Friday, May 24, 2013

AR-15 Bolt and Carrier Assembly and Maintenance

For someone new to the AR-15 weapon platform, weapon cleaning and the disassembly associated with it can be a little worrisome.  The AR-15 is a battle weapon, and despite all the opinions of the "pro-AK" crowd, it honestly requires very little maintenance and is a very rugged and dependable design.  Normal post-shooting cleaning and maintenance, however, will provide a long and dependable service life of the rifle and its parts.  We have detailed a simple cleaning procedure in a previous blog post, but this one will focus on the bolt and carrier assembly exclusively and in greater detail (rather than the entire weapon overview provided in the earlier post on the subject).

By pushing out the rear takedown pin on the left side of the weapon, the upper receiver of the rifle will pivot on the front takedown pin and allow you access to the charging handle and bolt and carrier assembly for removal.  Pull on the charging handle as you would to chamber a round and the bolt and carrier assembly will slide out of the rear of the upper receiver.

Firing pin retaining pin removal

The first step in disassembly is to remove the firing pin retaining pin; you may be able to do it with your fingernails but if not, a small pointed object like a nail can begin to free it from the carrier. Make sure to set any removed parts aside safely so they do not get lost.  Once the firing pin retaining pin is removed, the firing pin should slide out of the bolt and carrier assembly if it is tipped up.  If it is heavily fouled, you may have to pull it out towards the cut out in the rear portion of the carrier.  The retaining pin may not require much cleaning, but there will likely be a build up of fouling on the firing pin itself, especially in the area where the retaining pin holds it in the bolt.  Heavy build up may require soaking in a solvent, but typically a toothbrush or light wire brush can remove just about any amount of fouling.

Cam pin ready for removal from bolt and carrier
Once the firing pin is removed, the cam pin should be rotated so that it can be removed from the bolt and out of the top of the carrier, right below the carrier key (the bolt must be in its rearmost position to allow you access to remove it).  Light cleaning is also usually all that is necessary for the cam pin.  Once it is removed, the bolt can be pulled out of the front of the carrier.  This completes our suggested disassembly procedure for the bolt and carrier assembly.

For typical maintenance and cleaning, we do not suggest removing the extractor or ejector parts of the bolt.  A dental pick or similar instrument can remove any fouling buildup from right under the extractor claw on the bolt face and a toothbrush and light solvent should be all that is necessary to clean this area of the bolt.  Running the solvent soaked brush over the gas rings on the bolt is a good idea as well, but always make sure the slots in the gas rings are not aligned once you have done this and before inserting the bolt back into the carrier.  Having the gaps in the rings aligned can cause excessive gas leakage to pass by them and affect the cycling of the weapon.  Carbon fouling can really build up on the tail end of the bolt, so special attention should be focused here.  A light coat of oil on the bolt (except for the bolt face) should be the last step in maintenance before reassembly.  The internal areas of the carrier may require solvent and brushing to remove carbon fouling.  Any weapons cleaning product purchased at a sporting goods retailer can accomplish this, though most people have their favorite brands.  In our earlier blog post on cleaning the AR-15, we provided the names of a few of the most popular brands and their benefits.

Insert the bolt back into the front of the carrier, making sure the cam pin hole in the bolt is properly oriented for the cam pin slot in the carrier.  If you look at the bolt face "head on" the extractor should be at the 11 o'clock position.  The cam pin will only go into one side of the bolt, so if it is not fitting, check and make sure the bolt and extractor are oriented as stated  above.  Once the cam pin is inserted into the carrier and bolt, the firing pin can be inserted into the tail of the bolt from the cutout in the back of the carrier.  The cam pin must be oriented perpendicular (in length) rather than parallel to allow the firing pin to be inserted all the way.  Now that the firing pin is in, the last step will be to put the firing pin retaining pin back in to hold the firing pin inside the bolt.  Pull and push on the bolt (imitating the cycling of the weapon) to make sure the entire assembly is correctly assembled.

Fouling build up in the barrel, chamber, barrel extension, and bolt and carrier assembly can cause malfunctions and decrease the productive lifespan of your weapon.  It is best to clean these areas thoroughly as soon as possible after a typical shooting session.  It can seem difficult to new owners and time consuming to all to pay attention to and disassemble all of these parts...after doing it a time or two, you will find you have become more proficient and knowledgeable about the key components of this weapon system and how it operates.  Here is a link to our website with a diagram of the bolt and carrier parts: boltandcarrierparts.

Thanks for reading our blog. If you have any questions about bolt and carrier assembly or maintenance or about the rifles we produce and parts we sell at, please contact us.

1 comment:

  1. Thanks for sharing.I found a lot of interesting information here. A really good post, very thankful and hopeful that you will write many more posts like this one.