Quantcast

Home built AR-15 = unreliable?

Discussion in 'Rifle Country' started by Tarvis, Sep 23, 2008.

Thread Status:
Not open for further replies.
  1. Tarvis

    Tarvis Member

    Joined:
    Nov 13, 2007
    Messages:
    1,178
    Location:
    Northern Pennsylvania
    I have read a few different posts on why you should buy a factory gun because it's more reliable and comes with a warranty. Someone had posted that in a carbine class, 100% of the rifles that broke were home builds.

    My question is this: what is it about a home built AR that makes it less reliable? I realize that professionally trained armorers test factory guns and the factory itself has tolerances that are most likely tight enough to keep the gun running, but where, read what part, does that reliability come from? I know first hand that if you do not assemble the lower properly it will fail (hammer springs go over the trigger pin :banghead:). Other than that, it seems the only other part that would cause a home-built to fail would be the BCG.

    I realize many home assembled AR's run flawlessly so I don't need to know how many people haven't had problems. What I want to know is what will cause them to fail under high stress, such as a carbine class.

    For the record, assume the "home built" had the barrel group installed on the receiver by the distributor/manufacturer.

    Edit: also, this thread is for comparison of factory and kit AR-15's using a DI gas system.
     
  2. Avenger29

    Avenger29 Member

    Joined:
    Jun 2, 2005
    Messages:
    2,728
    Location:
    SC
    Maybe it's not the home assembled lowers per say, but that the homebuilder slapped the cheapest upper and BCG they could get their hands on to complete the rifle.

    If the lower is put together correctly, it's put together correctly. Whether it was put together at the kitchen table or the table at the factory, it doesn't matter.
     
  3. iiibdsiil

    iiibdsiil Member

    Joined:
    Sep 20, 2004
    Messages:
    740
    Location:
    910 / 813 / 561
    If you listen to the Colt guys, Colts are the only ones that don't screw up during a course. ;)

    When you build it yourself, assuming you get the parts selection correct, there isn't any reason you would have any more or less problems then anyone else.

    You aren't machining the receiver, you aren't making the barrel, you are putting parts together. Buy the upper pre-assembled and you really can't screw too much up.
     
  4. Tarvis

    Tarvis Member

    Joined:
    Nov 13, 2007
    Messages:
    1,178
    Location:
    Northern Pennsylvania
    A cheap BCG is more prone to failure than a good MPI, shot peened and heat treated BCG, but a cheap upper just means the barrel may not be as accurate, correct?
     
  5. Crunker1337

    Crunker1337 Member

    Joined:
    Apr 12, 2007
    Messages:
    1,168
    I've always thought that home-built ARs (and other guns, for that matter) needed tuning before they could run 100%... but after the tuning, I've never entertained the idea that a custom-built rifle might be WORSE than a factory manufactured one.
     
  6. Shear_stress

    Shear_stress Member

    Joined:
    Apr 27, 2005
    Messages:
    2,728
    I've done three builds and all have been 100% reliable (and this is with Wolf ammo almost exclusively). As the phrase goes, buy quality and you only cry once.
     
  7. Gary G23

    Gary G23 Member

    Joined:
    Jan 1, 2003
    Messages:
    1,451
    Location:
    Corvette City
    I have owned 21 AR's. The last five have been frankenguns. Only the last five have been reliable enough to bet your life on.

    If you use cheap parts you get crap results.
     
  8. Gary G23

    Gary G23 Member

    Joined:
    Jan 1, 2003
    Messages:
    1,451
    Location:
    Corvette City
    "A cheap BCG is more prone to failure than a good MPI, shot peened and heat treated BCG, but a cheap upper just means the barrel may not be as accurate, correct?"

    A tight chamber or one that isn't chrome lined can cause reliability problems.
     
  9. PPGMD

    PPGMD Member

    Joined:
    Mar 20, 2007
    Messages:
    890
    If you build it to Colt specs with quality parts, then it should be reliable. But too many people slap the rifle together. I've seen a couple of rifles where the barrel nut, and flash hider were finger tight.
     
  10. Avenger29

    Avenger29 Member

    Joined:
    Jun 2, 2005
    Messages:
    2,728
    Location:
    SC
    The OP said let's assume that the upper is assembled by a manufacturer.

    That said, there are manufacturers with poor QC or poor parts quality.
     
