All purpose "Help me build my AR" thread.

[Jeriah]

http://www.calguns.net/calgunforum/show ... p?t=226178

This thread suggests I am GTG with either standard or H. Any reason I shouldn't try my standard before spending another $22 on a heavier buffer? Like, will it blow up my face? Also, I'm using mostly shit (Wolf, Herter's) ammo, which is probably underloaded. Is this a factor one way or another?

[TheLastOne]

my standard spikes was insufficient with wolf with my bcm upper at milcopp. i ordered an h as soon as i got back. It was short stroking or something: failures to extract/dbl feeds o plenty.

[williaty]

http://www.calguns.net/calgunforum/showthread.php?t=226178

This thread suggests I am GTG with either standard or H. Any reason I shouldn't try my standard before spending another $22 on a heavier buffer? Like, will it blow up my face? Also, I'm using mostly shit (Wolf, Herter's) ammo, which is probably underloaded. Is this a factor one way or another?

Again, if the gas system is properly designed and manufactured, the standard CAR buffer is the "correct" buffer. The heavier buffers are for when the system is "overgassed", meaning that there's a higher than expected gas pressure and volume blown back into the action. This can be due to anything from Bushmaster making the gas ports too large in order to get them to cycle dirty with weak cheapassed ammo to a necessary compromise to get extreme SBRs to work to the result of gas port erosion. Weaker ammo in 223 will likely require a lighter buffer to cycle while mil-spec ammo in 556 may be tolerant of a heavy buffer. BCM says CAR or H, IIRC. The gun will run safely with either. My methodology for picking a buffer has been to function test the gun for the first time on a CAR, then increase buffer weight until the action stops locking open on an empty mag on the rage under ideal conditions. Then lighten up one buffer weight to ensure reliable function in the real world.

[Jeriah]

my standard spikes was insufficient with wolf with my bcm upper at milcopp. i ordered an h as soon as i got back

OK. I guess what's getting me is, there's all these variables, and I don't understand how they interact. It's $22 now for something I might not need, vs. $22 + shipping later if I find out I do need it. Not the end of the world either way, but the range trip to find out is a bit of a bitch as well, living in Chicago as I do, so I'd rather not waste the money if I don't need it, but I'd rather not find out later if I do.

My Bushmaster so far has a Carbine buffer, carbine length gas system, and a semi-auto BCG. It eats Wolf fine. Haven't fed it much hotter shit but seems to be fine.

The upper I am ordering has a mid-length gas system, and an auto BCG. Common Internet wisdom seems to be that a middy is fine with a carbine buffer, and it's carbines that need H buffers, BUT that the auto BCG changes things somehow. That's the part I don't understand.

Again, if the gas system is properly designed and manufactured, the standard CAR buffer is the "correct" buffer. The heavier buffers are for when the system is "overgassed", meaning that there's a higher than expected gas pressure and volume blown back into the action. This can be due to anything from Bushmaster making the gas ports too large in order to get them to cycle dirty with weak cheapassed ammo to a necessary compromise to get extreme SBRs to work to the result of gas port erosion. Weaker ammo in 223 will likely require a lighter buffer to cycle while mil-spec ammo in 556 may be tolerant of a heavy buffer. BCM says CAR or H, IIRC. The gun will run safely with either. My methodology for picking a buffer has been to function test the gun for the first time on a CAR, then increase buffer weight until the action stops locking open on an empty mag on the rage under ideal conditions. Then lighten up one buffer weight to ensure
reliable function in the real world.

OK, that's starting to make sense. I think I'm going to leave the H buffer off my order, and if the action seems to slam too hard (moving too fast) and/or I'm getting failures to feed or something, I will immediately order an H buffer. (I will bring my old upper to the range as a spare, of course, so I'm not out a day of shooting when I find this out.)

[TheLastOne]

Yeah I didn't really pay any attention to my buffer until this class. I run a carbine length, bcm upper, bcg, barrel, spikes complete lower. Never had any trouble with Privi 193, Lake city, or other Federal. This was my first wolf experience. Wasn't a huge deal at class, I just got better at clearing dbl feeds and everyone got a laugh

I plan on shooting more wolf, so I'm switching buffers. Next time I get to do srs wolf business, I'll pop in a report if it functions better/worse.

[Jeriah]

Oh man...I think I'm about to pull the trigger on a $1,200 purchase...yeesh, I'm scared. Do I pay it on my debit card, thus not putting anything on the credit card? Or do I put it on the credit card just in case...in either way, there is supposedly a $2K plus check sitting for me in the gallery...oh god, Mommy I'm scared...

[williaty]

The upper I am ordering has a mid-length gas system, and an auto BCG. Common Internet wisdom seems to be that a middy is fine with a carbine buffer, and it's carbines that need H buffers, BUT that the auto BCG changes things somehow. That's the part I don't understand.

