AR Buffer Question

[Okiegunner]

I have recently made my very first AR purchase. I bought a very base, mostly Mil-Spec AR platform. I am in the process of doing some parts upgrades (one reason I purchased a base rifle, was in order to add some personalized parts and not spend the whole bank)

My buffer question is...

If I add a BCM "auto" BCG, will I need to also get an H or H2 buffer? Will my standard M4 carbine type buffer be sufficient?

I do not know. This is my first AR purchase. As a project and hobby thing. I will eventually purchase a LMT or BCM (blem) lower and do a complete build. It will involve learning some new things for myself, but thats OK. At my age it is good to keep the mind sharp!!

The rifle I now have should be a good way to familarize myself for a future build.

I used to field strip these things 40+ years ago in the service, but that is as far as it ever went. A future build should be a "fun" project.

Thanks much for the feedback

 

[HOOfan_1]

The Auto BCG is heavier than a semi-auto BCG which adds additional inertia, so upgrading the buffer is not necessary if your current set up works ok.

 

[WinThePennant]

What length is your rifle? It sounds like it might be a carbine.

For middies, I go with an H Buffer. For carbines, I go with an H2.

I run with full-auto BCGs.

 

[Okiegunner]

Thanks guys...I am learning here.

The rifle is a M4 type, 16 inch barell.

 

[HOOfan_1]

Thanks guys...I am learning here.

The rifle is a M4 type, 16 inch barell.

M4 profile barrels have a shorter carbine gas system. You will see a narrow place in the barrel, about 1.5" long about 4 inches from the muzzle. That is the cutout for mounting an M203 grenade launcher.

The shorter the gas system, the more time the gas has to act on the gas key before the bullet exits the barrel and depressurizes the system. Military M4s have 14.5" barrels, for us civilians to use those, we would either have to register it as a short barrel rifle and pay the tax stamp, or have a 1.5" or longer flash hider/compensator permanently welded to the barrel.

Many people advocate that a 16" barrel needs the longer mid-length gas system. Or you can just add the heavier buffer.

I have a 16" carbine gas system with a full auto carrier and an H buffer, and I have no problems with it. Someone who likes to pop off rounds in quick succession may find the muzzle climb excessive though.

 

[madcratebuilder]

The FA carrier is 11 grams heavier than the SA carrier, or about .7oz. Here are the buffer weights.

Carbine 3.0 oz
H buffer 3.8 oz
H2 buffer 4.6 oz
H3 buffer 5.6 oz

16" carbine gas I would start with a FA carrier and a H buffer or a SA carrier and a H2 buffer. Either setup well have basically the same reciprocating weight.

 

[gotigers]

No, reason to change anything unless it isn't cycling properly.

I use full auto carriers with H2 or Spikes ST-2 buffers in all new .223/5.56 rifles. The ST-2 is my favorite.

 

[Infidel4life11]

I run heavy buffers on everything. I have a ST-T2 in my mid 16" CMMG, Car 16" RRA and Car 16" M&P Sport. You don't need it but it mos def helps out.

 

[Okiegunner]

All right...Thanks guys...

Learning here, OK?

Let me see if I have this right. I currently have a M4 "type" 16 inch carbine. It came stock with the SA BCG and carbine buffer. I am upgrading (got email shipping verification today) to a heavier Bravo Company "auto" BCG.

If I understand the comments correctly, while not nescessarily needing the H2, I should replace the buffer standard carbine buffer with the H.

Is this correct? This is all new to my expertise, but I am learning.

(on a side note...and a lot of you would have told me to just spend the $$ and buy the completed more expensive rifle initially. However, I wanted to "kind of" build the rifle. Gives an old man a little hobby. There are several guys I work with that own an AR of some sort. I may have a chance to pick up a LMT fully complete lower for around $250.00)

Anyway, Best and thanks for the help...

 

[Quentin]

You have not told us for certain whether you have an "M4" with carbine length gas or midlength gas. Carbine length handguards are about 7" long and midlength about 9". As has been said before this does matter. I have three midlengths with FA BCGs and H-buffers which should be a good choice for most middys but it depends on the rifle and what ammo you'll use.

Anyway, for now I'd just use the standard buffer you have and see how it functions. We can give suggestions but really it comes down to what works best in your rifle.

As I said in your other post it might be best to leave the DTI stock and start collecting top grade parts to do a new build on the LMT lower. The BCM BCG is a great start.

BTW, I'm an old guy too. (64)

 

[Kurt_D]

All right...Thanks guys...

Learning here, OK?

Let me see if I have this right. I currently have a M4 "type" 16 inch carbine. It came stock with the SA BCG and carbine buffer. I am upgrading (got email shipping verification today) to a heavier Bravo Company "auto" BCG.

If I understand the comments correctly, while not nescessarily needing the H2, I should replace the buffer standard carbine buffer with the H.