  11. PPGMD

    PPGMD Member

    Joined:
    Mar 20, 2007
    Messages:
    890
    He asked what is it that makes home built ARs unreliable.

    Factory ARs can have the same problems with poor parts, and poor QC. But most of the issues I've seen from factory ARs are parts related, rarely from being assembled.
     
  12. wideym

    wideym Member

    Joined:
    May 30, 2007
    Messages:
    929
    Location:
    Arkansas
    Just don't call them "Home built", call them "Custom built".
     
  13. 45B@cav

    [email protected] Member

    Joined:
    Aug 9, 2008
    Messages:
    337
    Location:
    Northwestern Missouri
    If you assemble with sub par parts you get a sub par gun.
    Use the best from the best and you can't go wrong. unless you screw up the build, but I don't know how a straight forward build such as the AR could be screwed up.
     
  14. rob_s

    rob_s Member

    Joined:
    Jul 19, 2006
    Messages:
    415
    Location:
    SE FL
    Generally "frankenguns" that don't run, don't run for one, or both, of the following reasons...
    1) Poor quality parts. Often when somebody builds a gun themselves at home they do so because they've been told "you can build a better gun for less". What they miss out on is that this does not mean you can buy better parts for less. Quality costs. If you choose to buy an AR15 BCG from RRA instead of an M16 BCG from LMT or BCM then you're more likely to have problems with the cheaper part.

    2) People don't know what they're doing. Yes, building an AR CAN BE like assembling Legos. But it can also be screwed up. Very few of the guides I've seen, for example, mention staking the receiver endplate to the castle nut. Forget to do this, and eventually that castle nut is backing off, which in turn causes you all sorts of problems. There are several little items like this that a newbie may not know about.

    I have seen frankenguns all but disintegrate, and I have seen them run with the best of the factory guns. The devil is in the details.

    Whether you have a frankengun or a factory gun, you should get at least 500 rounds, and preferably double that, trouble-free through the gun before you go running off to a carbine course with it. I was in one class where a shooter literally pulled the rifle out of the box it came in and shot it (however briefly) at a class without ever having fired it before.
     
  15. rob_s

    rob_s Member

    Joined:
    Jul 19, 2006
    Messages:
    415
    Location:
    SE FL
    Just off the top of my head, mistakes I've seen:
    Failing to stake the carrier key (because they didn't buy a quality BCG to begin with), failing to stake the receiver endplate, failing to screw the magazine release button in far enough, failing to properly install a FF tube, failing to locktite a pistol grip, failing to properly orient the hammer spring...
     
  16. taliv

    taliv Moderator

    Joined:
    Oct 23, 2004
    Messages:
    24,309
    tendencies of home builders that lead to problems:

    > budget parts - it should be obvious, but sadly isn't, that crappy parts will be more likely to fail. dang near every part on any gun is capable of failing. cheaper metal is responsible for parts such as the charging handle bending, or extractor wearing or breaking, or the bolt-catch snapping in two, or springs wearing prematurely or binding so that your bolt release isn't under tension, etc. etc. etc. I find it pretty amusing that the same people who rail against MIM frames in handguns will put no-brand gunshow special lower parts in their ARs. we don't need no stinkin heat treating :rolleyes:

    > expensive parts that are more oriented for varminting or gaming - nothing wrong with them, but generally speaking... accuracy - reliability - cost ... pick any two. things that enhance accuracy frequently reduce reliability. i'm just saying most folks choose accuracy and cost, which gives home-builds a bad reputation for reliability

    > parts from different mfgs - factory gun parts may be non-standard dimensions, but will still fit together because they are spec'd to fit together. when someone takes one of these not-quite-standard parts and puts it with some other mfg's not-quite-standard part, you can have problems.

    >sub-optimal assembly - some people don't seem to care how much torque is applied where, or which parts should get loc-tite and which parts shouldn't. and then the choice of parts plays in here as well... if your super-cool aftermarket barrel doesn't have a slot for pinning a gas block, how many home-builders are going to machine one? or will they just use a gas block that has a couple allen screws? ...that then falls off after a couple mag dumps


    i personally think you can build an awesome gun out of parts at home. mine have been reliable, but all of my builds have cost roughly twice what i could have bought a colt 6920 for. (I don't believe I can build a reliable gun for less than I can buy a CD M4-LE)
     
  17. 30Cal

    30Cal Member

    Joined:
    Feb 11, 2004
    Messages:
    2,350
    Location:
    Albany, NY
    I bought a used Frankengun (a NM configuration) and had to fix some problems created during it's assembly to get it to run.

