View Full Version : what to check when u have to buy an used ar15??
hey guys
sorry for my bad english
saturday i will buy an used k3b
i need help.. cause when i will watch the rifle... i dont know what to ceck .
the seller told me he shooted only 200 rounds.....
but ..how can i really know it????
what are the parts i have to look at??
excuse me for my bad english
ciao
andy
Before the pros come in, I want to try to answer!
Check the gas ring tension by standing the bolt carrier on the extended bolt to see if the bolt carrier falls down to the cam pin stop.
Check the bolt carrier and the upper for excessive wear. (Anything beyound typical finish marring from the cyclic action).
Look at the front sight to make sure there is no tale-tail sign of rust from lack of
A) Oil placed there every cleaning.
B) Non parkerized barrel under the front sight.
Look at the overall cleanliness of the bolt and gas key, try to determine how well maintained the rifle was. Cleanliness is not the biggest thing to look for, but if it does end up being sparkling clean, you have a pretty good idea that the guy takes good care of his things.
After you buy it, you might want to start out fresh by:
1) Cleaning it well.
2) Call BCM/Botach/G&R Tacticle and get yourself new bolt gas seal rings. New extractor spring and o-ring, a a silicone Birchwood Gun&Reel cloth, and some high quality CLP. You should also grab a few chamber brushes.
I personally don't see a low round count AR as a threat from a reputable manufacturer (This is more important than anything above I told you to look at!) because if the machine is built with good parts and is a properly assembled machine, it's service life is very long and trouble free.
If your looking at a low quality build and the barrel material is sub-par, you can not easily change that... you can buy a quality bolt carrier group and upgrade the normal wear items like extractor parts... but then your spending $160 on the BCG and $20 on the extractor to make the gun reliable/serviceable and you still might have a non chrome lined barrel made of low quality material that will wear significantly faster than a better rifle would.
So, back up a step and tell us what brand this used rifle is.
hi Larry
well
thanks for the info.
i hope to have understood all your instructions....
btw.. i have here a complete repair kit i purchase for my bushmaster...so if the rifle i will buy, an Olympic k3b car15, need it, i will change...
i need that info in case the rifle is not in good shape.. i can try to lower the price with the seller ;-)
and...as i livein italy... for me is not so easy to have parts...
i have here some new parts i want to swap.. i have a vltor emod stock, a new gg&g gas port with sight...
now i need a 10" daniel defense lite rail and a k3x novenske...
damn....i had it in past but i sold....:-( now i need it and i dont find any one want to ship it to me here....
+1 on what Larry said. IMHO, the best way to go about it is to just feel it out. If it was your rifle, taking into context how you run and maintain your gear, does it look and feel like it's only had 200 rounds through it? Look over the exterior, work the CH and trigger. Not a sure way but then again without an accurate and honest shoot log there is no way to tell so falling back to your instincts may be the way to go.
If all good, from there, you can go into details. Go over the receivers, barrel, receiver extension, end plate and castle nut. If it's good, go into the tiny details. The FSB as Larry suggested, under the handguards, the barrel nut area, work the springs on the delta ring. If its rusted inside it should crunch a bit when you work it.
Check the bore and chamber**. Should look practically brandnew if it's only had 200 rounds through it. Check the crown -- as much as you can see with the flash hider on. Check the amount of carbon build up** on it.
The BCG check as Larry also suggested and look at the bolt lugs** in particular. If it's fairly well maintained and well lubed and has only had 200 rounds on it, you shouldnt see too much wear on it. Make sure it's not all shiny and silver as this may indicate more use than advertised or even a bolt swap.
Check the all the receiver pin holes - makes sure theyre not egged out or damanged. Take down and pivot pins and holes should be checked as well.
Finally ask to take it apart. Check the triggers for excessive wear and rust. Check the pins, take out the safety, go over it for rust. The safety detent pin and spring should give a general idea on the condition of the pivot and take down pins detents and springs.
This is purely my personal opinion and at the risk of looking like a product label, I indicated all highly subjective points with **. These things from my little experience and limited knowledge, have many factors ranging from maintenance/cleaning habits, amount of lube applied, type of ammo shot etc... and may or may not indicate heavy use.
This might help, or at least serve as a good starting point.
http://farm5.static.flickr.com/4018/4292000236_d570aeeb07_o.png
thanks guys
i will let u know in a copuple of days if i will have my ny ar15 or not...
I purchased a used AR and there only 2 things that I found that were in need of replacement, the CAM PIN was cracked from impacting the bolt start/stop, it has a "Fishmouth" shaped indention pounded into the side with a crack forming along this indention. I even did a mag particle test after polishing the material smooth with a dremel to see if my visual assessment was correct.... it was.
The only other thing I found was typical... the gas rings were loose as a goose. I purchased some of those spiral rings to replace the 3 individual gas rings, but honestly I have yet to install them because I had a couple sets of standard gas rings left. I put in the standard gas rings and still have the spiral rings waiting.
The cam pin in this bolt was the one with the crack:
http://i409.photobucket.com/albums/pp174/larry0071/Bushmaster%20BCG/38330b1d.jpg
It cracked from the natural cycling of the bolt. The bolt ends it's travel by slamming the side of the cam pin into the radial slot in the bolt carrier.