The internet either doesn't understand things or what they understand is based off using cheap parts that aren't in spec. Either is very, very likely. A 14.5" barrel with carbine gas, properly executed, should cycle optimally with a CAR buffer. A 16" barrel with midlength gas, properly executed, should cycle optimally with a CAR buffer. In fact, I do believe a 20" barrel with rifle gas but a carbine buffer tube and spring should also cycle optimally on a CAR buffer. The reason for this is that the carbine, midlength, and rifle gas systems are all designed to dump the same amount of energy into the BCG when matched to the design barrel length. Note that the time domain of the energy dump is different, but the total energy transfer is supposed to be the same. The buffer in combination with the spring is designed to soak up a specific amount of energy over the length of the tube and then use that stored energy to return the gun to battery. The design basis has the spring bringing the buffer to 0 velocity just slightly past the end of the receiver tube. In other words, the system is designed to thump the buffer into the end of the tube a little bit to ensure that, on a light cartridge, it actually makes it all the way to the end of the tube.

This breaks down when you get the gas system out of spec. For instance, if you take a midlength gassed barrel and cut it down a bit, things get wacky (shorter barrel in front of gas port reduces energy transfer to BCG). If you put a suppressor on the gun, things get wacky (suppressor forces more gas back through the gas system, dumping extra energy into the BCG). If you make the gas port too large, things get wacky (large port=more gas=more energy). When things get wacky, we have to take remedial steps to make the gun run properly again. If there's too little energy going to the BCG, the spring+buffer will arrest the rearwards motion of the BCG before the BCG has traveled enough to extract the spent casing and allow the new cartridge to rise out of the mag, or it may have insufficient return energy to push the new cartridge fully into the chamber and lock into battery. The general advice in this case is "don't shoot shit ammo" but really, you should be trying to figure out why there's either not enough energy or too much friction. If the gun has the other problem, too much energy, the action can cycle so quickly a whole host of problems can go wrong. However, we have a set of "band aids" in the form of heavier weight buffers readily available. The heavier buffers require more energy to get them moving at a given speed. This slows down the action, giving more time for each step of the cycle to happen, making those steps more likely to complete successfully. There's some big potential reliability gains to be made from slowing the system down, especially in terms of extraction, since longer time before unlocking means more heat transfer out of the case.

So, you need a light enough buffer to cycle the action the full distance but a heavy enough buffer to allow time for things to happen.

OK, that's starting to make sense. I think I'm going to leave the H buffer off my order, and if the action seems to slam too hard (moving too fast) and/or I'm getting failures to feed or something, I will immediately order an H buffer. (I will bring my old upper to the range as a spare, of course, so I'm not out a day of shooting when I find this out.)

Since you already have a CAR, I'd buy the H. Your new rifle will probably cycle just fine on an H so long as you don't use 40gr ammo loaded with powder made from the bones of the oppressed underclass. If, by chance, it doesn't, pop the CAR from your existing rifle into your new one, have fun with your range day, and then order a CAR when you get home.

[Jeriah]

So, an H is better if it works at all, because it makes shit run slower, and you want shit to run as slow as possible, as long as it does go all the way?

And a CAR might work but might cycle too fast, in which case I might get failures to feed or something?

I think I'm going to buy everything but NOT the H buffer, because a.) the CAR buffer works with my current upper and I'd like to be able to go back and forth between uppers if need be, and b.) if it'll run with the CAR I'd rather not have a spare buffer in the parts box. And if it doesn't run with the CAR, well, I'll eat the eight bucks shipping if I have to order the H later.

Thanks so much for the really good explanation, though. I think I get it now.

I just need another glass of wine to work up the courage to place the order.

[Jeriah]

Oh fuck. I did it. I'm giddy. I think I'm about to pee myself.

Someone once said, "Fuck you, Zombie Squad. If it wasn't for you, I'd own my own house by now." It's so goddamned true.

[shiddymunkie]

shelter is overrated

[TheLastOne]

Plus, you'll likely get a hat to keep the rain off!

Congrats on the buy, give us a picture when it shows up (and it will ship tomorrow, those fuckers at BCM are really good about getting stuff out).

[Jeriah]

Plus, you'll likely get a hat to keep the rain off!

Congrats on the buy, give us a picture when it shows up (and it will ship tomorrow, those fuckers at BCM are really good about getting stuff out).

They sent me a thing saying it should arrive Tuesday. I have to teach...oh no, wait, I don't! But I may chain Steph to the radiator anyway, just because it's hot. I mean, sexy. They're not on this time of year.

Photos for sure. We have a range date in a couple weeks.

[Vicarious_Lee]

So, an H is better if it works at all, because it makes shit run slower, and you want shit to run as slow as possible, as long as it does go all the way?

And a CAR might work but might cycle too fast, in which case I might get failures to feed or something?

As I understand it, this is exactly the case. Dave and others have said that you want as much mass as will reliably cycle your ammo. Slow and smooth. Less chance of banging your BCG and "bolt bounce". I have a DD middy with DD BCG and H-buffer. It will cycle everything (Hornady, Tracers, M855, Wolf Military Classic, etc.) EXCEPT some cheap-shit Tula that won't even cycle in my overgassed Sig 556 on the low setting. So, to me that means that I've got it slowed down just right, because it'll eat Wolf 55gr all day, but won't cycle the bottom of the barrel shit.

You should get a DD rear sight. It's cheaper, Dave runs one, and it's so light that it actually subtracts weight from your gun.