    The float tube/barrel nut was badly indexed and red loktited in place, causing the gas tube to be poorly aligned with the carrier.

    I also had to cut a fair amount of material from the bolt stop to allow the bolt to fully close reliably.

    Runs just fine now, though.
     
  18. RockyMtnTactical

    RockyMtnTactical Member

    Joined:
    Oct 21, 2006
    Messages:
    3,539
  19. raz-0

    raz-0 Member

    Joined:
    Dec 26, 2002
    Messages:
    789
    Location:
    NJ
    The main issue with home built guns is the builder.

    First problem is being cheap to a fault. You don't need the $300 drop in trigger, but the $5 trigger job that involves cutting off one leg of a spring and polishing stuff isn't a good replacement for it either. Same goes for any other part that is critical for functioning. There's stuff that is a good value, and stuff that is junk. If you go for the absolute lowest price, more often than not you get the junk. If you bought the cheapest parts, are you going to run a case of ammo through it that costs 70% of what you spent on the gun to determine if you did it right? Howabout half a case? Howabout 200 rounds even?

    Second problem is inexperience. So you saved $5 on a gas tube. Was it because the guy selling parts sells it at cost to drive sales of his other, more profitable parts, or because it was out of spec, damaged, etc? Do you know what a healthy one looks like? If it ws healthy, and you didn't get all your bits mounted right, and it is getting only very slightly damaged, do you know what to look for, or what symptoms it causes if it is working it's way out of spec slowly? If the barrel is clocked slightly causing this problem, do you know how to fix it? Do you know what to change (or purchase in the first place) to get your buffer, BCG, and gas tube length chosen to work well together? Do you know how to tell if your mag lips are out of spec, and what problems that will cause?

    The third problem is being too clever/cool for your own good. Sure, you can drop $300 on a lightened BCG, but do you need it given your gas system setup? Do you know why you might need an adjustable gas block? If not, why did you get one, and do you know how to adjust it for reliability. Did you get the super accurate $600 barrel with the tight chamber, but plan on feeding it the cheapeast ammo you can buy because the gun cost so much? You bought the slick competition upper without a forward assist, but plan on taking the thing to school with a 2000 round count, and you will be feeding it cheap ammo to control costs, so you might just need that forward assist.


    Some of these issues, people get into on their own. Some get them by proxy by slapping a cheap upper on a home assembled lower.

    Do lots of research, read up a lot, keep your reference material near at hand when doing the actual work, because your memory always sucks more than you think it does. Don't be stupidly cheap, and don't push the limits of the platform and expect it to be life or death reliable.
     
  20. strat81

    strat81 Member

    Joined:
    Oct 6, 2006
    Messages:
    3,912
    Location:
    Nebraska
    A loose chamber or one that is chrome lined can cause reliability problems too.

    Loose chambers can lead to problems if the case cannot fully seal the chamber. Improper chroming can lead to flaking which can cause extraction issues.

    I also question the OP's mention of "100% of the rifles that broke were home builds." What exactly broke on 100% of these rifles?

    Bolts? Carriers? Triggers? FCG pins? Charging Handles? Front sights? Rear sights? Stocks?

    Was there are a catastrophic barrel failure due to lack of parkerizing under the front sight base?

    Use crappy parts, get crappy results. Assemble quality parts poorly, get poor results.
     
  21. benEzra

    benEzra Moderator Emeritus

    Joined:
    Dec 25, 2002
    Messages:
    8,696
    Location:
    Down East in NC
    Lack of experience; improvised tools and fixtures to save money; and choosing the cheapest-possible parts to save money.

    A homebuilt AR made with top-drawer parts, built with the right tools and fixtures by someone who knows what they're doing, will be as reliable as the same rifle built by anyone. A rifle assembled by a novice with improvised tools and cheap parts, not so much.
     
  22. vanfunk

    vanfunk Member

    Joined:
    Jan 9, 2003
    Messages:
    665
    Location:
    The widening gyre
    I think a great deal has to do with two things: manufacturing standards (of component parts)and tolerance stacking.

    Manufacturing standards: How were the parts assembled, and under whose testing? What standard, if any, were the parts held to? What were the tolerances for acceptance/rejection? That's a big problem in the civilian AR arena, where oftentimes the only "standard" adhered to is that of the marketplace, and, let's face it, that's really not much of a standard. One might assume that if company X is making crappy bolt carrier groups, then people will stop buying them. In actuality, if "crappy" parts can be purchased at a discount, people will buy them and use them.