Is this correct? This is all new to my expertise, but I am learning.

(on a side note...and a lot of you would have told me to just spend the $$ and buy the completed more expensive rifle initially. However, I wanted to "kind of" build the rifle. Gives an old man a little hobby. There are several guys I work with that own an AR of some sort. I may have a chance to pick up a LMT fully complete lower for around $250.00)

Anyway, Best and thanks for the help...

STOP, just STOP don't waste another dime. Shoot the stupid thing and see if there's issues FIRST. Heck, what band is it? It may already have an MPI tested bolt (doesn't really do anything) and M4 extractor spring or O-ring.

Going from a semi cut carrier to a FA was a complete WASTE of money, period. I don't care what lenght gas system there is NOT enough weight gain to amount to jack. The BCM bolt may have their upgraded extractor spring which would be cool if the rifle actually had extraction issues; even then there's a .50 o-ring to solve that.

A H buffer does slow down the cyclic rate but it may not be needed. Yes, you can over buffer the gun and cause short strokes, especially on under powered .223 ammo. I have H buffers in my 14.5 Bushy and 16" Colts. Colts are OEM, I upgraded the Bushy to smooth out the recoil pulse and they all feel about the same now. I guess what I'm trying to say is try the stock set up first.

Going to a LMT or BCM lower is another waste of money unless your new rifle is somehow damaged, then that's what warranty is for. A forged lower is a lower is a lower; no sense is changing unless you want a different picture on the side. The receiver extention might be the only difference (again don't know what brand the current rifle is) and that's mil spec dia vs commerical; and they make stocks to fit both or the tubes are easily changed.

Something else - a lot of the parts, especially small parts, are from the same sub-contractors. That's right Colt, DPMS, Bushy, LMT, BCM, and everyone else most probably get their fire control parts, springs, etc from the same 1 or 2 sources.

Don't get me wrong, it's OK to order up on spares but don't just start replacing parts because someone, somewhere said this was better than that. You'll figure out fast if you read ar15.com's forums there is ALWAYS a flavor of the month that EVERYBODY and their momma recommends and you must have... only later to find out it ain't all that or what worked before still does or now everyone hates said vendor. If there's an issue then fix/upgrade it. Otherwise save the money toward ammo, mags and other accessories you might want; like mounts, rails, grips and/or optics.

 

[Kurt_D]

One last thing - as a "hobby", more of an addiction, use you current AR and see how everything works. Then you can build another one from the ground up: figure out what you want: SBR, retro, A2, A4, long range, etc; start with a stripped lower and upper and put it all together. And then build another, and another...

 

[WinThePennant]

Personally, I don't think going to a BCM full auto BCG is a waste of money. Those are some great BCGs!

Buying a whole new lower is probably a waste, but upgrading parts are not. Consider putting some KNS anti-rotation pins in there. Those things are great, and they will smooth out a mil-spec trigger.

 

[sansone]

ejection of spent casings should fly between 3:00-4:30 clock position if correct gassing occurs.
Forward of 3:00 position = overgassed (needs heavier buffer)
Aft of 4:30 clock position = undergassed

 

[Jeremy2171]

I'm with Kurt on this one...

 

[Fishbed77]

I'm with Kurt on this one...

Same here. My AR-15s happened to come with FA bolt carriers, but if they didn't, I certainly wouldn't waste the money to buy one.

 

[sansone]

hello Okie,
shoot it while standing with a clear path to your right, take notice of where the spent cases land in relation to the rifle.

The muzzle points towards 12:00 horizontally, so 3:00 would be directly to the right of rifle. Slightly rearward of straight out sideways would be 4:30 (directly behind = 6:00)

forward case ejection, 1:00-2:30 / would require a heavier buffer or stronger buffer spring..
rearward ejection, (5:00-5:30) would require lighter buffer / 3:00-4:30=good

 

[Okiegunner]

OK, I think I got it.

The "M4" I have is pretty much a base mostly "mil-spec" rifle. The only things I am replacing are the CH and the BCG. Probably don't need to, but I figure the BCM "Gunfighter" CH and the BCM FA BCG are some quality parts (and...to be honest...they look kinda cool too).

I will see how the rifle cycles first, and if need be, then I will look at replacing the buffer.

I have not bought another lower. The LMT would be for a future build, that is, once I have familarized myself enough with this rifle. $250.00 for a like new complete LMT lower seemed like a really good buy.

Thanks all for your feedback

I do listen and pay attention

 

[Tirod]

Cool is your choice, but I avoided all the HSLD gunfighter parts on my build.

The operation of the AR15 means you charge it once, "in the wire," and from then on, the bolt hold back does the work for you everytime you empty the magazine.

If there is a problem with constantly charging a gun that can't chamber a round, it needs to be fixed - not bandaided. It's the competitive shooters that use those charging handles because the course of fire forces it, and they are on the timer down to the split second.