So between the material of the bolt, the hole that the pin passes through.... and the side of the radial slot in the bolt carrier... you get a sort of sheering effect that eventually abuses the cam pin. The following pictures are of the two holes I just mentioned:
Hole in bolt that CAM PIN goes through:
http://i409.photobucket.com/albums/pp174/larry0071/Bushmaster%20BCG/a22466b1.jpg
And the radial hole (Twists the bolt as it travels) in the Bolt Carrier:
http://i409.photobucket.com/albums/pp174/larry0071/Bushmaster%20BCG/274d934a.jpg
Hopefully yours is like my used one was, and only has minor issues from normal use.
thanks guys
i will look for it
i have not understood how to check the gas rings
i have to put the bolt into the bolt carrier in this way and watch if the bolt fall down ?
http://img3.imageshack.us/img3/5528/p1050157v.jpg (http://img3.imageshack.us/i/p1050157v.jpg/)
guys i need a 10" DD light rail....
anyone have one on sale and want to ship it to me?
i have not understood how to check the gas rings
Scroll down to: GAS RING SERVICEABILITY CHECK
http://www.weaponevolution.com/forum/showthread.php?t=1613
I put the bolt face down and see if the weight of the carrier will slide the carrier down. If so, it gets new rings. I give the old rings to my brother in law, he will keep running them for months! It might be over cautious, but I never have experianced a short stroke or any other gas related issue. I am not a high round count guy, but I like having good days out with my son... not days getting mad that my rifle keeps screwing up!
Basically, exactly what you have pictured, but flip it upside-down. YMMV.
right
i have understood
thanks guys
ok.. i made this test with the bolt i use on my bushmaster....
so... i think i have to change the 3 rings.....
the carrier fall down on the bolt
now.. 2 questions....
how to remove and install the rings..?
and
how long is the life of this rings? how many ammo??
andy
Here is a picture of mine standing tall on the bolt. I just installed a new set of the spiral rings.
You asked how to get the rings off, just kind of get your finger nail to catch the opening and pry out from centerline and get it to move towards the bolt-tail. Once you get that to happen, it is cake work.... just walk it around and it will come right off.
Similar process getting the new on. You have to just work it around, similar to when your changing a tire on your childs bicycle.
Also, I am changing my ARs over to this style gas ring:
http://i409.photobucket.com/albums/pp174/larry0071/AR%20BCG%20Comparison/100_2501.jpg
Also, I am changing my ARs over to this style gas ring:
http://www.brownells.com/.aspx/pid=18722/Product/AR_15_MCFARLAND_trade__BOLT_GAS_RING
AR-15 MCFARLAND™ BOLT GAS RING
Stops Gas Leaks & Eliminates Sluggish Bolt Performance
Single spiral of spring steel loops around the bolt three times and leaves no path for gas leakage. Replaces conventional three-piece “piston ring”-style sets that can accidentally line up, causing a major leak from the gas expansion chamber in the carrier.
http://www.brownells.com/userdocs/products/l_100001257_1.jpg
You simply use a small pick or thin blade and unpeel them from the bolt. Then clean the around the gas rings and install the new ones by peeling them onto the bolt. Start one of them in the groove and just use your fingernails. Much simpler is the McFarland gas ring and they seem to last longer.
There is no standard life for gas rings, which is why you should maintain a round count and periodic inspection.
ok.. i made this test with the bolt i use on my bushmaster....
so... i think i have to change the 3 rings.....
the carrier fall down on the bolt
now.. 2 questions....
how to remove and install the rings..?
and
how long is the life of this rings? how many ammo??
andy
yup
changed the rings yesterday with the Mc farland rings i had here...
now the bolt stand on the carrier....
thanks
this is the new rifle i boguth today
http://img717.imageshack.us/img717/1207/p1050160.jpg (http://img717.imageshack.us/i/p1050160.jpg/)
an oly k3b..made in may '06
and never used...
the bolt is perfect..
only very few scratches on the external of the receiver..
now im try to understood how ro remove the flash hider...
Never used? I thought the seller said he had 200 rounds through it?
Looks much better than I had initially imagined though. Congrats! It's practically brand new. Is that an LMT receiver extension on it? Did that come with it?
As for the few scratches, if it bothers you, get Birchwood Casey's Aluminum Black or Alumahyde. Apply as directed with a Qtip but do not double dip - read this somewhere but makes sense as it would contaminate the rest of the bottle.
Now for the more important part... Is your FH, is it pinned?? If it is, do a quick search on how to remove it. You should find a thread or two on it.
well Crocs
it really now "never used" but is better than i can image...
the bolt and the charging handle have no signs or scratches...
it have few scatches on the receiver only...
it come with A2 stock and i changed it with this vltor
about the FH..
welll..
i wrote a question on 6 forums...lol..
im trying to understood....
cause i really want to remove it as soon as possible and put a new 10" rail and a kx3 novenske....
i bouht it and waiting to receive...
just polished the area near the sign at 2 o'clock...
it may be the pin??
http://img442.imageshack.us/img442/1182/p1050200.jpg (http://img442.imageshack.us/i/p1050200.jpg/)
http://img524.imageshack.us/img524/5007/p1050199q.jpg (http://img524.imageshack.us/i/p1050199q.jpg/)
I agree and it does look practically brand new.
Well, judging from you pic, yes, it does look like a pin. However, please dont take my word for it. This is a rather unusual spot to pin an FH IMHO.
Ask or do research on your rifle and see exactly how (process/type mentioned by GotM4 in your other thread) the manufacturer originally pins these things on and just as important, exactly where.
i did the work..
the pin is exactly on the top of the Fh
put in horizontal
i thought it was in vertical but it is not.
look the red line in this draw
http://img690.imageshack.us/img690/5782/spiun.jpg (http://img690.imageshack.us/i/spiun.jpg/)
and this is the final temporary solution till i will have parts fromusa
http://img33.imageshack.us/img33/8248/99042149.jpg (http://img33.imageshack.us/i/99042149.jpg/)
Glad to see you got if off successfully.
What's that white stuff on the barrel at the base of your Vortex though? Is that tape residue or did you mar the barrel surface?
oh...only permant blue by birchwood casey...to cover a little scratch
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