    Tolerance stacking: ever wonder what happens when you take a part that's .003" too long, and mate it with another part that's .003" out of spec? Well, maybe nothing, or maybe the parts will run without issue for a time at the limit of functionality, and then break.

    Ideally, all manufacturers would follow the technical data package for AR parts, and then we'd see far fewer problems with "Frankenguns" than we do now. Take the M1 carbine for example - you can assemble a carbine (or a Garand, or a 1911A1) with parts made from 11 different (USGI) manufacturers and the darn thing'll work because the parts were made of the right materials, to the right specification. AR parts houses can only dream of that level of interchangeability.

    Using the right materials costs money, correct assembly of parts costs money, checking the parts for material integrity and measurement spec costs money, testing the subassemblies and finished guns costs money. The less of all of those things a company needs to do to bring a product on the civilian market, the more they can sell, assuming some "tolerable" level of functionality. Sadly, the AR market can absorb alot of "crappy" parts. Bushmaster sent thousands of rifles and carbines out the door for years with grossly overtorqued barrels and unstaked carrier keys. They knew there was a problem, and yet did nothing to address it. It was cheaper to let the consumer decide if it was a problem or not, and most didn't care enough to take them to task for shoddy assembly... Many other manufacturers have been equally guilty of similar practices. Fortunately, there are many manufacturers who take their product and their customers seriously enough to make great parts, great assemblies, and great guns. And we all know who they are already...


    vanfunk
     
    Last edited: Sep 26, 2008
  23. Soybomb

    Soybomb Member

    Joined:
    Oct 31, 2005
    Messages:
    3,959
    Anyone that isn't a goober can build a reliable ar15. There are a lot of goobers in the world though.

    If you don't mind I'll make this modification and say these are the problems to me. Earlier this week I saw someone had their bolt catch spring in the disconnector spring position. I see people talking about what doesn't need to be staked or what high temperature area loctite will work just as well in, etc
     
  24. Tarvis

    Tarvis Member

    Joined:
    Nov 13, 2007
    Messages:
    1,178
    Location:
    Northern Pennsylvania
    That is what I was asking. I'm not sure which thread it was, but someone specifically said that in a carbine class he attended, every single one of the non factory guns broke. This may have been an exaggeration, and "break" may have also meant "failed to feed" or something of that manner.

    I hear it over and over and over and over and over that you should use quality parts and not go cheap. So far in this thread, I have seen three, maybe four posters mention what parts will break and a few ideas on what needs loctite and what needs to be staked. It seems that everyone knows good parts are more expensive, but not many have good suggestions on whose LPK to buy.
    I've heard that RRA makes a good BCG, and that the LMT enhanced BCG is overkill from a guy that sells them. I'm not writing this into the Bible, just pointing out a difference in opinion. FWIW, I wanted to buy a BCM BCG but had to settle for a CMT M16 BCG. Someone tell BCM to speed up production.

    Also, thanks for the ideas on assembly. I've heard of staking the castle nut but I hadn't heard it could be a problem part. I also didn't know that the grip screw needs loctite.
    *EEERH* Product testing may be an initial slow down, but in the grand scheme of things it would be scheduled in front of product release. The opportunity cost of testing is retained earnings, not production. You could also argue that it costs even more money when you find a problem, assuming a problem that was found could not be ignored.
    That is a bit presumptuous. Unless I'm playing devil's advocate with a former employee *ducks*.
    That's business. I have the entrepreneur spirit so I may be biased, but I'd sell "custom manufactured air" if I thought someone would buy it ;).


    For the most part, thanks to all for posting thus far. I appreciate the ideas on chamber specs, cost vs accuracy vs reliability, BCG's and assembly thoughts. So what manufacturer makes the best AR?

    Come on, that was a joke :neener:
     
  25. rob_s

    rob_s Member

    Joined:
    Jul 19, 2006
    Messages:
    415
    Location:
    SE FL
    I wouldn't bother with the LMT enhanced either. I'm talking about the $130 standard M16 BCG that they sell.

    I have no use for an AR15 BCG with improperly staked key, non MPI and non HPT bolt, so I have no use for RRA.
     
Thread Status:
Not open for further replies.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice