Precautionary maintenance on sub-par guns

[Mike G]

This is something I posted to FB group and was asked to post on the forum. I am posting here and not the workbench since I think the exposure will be greater for those who may not know they have a problem...yet.

What can an armorer or individual do to a gun to make it more reliable if they are issued or stuck with a sub-standard rifle?

Depending on the leeway I have my list:
-Run a set of gauges in the chamber to confirm safe headspace.
-Confirm torque on receiver extension castle nut and stake in place.
-Stake bolt carrier key. I like the MOACKS II.
-Replace the FCG with ALG.
-Confirm torque spec on barrel nut.
-Confirm weight of buffer (there truly is only one or two places that make the standard buffers, if it weighs correctly and visually looks right you should likely be safe).
-Install extractor upgrade kit or replace bolt assembly all together depending on how concerning the original source is. Bolt carriers have larger bearing surfaces and lower failure rates than bolts so even a slightly sub-par bolt carrier will likely hold up much longer than a sub-par bolt.
-Lube, clean, testfire, zero.

All of these represent failures that I have seen on guns that were either built sub-par or abused.

An item that was mentioned that wasn't on my list is the Michiguns 5.56 chamber/throat reamer. I have no first hand experience with this but they get high praise from those that do. The reamer will correct .223 chambers to 5.56 spec so that the gun is not limited to commercial .223 ammo and can reliably shoot the higher pressure 5.56 ammo. These are a little pricey but if you are stuck with a gun that isn't reliable with the ammo you might have to use it is worth the money.

I will try to follow up with a break down on performing these steps and what tools are necessary to accomplish them.

 

[Chris Taylor]

If you just have one personal gun to do, it may be beneficial to just send the upper to Michiguns and have them ream the chamber.

Did it for a friend, turn around was quick, and the price was right. Good folks as well.

 

[LegionPrime]

Well since I'm on here now I guess I'll add here as well for posture . . . or something like that.
You already talked about reaming the chamber, I'd also check the FSB height. If you have a flat top upper and the FSB is not the taller F marked FSB height for flat top uppers you can compensate by swapping in one of the taller then spec front sight posts that replaces the stock post in the FSB.

 

[Bourneshooter]

I was checking staking on the BCG, SOPMOD kit on the Bolt (indicator that it was MP tested as well), stacking on castle nut, barrel chamber markings - depending on manufacture of the barrel is if I trusted it or not - and then lubing.

Our work rifles are all factory purchases Colt's, with after purchase installed DD 12.0 FSP Lite rails. For those rifles the only things I'm checking are for abnormal wear on the Chargin Handle, proper lube, etc. The lack of proper lubrication is the #1 issue I have with our guys.

 

[Matt Landfair]

Stickied

 

[barry.peterson]

That ALG trigger is about the best $65 upgrade you can do. In my opinion.

Good thread; tracking.

 

[Chuck Haggard]

I was issued a 14.5 Bushampster that was't running right, nor would the irons zero due to fucktardery, I had to add the correct front sight post, stake the castle nut to keep the stock from coming loose, ream the chamber to 5.56, and drop in a Colt BCG, it ran like a champ after that.

 

[DreadPirateBob]

When you have said sub-par gun, with a Gas key that needs staking, do you replace screws? Where do you obtain these screws? Is there an approved list?

 

[Wayne Dobbs]

You should include gauging the chamber with an M-Guns NATO chamber gauge and if indicated, reaming with their NATO chamber reamer. It's been my experience with a couple thousand low tier guns that while they have a 5.56 NATO rollmark on the barrel, hardly any have a NATO chamber. Bushmaster is the biggest culprit in this scam I've seen.

Your list is pretty good. What I repeatedly see on these guns are: carbine buffer instead of H buffer; unstaked/improperly torqued receiver extension nut; wrong extractor spring assembly; unstaked carrier key; out of spec gas tube receiver end; no feedramps or Dremeled in feedramps; commercial chamber instead of NATO chamber; overbored or eccentrically bored bolt carriers; improperly mounted FSB; use of old stock standard FSB instead of F dimensioned and marked one; wrong front sight post height; low grade small parts (QC fail from compliant manufacturers) and commercial receiver extension instead of Mil-spec. There are surely more things than this, but this is what you see over and over.

 

[Wayne Dobbs]

When you have said sub-par gun, with a Gas key that needs staking, do you replace screws? Where do you obtain these screws? Is there an approved list?

I'd recommend that you buy a Colt or BCM carrier key and screws for this situation. Colt parts are available from Brownell's and Midway, while BCM's are available from them. Make sure you do the proper prep before you install. Degrease the bottom surface of the carrier key and the top of the bolt carrier where the key mounts. Apply a small bead of Permatex (or similar liquid gasket product) around the gas inlet hole on top of the carrier. Set the key on the carrier, start the screws and torque them to a setting of 50-58 inch-pounds and then stake the screws (recommend a MOACKS).