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View Full Version : Need Advice: Critical Replacement Parts to Stock Up on or Have for An AR-15?


Rock_Islander
04-07-2011, 8:33 AM
I'm going to make a decent sized purchase sometime soon, and it's going to include various parts that I may need to have in order to maintain the function, reliability, and safe-operation of my AR's...

Here's what I can think up of off the top of my head and possibly some of you more knowledgeable guys out there can help me in the right direction if I'm wrong or add as you see fit:

1. Bolt - I see a lot of guys here recommend a new bolt at 10,000 rounds on average. It's largely due to wear and proper headspacing which can result in a kaboom from a worn bolt.

2. Gas Rings - Apparently a "regularly" replaced item as well, however how often do these really need to be changed?

3. Extractors - Has anyone really had an extractor go bad on them? Is it something to keep on hand???

4. AR-15 Field Repair Kit - Various items that include's the above three items mentioned usually, just spare parts to fix whatever may be wrong with your rifle in the field. Necessary or just another useless "kit" ??

5. Gas Tube - Does it ever really need to be replaced?

SOOOO, that's what I have so far. It's a short list but that's all I can think of (besides the barrel) that may wear out - in which I would need spare parts on hand for.

Please chime in and help a Calgunner out!

JDW67
04-07-2011, 8:34 AM
About 10,000 rounds through my RRA and the only thing I've replaced is the gas tube. My bolt still looks brand new...

C_1
04-07-2011, 8:57 AM
An extra lower parts kit, and/or field kit, is a good idea. Make sure to have the extra parts or an upgrade kit for the bolt like extractors, springs, gas rings, and what not. Keeping an extra bolt is not a bad idea either. Gas tubes usually dont go out for a while, but high volume shooting could hurt it a bit, so you could keep a spare if you want. Another part to stock up on are buffer/action springs. They wear out so keep a few on hand. Also, lots of oil!

JDW67
04-07-2011, 9:04 AM
I have enough spare parts to build another AR, but in the 10+ years I've had them, the only thing I used was the gas tube. And I didn't think that was even needed as the old gas tube just needed to be cleaned out.

evidens83
04-07-2011, 9:04 AM
DPMS Ultimate Repair Kit (http://www.midwayusa.com/viewproduct/?productnumber=587468&cm_mmc=Froogle-_-Gunsmithing%20-%20AR-15%20Parts%20(Not%20Magazines)-_-PriceCompListing-_-587468)
BCM Extractor Spring upgrade (http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20%203pack.htm)

Rock_Islander
04-07-2011, 9:48 AM
Thanks for the input so far guys!

dieselpower
04-07-2011, 9:56 AM
If you are looking for a storage of parts to keep your AR running for a long time, here is what I recommend.

1) one or more LPKs (- the grips). You are looking at over 30 years @ normal civilian use on all parts. The hammer, trigger, disconnecter springs are the first to go, but with 2 replacement springs on hand @ 5,000 - 10,000+ shots each, you could easily die of old age before replacing that last spring.

2) one or two COMPLETE Bolts. Bolts take a beating. I don't care if it says MP/HT on it. The chance it will crack in half is only diminished by testing, NOT ELIMINATED. By complete, I mean, gas rings and extractors and ejectors. Two schools of thought on keeping extra Bolt assemblies. One side says keep the spare in the safe till needed, the other side says swap the bolt every time you go out. Side "A" says its bad to swap Bolts because the bolt lugs and chamber lugs wear each other a certain way. Swapping a Bolt will wear in a different way causing a potential problem. Side "B" say by using and alternating Bolts the wear pattern stays close on all bolts. Together both (or all 3) they will find a happy medium. With 2 extra bolts, not only can you keep the gun running for many many years, if one acts up you can swap it out and take it out of rotation until you fix it.

3) Three or Four extra buffer springs. Even well made Mil-spec buffer springs go bad. They are cheap for a reason.

