ESSENTIAL PARTS FOR
The best spare part is a complete bolt carrier assembly. I always carry one to a tournament event. Of course, it’s necessary to test the spare not only for function but also for zero. Notes are made as needed. A complete carrier assembly will more quickly and conveniently replace any part likely to be broken in the course of firing. If not a complete carrier, then a spare bolt, tested and noted as well, saves most days from ending early. A firing pin is easy enough to tote along. I have wrecked those during ammo testing sessions (from pierced primers).
The level of repair you might be capable of effecting out in the field, whichever field it is, is limited to the amount of tools and, of course, parts, you’re willing to tote along in your kit. This piece will focus more on what’s kept back at home.
If you work on AR-15’s much, it’s very likely you’ll lose or damage pins and springs. Some springs in particular are delicate with respect to kinking. Some are also under a lot of pressure, like the ejector spring. I don’t know the physics behind it, but if a careening spring makes more than three “ting” noises before silence refills the work area, that one is gone forever. A strong flashlight is the best tool to help recover them, and pins, from a shop floor.
I keep a roll pin set in good order. For low volume use, one of the pin set kits should be all you need. Gas tube pins especially can be problematic since they are easily and often damaged. The best tip I can give on avoiding damage is to address the tip itself. I always radius and polish both ends of a roll pin before installation. The polish on the “enter” end is a big help to installation, and treating the other end helps with removal. However, when it’s possible, it’s best to drive the pin all the way through to remove it; that way it might be possible to reuse the pin.
I also oil roll pins prior to installation—just a drop on the “in” end. That not only makes installation worlds easier, the film deposited eases the “stiction” that can otherwise occur between steel and aluminum. That makes it easier to remove.
There are a few “supply item” parts on the AR. Usually, nothing gets replaced until/unless it breaks, but it is a wise idea to get on a schedule of routine replacements for a rifle that sees hard use, which is frequent use, high round count, or however else you want to qualify it.
This pin set is quite handy. Glen usually buys them two at
a time so there’s always a spare available.
It might be a more costly solution, but it is a solution. A tested,
complete bolt carrier assembly means an amazingly quick repair to
most anything likely to go wrong with your AR-15 in the field.
Glen does carry spare firing pins. Not this many, but tip damage or
breakage is easily cured with a handy replacement.
If you have read anything I’ve written on this topic, you’ll know I am a believer in chrome silicon springs. They perform better than the common music wire variety, and they last much, much longer. Otherwise, if you are running stock springs, replace them at 2,500-round intervals. The extractor and ejector springs may need more frequent replacement, especially in a full-auto. There’s a lot of heat transferred to these springs, and almost everyone who has fired full-auto for an extended session has reported an extractor spring break. A stock buffer spring is good for a maximum of 5,000 rounds, and I say it needs to be trashcanned in half that time. It’s one source of the “mystery malfunctions” that befall the AR at around a 4,000- to 5,000-round count. It’s also a solution (along with a thorough cleaning of the bolt carrier recess, which houses the tail end of the bolt). The buffer spring just sacks out. If you spend up for the preventative bliss of chrome silicon, you should never need to replace the springs, and they will work at virtually as-new performance levels all along.
Any work done in the field requires a means for cleaning. Take a couple of shop rags and a spritz-type aerosol cleaner to get the grit and grime off any parts you’re working with. A small can of brake cleaner works well—just don’t neglect recoating the parts with a lube. I carry all the tools and spares to the range using a fisherman’s tackle box, which also has my cleaning gear and lubes.
There are bound to be some unusual happenstances that can end a range day early, but if you don’t have the needed tools and work area at hand, sometimes the repair can break more than it fixes. I’ll end this where it started: the best assurance against the radical majority of likely problems is cured by a spare bolt carrier assembly.
Keep an eye on the extractor and ejector springs. Replace or upgrade. Upgrading makes
more sense and requires less work. Most other springs can be ignored immediately after
initial installation. The hammer spring will need attention at some point, too. A better
material won’t, but the stock music wire varieties do lose power over time.
Glen suggests one of two options with buffer springs: either replace a stock
spring every 2,500 rounds or—better—get one of the “lifetime” buffer springs
such as this flatwire from Superior Shooting Systems Inc.
The preceding is a specially adapted excerpt from The Competitive AR15: Ultimate Technical Guide, a book by Glen Zediker and Zediker Publishing. For more information, visit www.zedikerpublishing.com or call (662) 473-6107.
By Glen Zediker
200 South Front St.
Montezuma, IA 50171
Superior Shooting Inc.
800 N. 2nd St.
Canadian, TX 79014