the weapon is fired, a corresponding amount of brass transfers from the spent shell casing onto the shell deflector.  However, I have found that w/ a bit of Hoppes # 9 and a good brush, the brass can be removed so do not rely on the lack of brass marks on the shell deflector to aid in determining the amount of use a particular AR15 has seen.  Do check to ensure that the finish of the deflector has not been worn through to bare aluminum.

Forward Assist And All Other "High Spots"-

Wear to the forward assist and other "high spots" indicates how much the gun has traveled more so than how much it has been used.  Any silver appearance on any high spot on the weapon which includes but is not limited to, the forward assist, shell deflector, carry handle, sight adjustment knobs, front sight post etc. allows a person to know how many miles the gun has traveled.  In a soft case or in the loving hands of the former owner, the finish is going to have tell tale signs of ware with time.  Obviously this rubbing off of the finish is normal but an example of excessive or negligent wear would include dents, scratches etc.

Upper Receiver Charge Handle "Catch Hold"-

On the left hand side of the upper receiver, where the charge handle's latch catches hold to the upper thus holding the CH captive when not being manually manipulated, is a small raised "bump".  This bump is nothing more than an integral part of the upper receiver and as new has sharp corners.  Through normal wear, the bump will become silver as the finish to this part of the weapon is easily removed by the metal charging handle latch.  A well worn CH "Catch Hold" is indicated by the rounding of the sharp corners and eventually can lead to part of this bump being completely worn down.  This can cause the CH to fail to latch to the upper receiver after the weapon is charged and the bolt returns home. A person would only realize this if they locked the action open and then manually pushed the CH forward where it would then fail to latch to the upper.  If someone has pieced together an old used upper receiver with a new barrel and parts, this little "Catch Hold" bump will give away the upper's actual history of use.

Gas Tube-

The gas tube is found underneath the top hand guard.  It is shiny silver as new.  Through normal use there may be some carbon build up at the front of the tube as some gas escapes at the location of where the gas tube is pinned into the front sight base.  Under normal use, slight discoloration of the gas tube will occur.  A sign of heavy use would be a very discolored gas tube which could extend down the front half of the gas tube or further towards the upper receiver.  The color may be gold, dark gold, brown or black.  Signs of abuse or neglect may include a bent gas tube which may be caused by striking the hand guards so hard against an object as to break the hand guards allowing the hard object to impact the gas tube or by repeated high volume mag dumps which could begin to melt the gas tube thus causing it to "slump" down along it's length. (I must admit, the slumping gas tube due to lots of mag dumps is just my theory as I've never seen an AR ran so hard)

Lastly we'll cover the most important part of the weapon,  the barrel and related parts.  

Barrel Exterior-

The barrel can be a deep shiny black if a light coat of oil is present.  Every time I've traded or sold an AR a thin coat of oil has been applied to the metal surfaces which results in a darker more uniform appearance.  If a degreaser is applied, the finish will appear to be thin black to grayish.  This is all purely cosmetic.  What is important is that the weapon has not been haphazardly thrown in an unprotected gun rack allowing the metal surface of the barrel to be worn.  On most ARs there are small rings on the outside of the barrel left over after machining.  These can become flattened through prolonged use by the barrel rubbing on hard surfaces & objects.  If the AR in question is new, you can pretty much file your fingernail on the barrel.  Wear would make the exterior of the barrel smooth, which may not necessarily be a bad thing.  What you don't want is the finish to be worn off allowing the barrel to rust if subjected to moisture/humidity.  A well worn barrel will be a dull silver on the outside.  Obvious signs of abuse or neglect would include the presence of scratches, gouges, rust or pits on the externals of the barrel.