Everyday use, even combat, nobody has yet showed it was necessary. It's NOT a part the military has bothered to pick up and issue.

Auto bolt carrier is just an option. They don't wear out, most sell because of looks and an intellectual want to, not functional reliability. As said, if that's what you want - get it on the first gun. Otherwise, you sink more $$ into something, and pretty soon, you have a $2000 gun and $200 in used parts. I'm cheap, I built mine from scratch to avoid that.

The key to remember with all the cool parts is that companies make things because they can sell them - not because they are better. And most of the buyers who post up about how great they are need to justify their money being spent. It's about 90% of the recommendations - they don't give you a factor on how it improved the mean rate of failure between rounds, or a minute of angle reduction. It's just cool.

Take most of the advice on open forums with a deer block sized grain of salt - these kids aren't experts by any means, they just have credit cards. And they like using them, after all, spending money on stuff with diminishing returns isn't something they broke themselves of yet.

BTW, I built a fixed A1 stock, A4 flattop, A2 rifle handguard with 16" barrel in 6.8, fixed front sight. A bit different, but each part has a distinct purpose to the overall intent, cold weather shooting in the woods for a live target. Not one part is GI, but many are better quality. Don't get caught up in the trap that milspec is somehow the best, it's just a production standard the military imposes. They know what they need to get their 2MOA performance at the lowest contract bid price. It's really not hard to do that. Considering it's 100% Made in America and the price is right.

If they imported these things, we'd buy AR15's for $350 - consider who's behind some of the BATF restrictions before we blame them.

 

[WinThePennant]

What people are saying is true - You don't need a super cool AR with super expensive parts.

But - That isn't the point.

I have plenty of 'expensive' parts on my AR. Some for functionality, some for fun, and some for peace of mind.

Why do I overpay for quality parts? Well, I do so for a lot of reasons (not just with ARs, but with every thing). Mostly, because I know it will work to perfection. I'm old enough to know that there are areas of my life that I want to work to perfection, and I'm not going to take a chance. I'll buy a cheap garden hose. I'll buy a cheap broom. I won't buy cheap gun cases I use to transport pistols on airplane flights. See my point?

Do I buy expensive parts for the whole gun? Certainly not. For example, I run Magpul MOE handguards on my ARs. They are perfectly reliable, look great, and cost almost nothing. All I do is hang a light and a sling on my handguard. I don't waste my money on vertical or angled grips.

Frankly, I'm a little surprised that people suggest that you scrimp on a BCG. That's an area that I'll NEVER scrimp on when it comes to ARs. Well, that and mags. I only run on PMAGS.

If you are looking for a real 'technical' reason as to why a full auto is better than a semi, then you can always say that you want the softer recoil a full auto offers that will lend itself to longer parts life of the gun.

Now, if you were talking about hanging a $300 SureFire light on a $300 Daniel Defense Lite Rail, well, then I'd suggest different options that have a better cost/value ratio.

 

[SilentScream]

I would have to concur with most of the advice given already, shoot it stock (you most likely won't have any issues) then if you want to customize/accessorize go for it. Notice i didn't say upgrade, mostly because 90% of what is labeled as "upgraded" isn't. Just some new gadget, gizmo, or toy to hang on your rifle. Just to give you an idea of where I'm coming from, I've been shooting the same A2 since 2002.

 

[Jeremy2171]

ejection of spent casings should fly between 3:00-4:30 clock position if correct gassing occurs.
Forward of 3:00 position = overgassed (needs heavier buffer)
Aft of 4:30 clock position = undergassed

This is only true if your upper has a Brunson Bump ie "case deflector".


My slickside uppers all put the brass around 4-5:00.

 

[Kurt_D]

OK, I think I got it.

The "M4" I have is pretty much a base mostly "mil-spec" rifle. The only things I am replacing are the CH and the BCG. Probably don't need to, but I figure the BCM "Gunfighter" CH and the BCM FA BCG are some quality parts (and...to be honest...they look kinda cool too).

I will see how the rifle cycles first, and if need be, then I will look at replacing the buffer.

I have not bought another lower. The LMT would be for a future build, that is, once I have familarized myself enough with this rifle. $250.00 for a like new complete LMT lower seemed like a really good buy.

Thanks all for your feedback

I do listen and pay attention

If the LMT is set up the way you want it already then yeah, otherwise buy a stripped lower and build it up your self.

On ejection, the path isn't as cut and dry as some would have you beleive. Switching from something like UMC or Federal .223 to mil spec xm193 or xm855 will change the path due to higher pressures. Also an o-ring or enhanced extractor spring will change the path as well. General rule is 3-4 is ideal but as long as it's reliable and locks back on the last round it's GTG.

ETA: not saying the BCM stuff isn't quality, it's just you won't see a difference between it and stock performance wise (BCG). Not like, say, a trigger change in which you will feel the difference instantly. Or a new stock were, again, you feel the difference instantly.