Upgrading BCG in AR Platform?

If I upgrade to a nicer BCG, do I need to look into a new buffer tube as well.


What is wrong with the BCG you have now?

No, it’s not necessary. Unless there is a great design change or weight from original. If lighter or heavier could be compensated with an adjustable gas block or buffer spring.


The upper receiver parts need to be run wet. Take the bolt out of the carrier and apply a generous amount of CLP. Do the same for the inside and outside of the bolt carrier and the inside of the upper receiver. Also, apply CLP on the body of the charging handle and a drop on the latch pivot points. Last step is the put a small amount of gun grease (Tetra) on the locking lugs. Be careful not to get any (too much) CLP on the firing pin or in the firing pin channel and chamber.


It appears that you are looking to do some upgrades to your rifle. Again, in my opinion, the best money spent is upgrading to a good trigger. Geissele Is the best. Be warned though, you will be spoiled once you get one, and then want to upgrade your trigger in everything.

As far as the bcg, a lightweight unit will give you an improvement you can feel, but you need to use it in conjunction with an adjustable gas block so you can dial back the gas.

I’ll give you $50 for your old one if you upgrade.


What are the complete specs (best you know) of your rifle currently?

What do you intend to use this rifle for?


I am doing some minor upgrades to my M&P sport 2 but I’m not planning on upgrading anything that plays a part in the actual firing of the rifle as of right now. My M&P sport 2 may not be the highest quality rifle, but it is currently very reliable and I don’t really want to interfere with that.

I have a side project with a palmetto lower and upper I plan to do some experimenting with.

That way I have my dependable rifle and the then I have my “fun” rifle that could turn out being just as reliable.


What is you goal? Home defense, target shooting, defending the southern border?

Don’t get me wrong, there is nothing wrong with spending money and time on a hobby.

For this build it’s a hobby.

Down the road I’d like to put something together that is reliable but also operates smoother than my M&P. It doesn’t bother me, but pulling the charging handle on an M&P is not super smooth. It works and is reliable, but I know it could operate smoother.

What’s nice too is let’s say I decide to purchase a nice BCG and I put it in my palmetto. If, down the road, aero precision has a good deal on an upper, I can put the nice BCG in that upper and go from there.

I like to discuss and ask questions on here, but I often don’t just run and go buy everything right away. What will probably happen is instead of spending more money on my AR I’ll be posting about a new handgun I shouldn’t have bought :stuck_out_tongue_closed_eyes:.

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RE: Smoother operation, how many rounds have you fired through it?

Just my opinion, but if you are talking about getting nice stuff and upgrading down the road, I’d set your sights higher than S&W/PSA/Aero for that. You have the time, after all.

The funny thing with BCG’s whether $50 versions or $250 Nickle Boron Unobtanioum is that they either work or they don’t.

Is there any wear on the BCG itself? Something that would indicate binding in the upper?
Any wear on the bolt itself to indicate the same as above?
Wear on your charging handle is NOT indicative of a poor BCG it just means you pull the handle sideways.

You can improve the bolt function of the BCG by polishing the “run way” where the cross pin rides back and forth to lock and unlock the bolt and that generally fixes a multitude of sins.

If there is a particular “wear spot” on your bolt then close inspection of both the bolt and the BCG are in order to figure out which is the culprit.

I don’t baby my sticks but there is one thing I am fanatical about and that is the cleanliness of my bolt and BCG and comes from the realization and study that AR’s sh!t where they eat. If you use grease on the bolt make sure it is HIGH TEMP and not axle grease or something. The gas from the gas port/block/tube/key way fires straight down on the bolt inside the BCG. It’s hot and dirty in there.

A note on Key Ways: MAKE SURE THEY ARE STAKED AND STAKED CORRECTLY. If you ever have to take one off throw it and the screws away and get new then stake them. Loc-Tite is also required. If they get loose you will destroy your gas tube if you are lucky, upper if your not and it can get worse from there.

If you have to buy a BCG get one assembled with a bolt in the same coating. Nitride, Nickle Boron, Phosphate, Stainless what ever but get them the same. Dissimilar metals and or dissimilar coatings is one less thing you need to be worrying about.




Like many firearms, they will generally run reliably either dry or dirty, but not both. Lube well.


No you don’t need to, and why are you “upgrading” your BCG anyway?

I was thinking about this topic too but from the standpoint of buying a backup BCG in case something breaks. Is it worth it or should I just buy individual pieces like firing pin, retaining pin, extractor, etc.?

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IMO if you only have the one rifle, it’s a very good idea to, at MINIMUM, have a spare bolt rebuild kit basically. Firing pin with retaining pin, cam pin, extractor/springs/oring, but for me, if I only had the one AR, I’d want a complete spare BCG. If funds are limited, split the difference on the bolt, carriers with properly staked keys are much less likely to ever have a problem than the high stress bolt/lugs.

I have multiple AR’s and still have a complete, proven (465 rounds fired through it) BCG all oiled up in a drawer.

Other good spare parts to have IMO are basically a new Lower Parts Kit (LKP) minus the grip and FCG (fire control group) though I would include trigger and hammer springs in that.

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Makes sense. How do you store it? Put some oil on it, throw it in a Ziploc or something?

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That is what I do. Heavier plastic zip bags I have an assortment from from various parts orders, I coat with oil and put them in…some I put back in the packaging they came in which is invariably a plastic bag or plastic clamshell thing.

BTW: This is another thing that made me veto FrogLube. I had some of it on parts for storage and it turned into a gummed up ridiculous mess after awhile.


So there’s no difference in performance or operation at all?

I’ll look into what Craig mentioned about polishing. I figured the nicer BCGs, would have less friction. My BCG is totally functional and fine, but it is rough material. I figured a smooth bcg might lead to some benefits in the operation of the rifle.


Not a fan of nickel boron BCG’s anyway

Although Wilson Combat makes good stuff.