Barrel Bore-

Arguably the most important area to scrutinize, if your AR has a bad bore it won't be accurate.  Most quality AR15s will have a chrome lined bore.  Some of the more budget minded AR suppliers skip the chrome application to save the end user money and further, some varmint or match barreled ARs lack the chrome lining to enhance accuracy.  If you are going to purchase an AR to use as a rattle-battle rifle, you'll want the chrome bore as it tends to be more forgiving if one should have to neglect a routine cleaning schedule.  A good chromed bore will display crisp- well defined rifling which will be shiny silver when cleaned.  A barrel that has not been cleaned well or has been neglected will appear to have a "dark bore". That is to say, when one uses a bore light to look into the barrel the lands and grooves of the rifling will not reflect the light very well giving it a gloomy dark tunnel appearance. If a bore appears to be "dark", ensure it's cleaned before you inspect it.  If a factory rifle has been test fired for say 5-15 rounds and then sits in a case or on a shelf for several months- chances are it's just dirty, not darkened through abuse or neglect.  Also, ensure that there are no dark spots which could mean the chrome lining has flaked off or that there has been pitting due to corrosion.  (Newbie warning!  There will be one dark spot in every AR15 barrel...  It's the gas port which is located at 12 o'clock on the barrel and corresponds to where the front sight base is.  This is the hole that allows gas to exit the barrel and enter the gas tube to cycle the action.  To some, it's initial discovery is horrifying until you realize- it needs to be there!)


Flash Suppressors, Muzzle Devices & Crowns-

The flash suppressor will be present on the end of the barrel if we're talking about a "pre-ban" configured weapon.  Wear to the FS will include shining of the FS usually found on the very tip, but can also be present on any high spots.  This can be caused by insertion and retrieval from a soft case where the rifle is slid into the partially open case muzzle first or by attaching a bayonet to the AR.  Damage through abuse would include dents, gashes, chipping or cracks/breakage caused by severe abuse such as breaking out glass windows w/ the muzzle or dropping the weapon muzzle first onto a hard or uneven surface such as concrete, pavement or rocks.  Severe wear may be present caused by the weapon being transported muzzle down in the cab of a vehicle.  The dirt and small rocks that are captured in the carpeting/matting on the floorboard of a vehicle really shine up a flash suppressor in a hurry.  The main concern when a flash suppressor shows heavy wear is that if the weapon has been transported muzzle down in a vehicle as described above, small particles of dust can collect at the muzzle end of the bore.  If this is not removed before the weapon is fired accelerated wear to the rifling at the muzzle can occur. The same wear concerns detailed above apply to post ban politically neutered ARs which have a "compensator" as opposed to a flash suppressor. (Although attaching a bayonet is not a cause of wear to a compensator)  

The big worry is when there is no muzzle device attached to the weapon such as a Varmint rifle or politically neutered AR.  When the muzzle is "naked" the crown is exposed which in turn subjects the crown to wear and/or damage.  Since the crown is the last part of the weapon to have an effect on the bullets path from the weapon, it is imperative that no dents or dings are present to the rifles crown.  Neglect of a "naked" muzzle could easily lead to a damaged crown or the rifling at the muzzle end having accelerated wear due to debris collecting in the first few inches or so of the muzzle.  Once the weapon is fired with dust/debris resting inside the muzzle, the rifling will suffer from abnormal friction caused as the bullet passes through the dust/debris.

HTH.

Sly

Tagged for future use.

Sly

BTT for the weekend-

Sly

damn good info !!!

but how many will use it ??

Thanks for the information

I have practived reloading in all the lowers I have had a lot more at home with out "using" the lower than I have at the range.  Magwell wear is not representative of rounds fired.  I have NEVER seen an AR that did not have the 2 scratches where the charging handle wears either and its not indicative of anything negative.

Great post and lots of good information. However, I will have to call "BS" on this line:

" Further signs of abnormal wear can occur on the "notched" area on the face of an AR15 hammer. This is caused most likely by the previous owner "bump firing" or having an incorrectly timed FCG."

Correct me here if I'm wrong, but " Bump firing" cycles the action and FCG the same way as normal semi auto firing, just faster, correct? Therefor,  the wear on the FCG would not differ in any way. Correct?

I smell smoeone who has a dislike of "Bump firing" attempting to blame it for abnormal wear on the weapon. Now tell me I'm wrong.

Quoted: why would you tag your own thread?

It was a tag for future content, not so I could find my own thread.  If the need to add additional information should arise, it can be added near the top of the thread.  IIRC, each post is limited to 8,000 characters and each of my posts above the tag are just under 8K.  Perhaps I'm mistaken on the 8k character limit?

By Tweak: very few after it falls into the Archives

If it falls into the archives, that's fine.   The focus of the post was to be a reference for what to spot on a used AR or if someone should happen to purchase an AR and suspect that it was a mix of new & used parts.    