4) An extra Barrel. If you swap your old barrel before its completely dead, you can sell it without feeling like you are ripping someone off. Take a piece of paper and wrap it around the spare barrel. On it write the number of rounds you just shot out of the active barrel. When it reaches a golden number, swap the barrels and sell the old one. Use the cash to help fund a new replacement barrel. Depending on what you use your AR for would depend what your golden number round count will be.

High Accuracy, maybe 5,000. This barrel is still very new, by most peoples standards, sell at like 75% retail cost.
if you are constantly bumpfiring, maybe 10,000. You are beating the heck out of it, so sell at 60% at most.
Heavy shooting like 500 - 1000 rounds down the pipe every month = 10,000 rds. Swap the barrel yearly. Sell at 50%.
Medium shooting like 500 - 1000 rounds every FEW months, 15,000 rounds. So every two years. Sell at 50%.
Light shooting like 500 - 1000 rounds every 6 months, 20,000 rounds. You are looking at a 5 to 10 year barrel life AND still have a good barrel to sell. Sell at 50%.

Swapping the barrel and selling the old barrel as "used, but in serviceable shape" for 50% to 70% of the cost of a new barrel is fair.

If you are putting less than 2000 rounds down range a year don't waste money on an extra barrel. One extra LPK and one extra Bolt will last your lifetime.

Total cost to keep your AR running for your lifetime...
Two LPKs = $120 (you can cut this down by buying the field kits both spring Kits and pin kits)
Two Bolts = $100
Four Buffer springs = $50
One extra barrel = $250
$550ish

CHS
04-07-2011, 10:56 AM
Absolute bare minimum: CMMG Field repair kit. Has all the springs, gas rings, etc that you need.

Bare minimum + some extra cash laying around: The above, plus a bolt (complete HP/MPI'ed bolt. No need for a carrier)

Splurging: The above, plus a spare LPK (try the JP ent. that comes minus pistol grip), and spare recoil spring (buffer spring).

The gas tube will almost never need to be replaced on even very high round count guns. The only times I've ever had to replace gas tubes for people were when their barrel nut wasn't torqued properly, and was just a slight fraction of a degree off of vertical. In this scenario the gas tube gets canted slightly to one direction inside the upper receiver, and the gas key causes enough wear to the "mushroom tip" after a few thousand rounds that you lose gas pressure and start running into function problems. In this case you don't want to just replace the gas tube, because it will keep happening, instead you need to pull the barrel and re-adjust the barrel nut and THEN replace the gas tube.

Rock_Islander
04-07-2011, 12:37 PM
Wow thanks for the really really complete responses I was looking for Dieselpower and Mr. Moderator!

Exactly the type of responses I was looking for. I probably shoot less than 2000 rounds in a year because I just can't afford to lay too much money down on ammo. But an extra complete bolt, field repair kit (or LPK), and buffer springs will be added to my next online purchase.

Thanks a lot guys, everyone else who chimed in as well.

Rock_Islander
04-07-2011, 12:39 PM
But a quick question, at what round count SHOULD a carbine buffer spring (or A2 one) be changed out?

gun toting monkeyboy
04-07-2011, 12:50 PM
make sure you have an extra firing pin retaining pin and a firing pin. In addition to the other parts mentioned. The main parts that I have heard people having problems with were the bolt, extractor, and firing pin. I have never had any problems, but I have a few extras around just in case. Having some extra detents, springs and other odds and ends doesn't hurt either.

Knife Edge
04-07-2011, 2:25 PM
Wow thanks for the really really complete responses I was looking for Dieselpower and Mr. Moderator!

Exactly the type of responses I was looking for. I probably shoot less than 2000 rounds in a year because I just can't afford to lay too much money down on ammo. But an extra complete bolt, field repair kit (or LPK), and buffer springs will be added to my next online purchase.

Thanks a lot guys, everyone else who chimed in as well.

Those dudes know their shiite!