Daniel Defense MK18 Replacement Parts Schedule

The civilian gun industry can be called the Wild West when it comes to specs on various AR components. There are no rules due to many of these companies not holding binding contracts. There are no verifications due to many consumers not having the knowledge nor the tools to check those specifications. While some companies uphold the correct specifications on their parts, some do not. Then comes tolerance stacking, parts wearing out, etc.

Due to these specifications being all over the place, parts need to be replaced in different intervals. The Colt M4/M16 platform is the most looked at as far as "the standard" due to their technical data package (TDP) being over 40 years old, the Army buying that TDP, and their parts holding true in even the harshest conditions. Many consumers will follow Colt’s or the Army’s replacement schedule for most AR parts even if it is from a different company.

Most companies also do not even push out a replacement schedule. While the Colt M4/M16 platform is known as being the long-standing standard, the Daniel Defense MK18 is fast becoming known to keep that standard. The MK18 is ran by many special Army, Air Force, Navy, and Marine units. Larger entities run it as well such as the Department of State and large Department of Defense units. Both of these companies, Colt and Daniel Defense, have pushed out a replacement schedule for various AR parts.

These schedules are meant to catch the part before it fails. It is maintaining the gun so you don’t get to the point of malfunctions or safety issues. Sometimes these parts are to be replaced at a certain round count, or other ways of checking/failing it such as measurements or failure. These part schedules will vary widely on speed of firing, cleaning cycles, ammunition, etc. Round count schedules and annual checks have been what most military and federal agencies have adopted.

Annual checks of all of these parts will usually show the parts needing replacements. Replacement Schedule Let’s go over the main parts that will need replacements and their schedule. Gas rings area common part that comes up when talking about replacements within an AR. Whether you believe that these are as important as put on or not, Daniel Defense states to replace gas rings in 5,000 round intervals. The bolt/gas rings can be checked before the 5,000 round mark in two ways.

One, strip the bolt carrier group, then put the bolt into the carrier and hold upside down. If the bolt stays put under its own weight your rings are still working as prescribed. Another way without stripping the carrier is to push the bolt to the unlocked mode within the carrier then flip upside down and stand on a table, bolt face to table. If the carrier does

not fall, the rings are still making a proper seal. The firing pin problem areas will be the tip of the firing pin; i.e., protrusion. This can be checked with a gauge if you have one rather than around interval. The round interval replacement standard is 5,000 rounds. With a gauge you will have a max and minimum limit. When replacing the firing pin or the bolt, the firing pin protrusion should always be checked with that matched bolt due to bolt face wear.

The action/buffer spring will wear just like any other spring. Daniel Defense states to check the length after 5,000 rounds. The full length of the spring should NOT be shorter than 10.25". Therefore, a minimum length of 10.25". Do not stretch the spring to get it to that minimum length. This will only make it weaker; just replace it if it is short. After a 5,000 round check it should then be checked every 1,000 rounds or annually, whichever is more prevalent.

The bolt cam pin should be replaced every 10,000 rounds as stated by Daniel Defense. To check this before 10,000 rounds, check for material to start rising.

Normal wear marks on the cam pin are normal, however, if you drag your fingernail on the cam pin and feel that mate- Daniel Defense MK18 Lower Receiver: Mil-Spec with Enhanced Flared Magazine Well and Rear Receiver QD Swivel Attachment Point Upper Receiver: Mil-Spec with Indexing Marks and M4 Feed Ramps Barrel: Chrome Moly Vanadium Steel, Cold Hammer Forged, 1:7 Twist, 10.3" Government Profile, Carbine Gas System, Chrome Lined, MP Tested, Mil-Spec Heavy Phosphate Chamber: 5.56 NATO Gas block: Daniel Defense MK12 Flash hider: Daniel Defense Flash Suppressor (1.875") Bolt carrier group: Mil-Spec MP Tested, Properly Staked Gas Key Buffer: H Buffer Sights: Sold Separately Handguard:Daniel Defense RIS II MK18 (Flat Dark Earth or Black) Buttstock: Magpul MOE Buttstock & Mil-Spec Receiver Extension Magazine: Magpul 30-round PMAG Weight: 5.71 pounds Length: 26 3/4" (Collapsed) rial, go ahead and replace.

Cam pins have been known to break due to consistent force back and forth as the firearm cycles. The bolt assembly in its entirety should be replaced every 10,000 rounds, as stated by Daniel Defense. This is for multiple reasons such as a worn bolt face, worn ejector/ejector spring, ejector possibly having debris in the channels, gas rings, extractor lip being worn down, extractor spring and buffer being worn, the lugs being worn/hairline cracks that aren’t seen by operator.

All of these things go into your firearm cycling correctly and much can be missed when just looking at the bolt with the naked eye. Remember, if replacing the bolt only, your barrel has worn with that bolt. When installing anew bolt the best practice is to throw a headspace gauge in and ensure that the headspace gauge passes. The gas tube should be replaced every 10,000 rounds. When thinking of this replacement schedule also be thinking about the barrel due to the gas port.

If the gas tube is wearing down, eroding, or letting extra gas run off, the barrel could be doing the same thing. This can cause malfunctions, however, before that this can be seen by looking around the gas block. If you see gas American Gunsmith Reader Services 1.

If metal is raised on that wear line it is time to replace the pin to prevent total failure. This can help find ejector issues before a malfunction. The ejector should be just about flush with the first edge of that ridge right before the lugs. The wear patterns shown are normal. run off/leakage from the outside of the block, it is probably time to replace the barrel. Also, if you have a borescope, when looking at the gas port you will see long black streaks that look pitted.

If the streak extends and spreads out for an abnormally long length throughout the barrel, that is gas leakage/port erosion and it is time to replace the barrel. Daniel Defense states to replace the hammer and trigger springs at 10,000 rounds. Having worn springs Far On the right side of the port you see some carbon fouling.

If that black portion shown begins to elongate and become pitted, that can be from too much gas leakage and the barrel will need to be replaced. within the trigger group could allow which can be dangerous. Worn disconnect springs can also lead to hammer follow. This issue was seen on old M16A2 rifles; when going to reset the hammer wouldn’t catch, causing the gun to fire. This article was not at all intended to be a "go out and buy a Daniel Defense MK18" advertisement.

It merely demonstrates that they want your firearm to run efficiently and that they will openly share their knowledge to do that. If you follow these replacement schedules you can also use that as additional information if another malfunction is seen when talking to Daniel Defense or other manufacturer. Mind you, they have a full warranty on their firearms no matter the issue.

Keeping up on the maintenance on these seemingly small parts will only aid in not having to replace the much larger and more expensive pieces of your firearm. More importantly, they will ensure that you don’t see malfunctions due to something that could have been prevented. AG