While I'm not a sponsor of the site, I am a member.  The only thing I have to offer is my own view points and additions to discussions.  (My comments are always open to corrections if my interpretation or view points should be proven incorrect)  If my information is not worthy of a tack, it will go to the archives and folks can continually regurgitate answers to new AR owners if they suspect they may have been suckered on a recent purchase.  Further, some just don't know what to look for and it's because of information they remember stumbling across in the past that they may find merit to a post such as mine.

As an example, I've seen a few AR15s for sale @ gun shows which have a new lower installed and a used "post ban" upper that has been recently threaded for a flash suppressor.  The give away to the age of the upper is that it lacks a bayonet lug on the front site post.  Now, how many folks new to the AR world would understand that my statement above concerning bayo lugs would apply to all upper manufacturers except Colt because they were voluntarily neutering the bayo lugs off their uppers before the ban?  Perhaps today my long winded post just seems like a shotgun pattern of information, but in weeks or months- it may prove beneficial to more than few users of the site.  If it gets lost in the archives, I'll just be sure to either direct folks to the information or realize that my attempts to aid the site where a lost cause and move to other discussions.  

I hope the above makes sense, it's difficult for me to understand why folks seem to have to explain their attempts at helping others.  Then again perhaps I take the questions posed here a bit too personal due to the seperation of emotions behind keyboards?  In the end, I'm just trying to help.

Sly

Quoted: Great post and lots of good information. However, I will have to call "BS" on this line: " Further signs of abnormal wear can occur on the "notched" area on the face of an AR15 hammer. This is caused most likely by the previous owner "bump firing" or having an incorrectly timed FCG." Correct me here if I'm wrong, but " Bump firing" cycles the action and FCG the same way as normal semi auto firing, just faster, correct? Therefor,  the wear on the FCG would not differ in any way. Correct? I smell smoeone who has a dislike of "Bump firing" attempting to blame it for abnormal wear on the weapon. Now tell me I'm wrong.

You're jumping to conclusions too fast man-  I think bump firing is the best legal substitute for full auto.  And as long as class III remains so damn far out of my grasp due to the cost-  I'll continue to be counted among the bump firing crowd.

My attempt to explain how I feel BF would affect the hammer is that not all ARs seem to do it to the same extent.  Occasionaly you'll get off a few round burst and then the hammer follows the carrier resulting in a light primer strike.  This then ceases the bump firing and the weapon has to be manually reloaded.  When the hammer follows the carrier- it's my understanding that the hammer, which is then in constant contact w/ the carrier, will hang up on the firing pin.  It's not enough to lock the action open per se- but it does allow unhealthy contact at the hammer notch and the firing pin.  Hope that's right, but I'm always open to correction for the sake of accuracy.

Worse than no information, is bad information.

Sly

Quoted: I have practived reloading in all the lowers I have had a lot more at home with out "using" the lower than I have at the range.  Magwell wear is not representative of rounds fired.  I have NEVER seen an AR that did not have the 2 scratches where the charging handle wears either and its not indicative of anything negative.

Devl, if you read through my entire long winded post I have two things to say to you for adding your comment.  The first is "thank you" for taking the time and the second is- thanks again for adding you own imput to my post.

Of the two seemingly minor indicators of an AR lowers past usage which you pointed out Devl, the two scratches to the flat spot on the top of the receiver where the stock attaches would seem the most important, here's why:

These scratches do appear w/ relatively little usage of the AR.  Say one were to read a recent issue of SGN and see the article on building an AKM/AK pistol.  The one that states building a pistol of this type is as simple as ensuring the lower was virgin and is so noted on the 4473 during the sale.  So a fellow decides to build an AR variant instead of the AKM route and is in the market to purchase a "New, Virgin" AR lower receiver to build into a pistol.  He stumbles across "Joe Blow's" dealer table at a gun show who has a lower receiver advertised as "New".  How is the future builder to know for sure the lower has never previously been built into a rifle?  Obviously the best way to know is to verify w/ the factory that the lower is virgin and is therefore legal to build into a pistol configuration. Because there's a chance the lower was shipped from the factory as a complete rifle or a complete lower w/ butt stock...  But say this poor ignorant fellow skipped that because it sounded so simple to do in the SGN article, "Joe Blow" seemed like a knowledgeable dealer, the price was right and "Joe Blow" was even willing to put on the 4473 that the lower was "Virgin".  

