Given a M4gery, what spare parts, given normal wear and tear, should I keep on hand? I am thinking about operator level repairs/part replacement and parts that are likely to wear out and fail under normal (range) usage. So no armorer’s work like barrel replacement or any thing that would require special tools. By way of example something like spare gas rings. I see a lot of lists but they seem to list parts that the average use would never replace and/or unlikely to break. So what I am asking is what is a realistic list.
I have a feeling many will say a spare bolt. Good idea. Or if you can swing it, even a complete spare BCG. You can load up on the small spare parts from Bravo Company for fairly cheap. gas rings, cam pin, firing pin, firing pin retaining pin, sopmod bolt upgrade/rebuild kit. You don’t need special tools for any of that. Just a punch or even a smaller size allen wrench to push the pin out for the extractor swap.
I would also add an action spring or two. For the basic milspec ones from Bravo Company they are around $5 a piece.
I would keep gas rings, firing pin retaining pin, extractor w/spring, buffer spring.
That and a bolt is pretty good.
Hammer and trigger pins too.
But how often do hammers and trigger pins break? I can see loosing them if you disassemble the lower but how often do you need to do that even to clean it? In the Army the operator was never authorized to do that. I can see having replacement parts for field stripped items that you might drop and loose.
Here is a comprehensive spare parts kit at a fair price.
I’ve broke two over the years. When they shit the bed, your SOL unless you have a spare.
Springs-
-Extractor spring
-Hammer spring
-Action spring
Because They Get Lost Or Damaged-
-Take down pin retainer & spring
-Selector switch retainer & spring
-Buffer retainer & spring
-Bolt cam pin
Parts & Assemblies-
-Complete BCG
-Muzzle device shims
Agreed. All of the small parts on the BCG, a bolt itself, and buffer/action spring. If the other parts are quality and you’re not screwing around with them, you likely wouldn’t need anything else.
ETA - small parts from an LPK would be a good idea too.
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I think that if you are going to be realistic about it you have to assess the rounds you are going to put through your rifle. Another consideration is whether or not you have more than one rifle, and your pressing need to have all rifles ‘up.’
You can’t predict when each part is going to fail.
I guess it also depends on how much money you want to tie up in parts that will likely just sit in a box.
Most AR users will never break a bolt, never run gas rings through their life cycle, heck, never need to replace a buffer spring.
Myself, I’d focus on getting another rifle before getting anything beyond a spare bolt and buffer/action spring. The way bolts are priced in comparison to perfectly serviceable mil-spec BCG’s I’d probably just get a spare BCG and buffer spring.
Keep a spare BCG on hand, especially when you are at the range. Having a box of parts and tools at home isn’t going to do you a lot of good.
The only parts I’ve seen fail regularly outside of the BCG would be the forward assist and the disconnector. The first can be fixed with an upper that doesn’t have one, the second is a little more involved and takes tools.
ETA: The issues I’ve seen in the BCG include worn gas rings, broken bolts at the cam pin, and gas keys striking the gas tube.
The complete BCG is an added, and likely unnecessary, expense. If the gas key staking is good, the chances of the carrier itself failing are pretty low but having a complete one will add almost $100 to the price.
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I agree. This reminds me of the panic days where guys were stashing BCGs 4 and 5 deep. :fie:
I’ve got 4 spare complete BCGs(2xColt and 2xFN). They cost me like $125 a piece. $125 for a quality BCG is pretty cheap in my eyes especially when I have 10+ uppers. Now is the time to stock up. Just my 2 pennies
I agree, just bought 4 spare complete Colt bolt assemblies, already had two complete Colt BCG plus multiple rebuild kits. Probably going to pick up a 100 mags too
I shoot every weekend, but don’t really put enough wear and tear on any one gun to worry too much about a BCG going out. I might have 1 extra pieced together BCG for 8 rifles. Whatever people want to have on hand is cool. I’ve just come to find over the years that extra BCGs aren’t needed.
Seth8, how can the disconnecter and forward assist fail? I know that anything mechanical can fail, but it seems to me that the mean rounds between failure must be very high for those parts. Does anyone know of a chart that lists the MRBF for the various parts?
I read of one failing once and the pawl pushed into the carrier locking the gun up. Winning the powerball is monumentally more likely.
I agree. I have BCG’s because I build these things pretty regularly, never bought a bolt as a standalone part.
A quick look at Brownell’s revealed bolts from 38.00 to 126.00; BCM mil-spec for 80.00; Sionics mil-spec for 70.00.
You can pick up a PSA mil-spec BCG (C-158, HPI, MPI) for 69.99; a Toolcraft BCG (9310 steel) for 68.00 or a Toolcraft 1B1B6 mil-spec for $90.00 at WCArmory.
In reality, it is cheaper to buy just the bolt, but I don’t.