Solutions for AR Rifle Upgrade Problems
The main advantage of the AR10/15 is their adaptability, and the ease with which you can update and customize them. Unfortunately, that can also be their major weakness, as the sheer range of aftermarket parts can mean that sometimes you end up with a bit that doesn’t fit properly. What are the major areas where you can get it wrong, and what should you do about it if you end up in an unfortunate situation?
Many of the common problems found with upgrading your AR stem from not knowing what you have in the first place and getting it wrong when you come to replace it. A good example of this is the trigger group and the pins that secure them. In the Mil-Spec model, these are usually 0.154″ diameter, but in the Colt brand of AR, these pins measure 0.170 “in diameter. Get the wrong sort and your trigger group isn’t either going in or will be loose. For goodness sake, when you are ordering new or replacement parts, be sure of what you have in the first place.
These are quite notorious in their fitting and you need to be extra careful as there is a good deal of compatibility between systems on the market, but also some notable differences. Many of the rail systems on the market have proprietary barrel nuts and these might not be compatible with the Mil Spec standard nut. Once again, check before you buy, or you could end up cross-threaded.
It might seem a fairly innocuous part of your AR, your pistol grip can be a bit of a problem, specifically with the detent – the small, spring-loaded pin that fixes the system in any of its pre-determined positions. Issues arise when you change your pistol grip – typically one of the first parts to get swapped out – and the detent is either missing or incompatible with the locating features on the rifle. This can lead to all sorts of pain and can be potentially dangerous if your pistol grip can move. It’s also worth noting that you need to keep a good eye on your detent if you remove your pistol grip to change other parts; they are very small and can disappear with ease. If removing the pistol grip, lay the lower receiver assembly on a soft surface to help catch it and keep it from rolling away.
If you happen to be one of the folks who prefer the AR’s direct impingement method rather than the gas piston then you’ll find that there is a price to pay. While the original AR design included gas impingement, things have moved on. With the gas impingement method, propellant gas is bled through a small hole located in the barrel, which is then channeled through a small tube where it can proceed to directly contact the bolt carrier mechanism and effectively reload the system. By this method, the gas is pushed to the rear of the rifle, and the spent case is extracted and ejected. The sprung bolt then pushes forward and selects another round. Gas tubes are great but the much easier gas-piston technology has overtaken it somewhat.
If you are still using the direct impingement method on your AR, you may find that the actual tube can come in for some damage after a lot of rounds and small crack can appear. If this happens, then you leak gas and the system doesn’t work so well. Time for a new gas tube, but this can be a bit of an issue. Rifle-size gas tubes are manufactured in three different lengths:
The pistol-length gas system is used almost exclusively on AR pistols or rifles that have very short barrels, usually 10″ in length or less.
The carbine-length gas system, combined with barrel lengths from approximately 10”-18”, is perhaps one of the most common setups across all types of AR rifles.
The mid-length gas systems are becoming increasingly popular, and are usually used with barrels between 14”-20” in length. They tend to give the shooter a longer sight radius and reduce some of the wear and tear on the upper receiver. Mid-length gas tubes are approximately 9.5” and require a handguard around 8.5”-9” in length to accommodate them.
These gas tubes are generally about 13” long, requiring handguards ranging from 11.5”-12” long. These are usually found on rifles with barrels 20” in length and longer.
You can normally estimate what length gas tub that you have by measuring the handguards, but it’s always best to actually get the tube out – if it’s cracked, it’s going to have to come out anyway – and check the length before purchasing a new one.
Muzzle Device Replacement
Just as manufacturers will produce the same type of components to fit Commercial and Mil-Spec tubes, they usually will also make a single model of muzzle accessory, such as a flash hider or muzzle brake in two distinct sizes. One will be sized for AR-15 platforms chambered in 5.56/.223 while the other is made to fit AR-10 platforms chambered for 7.62/.308. As you may expect from such manufacturers, these devices are not interchangeable so you have to know what your size and thread rate is before getting replacements.
Hand Guard Rail Slots
Changing your hand guards is all the rage, and there are plenty on the market, but a little care needs to be taken when swapping these out. There are several different attachment systems in use which are not compatible with each other. Some accessory attachment systems are in general use by several companies, like the KeyMod system which employs keyhole shaped cut-outs, while other rails are entirely proprietary. Check what you need before buying something new.