So our hapless fellow builds the lower into a pistol and as he's out enjoying an afternoon session of high-cyclic bump-firing an ATF agent checks him out.  The agent turns out to be a grouchy SOB and takes down the SN and other information as he intends to fully check out the legality of the build.  A call is placed to the factory and they advise the agent that the lower in question was shipped to "Joe Blow's Thug Supply" as a complete rifle.  "Joe Blow" was only really needing an upper and butt stock for another customer but found ordering a complete rifle was cheaper, he could make more selling the halves so who'd be the wiser?  Our poor ignorant pistol builder, that's who's going to be wiser.  If he'd have just noted that it appeared a charge handle had been operated enough times to leave those tell tale scratches on the flat portion of the lower receiver perhaps he'd have gone to a place like AR15.COM and asked the right questions before committing a felony.  Our poor AR pistol builder comes into this story w/ a poop chute like (o) and in 5 years he comes back sporting one of these (O).

As to the mag well being a poor indicator of use, it's just as you stated Devl.  You *used* your lower more to do dry mag change practice at home, then you did during actual use of the weapon.  While that's not going to indicate much use, or even wear- the mag well will indicate that a mag has been inserted lots.  So if a person were to try to sell a lower used solely for dry mag changes at home and stated to a potential buyer, "Look at them fire control parts, there ain't a scratch on em- cause it's new".  Technically, that would be a misrepresentation as the previous owner personally used the lower to their own delight.  Hence, it's used but like new. I admit, this is thin- but when it's added as another indicator- it helps paint a more accurate detail of the weapon's past use. Say a dept. surpluses an AR which has only been used to train personnel in mag changes.  So the weapon looks to be in tip top shape, but the mag well exhibits little finish on the inside and marks where a missed re-load bashed the mag into the bottom of the well.  I'd pick up the AR and think, "Hmm, it's not new- but hell there's only wear to the mag well.  The upper is as new and the FCG hasn't a mark on it.  I'll buy it cause I personally don't care about the finish on the mag well. Better yet, the fact it's 'used' is also reflected in the asking price... Score one for Sly!"

Take care,

Sly

Edited to elaborate-

Point taken.

Now that you mention it Tweak, the AR that I recall having hammer wear had been experiencing hammer to disco contact. The owner had gone to monkeying around w/ a JP competition trigger which I eventually swapped his FCG back out for him w/ standard FCG so he wasn't always experiencing problems.   For a while the owner was beginning to lose faith in his carbine which I pointed out the carbine was fine- it was his ill attempts at transforming it into some sort of bastardized super paper puncher that was resulting in it going from an as manufactured defensive carbine into a hiccupping nightmare.  In the end the owner just needed it illustrated the difference between "reliable" and "modified".  While some have the know how to achieve the happy balance of a reliably modified weapon, it's IMHO that doesn't usually come w/ just buying an after market part and reading the instructions...

I'm also going to edit my post above under the "FCG" to note that one should inspect for signs of incorrect timing when purchasing a used AR as evidenced by the hammer tail striking the disconnector.  Luckily it's been far enough in between that I've nearly forgotten about timing issues.  Thanks Tweak.

I also noticed last night that in all my Bushmasters manufactured Post Sept 04'  the firing pin is protected by the carrier.  Whereas in my older BMs, the FP was more exposed by the commercial cut to the bottom of the carrier.  These new ones are better in my opinion as only the striking area of the firing pin is exposed.

By FRAGBAIT:  Point taken.

Sly

Quoted: Quoted: one should inspect for signs of incorrect timing when purchasing a used AR as evidenced by the hammer tail striking the disconnector. Strikes there are common, it's the amount of movement transferred to the disco that matters.

Noted above.

By I-M-A-WMD: These new ones are better in my opinion as only the striking area of the firing pin is exposed.

By Tweak: The new ones are the old ones.

If you're illustrating that the bottom of the carrier -aside from the auto sear trip area- is as found on an M16 carrier, I'm following you Tweak.  IIRC, the commercial 15 carrier had a slot cut exposing the firing pin.  So If we're on the same page; the 16 bolt was first, then some modifications which were the standard for a long time and now the manufacturers are understanding that an enhanced bolt w/ M16 profile protection to the firing pin is best.  If I'm reading you wrong there feel free to IM me Tweak.

Thanks much for your imput.

Sly