First of all, I live in Europe so no US laws apply here (no-one needs to warn about bubba and atf agents). I Just got myself a Bushmaster AR15 carbine 11.5" A2, to my knowledge a unusual weapon here. It's a full auto model (using a DIAS and M16 parts/bolt) almost new, only fired 2-300 rounds, and it's a very cool weapon to shoot with :)

Since I'm new to the AR15/M16 rifle I was wondering what spare parts I should stock up on - as I've heard that parts have a tendency to break after a bit of rough handling.

The goverment here is also considering an assault weapons ban (banning all new assault weapons) - and it will probably come in to effect january next year - which means that new spare parts wil almost be impossible to get a hold of at resonable prices - so i'm thinking about stocking up parts for a long time - and don't have much time to buy them (prices are already increasing because a ban is very likely to come)

I've already bough a fair number of 30rd magazines, so it's primarily the internals I worry about.

Bushmaster sells field repair kits that have a variety of "nice to have" spare parts. Also look for some "spring and pin" kits. I get a couple of extra extractors as well. That way you are sure to never need one. I've only broken one so I bought some extra's. That was 13 years ago and I've never broken another.

Extractor
2 or more extractor springs
Extractor pin
Front & rear takedown pins
Takedown pin detent pins & springs
Hammer
Trigger
Disconnector
Auto-sear
Set of springs
Hammer/trigger pins
(might as well just buy a whole lower receiver parts set)
Gas tube and pin
Gas rings for bolt, at least one set of 3
Ejector, spring and pin
Bolt carrier gas key and bolts
Barrel, a spare might be worth buying?

Off the top of my head, barrels are export restricted "Munitions List" parts, not sure about any others.  So you may have to find a dealer willing to handle State Department paperwork if you want to buy directly from a US source.  I think Bushmaster will do the paperwork, for one.

Most of the above list is a "worst case scenario" list.  At one time I was responsible for maintaining close to 300 M16s, all in excess of 25 years old, and besides the rough/careless-handling damage to stocks the biggest problems I had were with takedown pins (the detents mostly), gas rings and extractors.

The AR15 is fairly durable.  Don't try to use the stock for a hammer to drive tent pegs, or the side of the rifle as a step for 100kg soldiers, and you're not likely to break anything.  I saw more damage from over-cleaning than parts actually wearing out from the rifles being shot.

What country do you live in?  

Thanks for the answers and the "official" welcome

sorry for making a "suspicious" post, i've been browsing the AR15.com page for some days and see plenty of warnings regarding the issue of DIAS, LightningLinks and barrels that aren't 16" - so i wanted to be consise.

I was thinking of buying a barrel from bushmaster, but it requires a lot of paperwork - so If I buy one it will probably be one from a local gunstore (they don't have bushmasters, but some other brand I don't recall at the moment.. maybe "wilson" or something)
Anyway, I understood that chrome lined was the way to go, right?

The barrrel in my bushmaster is a HBar 1/9 - any thought on how many bullets I can put through It before performance starts to degrade seriously? (maybe I'll put aside the barrel investment for now, as I don't have too much cash..  well, who has when you are a hobby shooter.. hat
Chedderby - I live in Latvia

Welcome also from non U.S. member of the AR cult.

Quoted: Thanks for the answers and the "official" welcome sorry for making a "suspicious" post, i've been browsing the AR15.com page for some days and see plenty of warnings regarding the issue of DIAS, LightningLinks and barrels that aren't 16" - so i wanted to be consise.

Forget those DIAS´s and Lightning Links if you already have full auto parts on your lower receiver. Take them off and treat them like they are last ones in the world if you are not able to easily get new ones. Replace them with new semi auto parts and learn to shoot with accurate semi auto fire (if you don´t already do). Well placed single shot is better than 30 misses, IMO.

I was thinking of buying a barrel from bushmaster, but it requires a lot of paperwork - so If I buy one it will probably be one from a local gunstore (they don't have bushmasters, but some other brand I don't recall at the moment.. maybe "wilson" or something) Anyway, I understood that chrome lined was the way to go, right?

You are right on track. Try to get Bushmaster, Colt (1/7"), CMMG (DPMS) or LMT barrels. These are all chrome lined. It is hard way through State Department but it is worth it, you get barrel that serves you many years.
Wilson barrel are good but usually chambered for the .223 Remington and they are not very reliable with military surplus ammunition due their higher pressures. Wilson barrels good for reloaders and targetshooters, IMO.

The barrrel in my bushmaster is a HBar 1/9 - any thought on how many bullets I can put through It before performance starts to degrade seriously? (maybe I'll put aside the barrel investment for now, as I don't have too much cash..  well, who has when you are a hobby shooter..

I have reached 6500+ rounds mark with my M4 barrel and it still shoots well under MOA (about 30 mm @ 100 meters) so you can shoot the hell out of your 11.5" barrel before you see any signs of accuracy loss. I´m recommend you to focus on parts listed on AGCs post above.

Great list AGC, and I'm especially interested in notes on what parts that most frequently fail/break. Of course there's a difference between rough battle handling from GI's and a hobby shooter when it comes to taking care of a rifle.

AGCs list is very good but I´d like to add bufferspring and H buffer to it.

As a sidenote, I have changed only bufferspring to my M4 after those 6500+ rounds, which includes various brands of surplus ammo (PMP, IMI, RORG, RUAG) and pretty hot reloads without single problem.
Bufferspring I changed was still in specs but Bushmaster tech recommended to change it after 6- 8000 rounds and price of that spring is around $3- 5 so it won´t be a problem.

Where did you buy your Bushy, BTW?

MN

As far as full auto parts go for the M16/AR15 system, the one part I have seen most breakage in was the M16 Disconnector. This almost invariably occurred from people using a soft aftermarket disconnector and then breaking open (or was it closing it? Been many years since my full auto days) the rifle with the selector switch still set at full. Never had a problem with Colt M16 disconnectors and if you can get them, I suggest buying a couple - should last a lifetime. Not sure of the quality of BM M16 parts at this point in time, but suspect they are on par with Colt's now. Maybe someone else can jump in here.

Kevin