About optics: I think the Aimpoint Micro has several distinct advantages over the EOTechs, and by "several" I mean "two".

1. It, in a DD mount, is less than half the weight of even the lightest EOTechs.

2. If you have a Sig 556 like I do, it's slim enough that you can work the charging handle easier (and it's light, because the Sig 556 is heavy, sort of).

Otherwise, yeah EOTech all up in my bunghole! I'm a fanboi.


Hey, so "Build my AR" thread, I've got a problem. I've built an AR. It's amazing. It's run MilCopp just fine. It's beautiful, fast, and handy from 0-300 meters. It's everything I want and probably nothing I'll ever need.

So now what do I do?

[TheLastOne]

Start selling your glocks and buying Sigs.

Then start looking over the fence at all your internet neighbors who run AK's and wonder what that is about. Then start thinking AK's are pretty tits after all.

Right here you should probably just leave your wife, so when she takes half your stuff, it won't be after you have way more guns to divy up.

Then you're going to need at least 2 AK's.

By then you'll figure you need a $7000 safe to hold all that shit. Then you realize how much safe room you have, and you may as well get some more guns to fit in there.

Hey, what's an ACOG? Oh, only $1300 (unless you buy off Kutter right NOW). Wow, those acogs sure are shiny.

Damn, I should get a can for all of my guns too. And, hell, while I'm filling out paperwork, why not work on a few sbrs? Shit, better do at least two AR sbrs and at least one AK sbr.

Fuck, there's an election soon, better get some more ammo too; prices are going up.

Damn, those BCM and HSP shirts sure are sexy, better grab a few.

Oh crap, BCM has bcg's in stock, better get a couple for those 'maybe' builds I'm planning on. Oh fuck, all these carbines and I don't have a DMR??

Yeah, that should keep you busy for a few months

[Regular Guy]

^^^

Apart from the carbine VLee, if you can, suppression devices. Benefits are amazing.

[jeepinbandtrider]

So, an H is better if it works at all, because it makes shit run slower, and you want shit to run as slow as possible, as long as it does go all the way?

And a CAR might work but might cycle too fast, in which case I might get failures to feed or something?

As I understand it, this is exactly the case. Dave and others have said that you want as much mass as will reliably cycle your ammo. Slow and smooth. Less chance of banging your BCG and "bolt bounce". I have a DD middy with DD BCG and H-buffer. It will cycle everything (Hornady, Tracers, M855, Wolf Military Classic, etc.) EXCEPT some cheap-shit Tula that won't even cycle in my overgassed Sig 556 on the low setting. So, to me that means that I've got it slowed down just right, because it'll eat Wolf 55gr all day, but won't cycle the bottom of the barrel shit.

You should get a DD rear sight. It's cheaper, Dave runs one, and it's so light that it actually subtracts weight from your gun.

About optics: I think the Aimpoint Micro has several distinct advantages over the EOTechs, and by "several" I mean "two".

1. It, in a DD mount, is less than half the weight of even the lightest EOTechs.

2. If you have a Sig 556 like I do, it's slim enough that you can work the charging handle easier (and it's light, because the Sig 556 is heavy, sort of).

Otherwise, yeah EOTech all up in my bunghole! I'm a fanboi.


Hey, so "Build my AR" thread, I've got a problem. I've built an AR. It's amazing. It's run MilCopp just fine. It's beautiful, fast, and handy from 0-300 meters. It's everything I want and probably nothing I'll ever need.

So now what do I do?

Build another one. I'm buying a stripped lower on the first to build a pistol then have an A4 clone planned after that.


Sent from my iPhone

[0122358]

After reading all that tenchno mumbo jumbo about H-buffers, im just going to try an extractor upgrade and better magazines on my olympic arms in order to shoot
Wolf. If im still having problems, then ill come up with some more stuff i need from BCM and throw the H-Buffer in there as well

[Regular Guy]

Start selling your glocks and buying Sigs.

BLASPHEMY!

[majorhavoc]

PSA has their MOE LPK on sale for $49.95 through tomorrow, ships free.

http://palmettostatearmory.com/index.php/ar-15-05/lower-parts/parts-kits/palmetto-state-armory-gen-2-moe-lpk.html

It's their classic kit with a MOE grip substituting for the regular A2 grip, otherwise nothing special.

Good price for a low cost build. FWIW, I've been very happy with mine.

FYI: PSA has been very slow to ship orders lately. Once the items get out of house, it comes very quickly, but my last order for an instock item was in "processing" status for a full week before it left the warehouse. YMMV

[Rev]

Start selling your glocks and buying Sigs.

BLASPHEMY!

I sold a Sig and bought a Glock. Am I doing it wrong?

[Jeriah]

Hey, speaking of MOE pistol grips...

So since I got the MOE handguard in FDE on my new upper, I'm wondering if I ought to get matching a matching FDE pistol grip and buttstock on my lower, so it's all matchy-matchy. I've been using a standard A2 grip and an ACE M4 stock (2005 vintage), both in black. They work fine. I have giant monster hands and could easily handle a larger grip; the stock is fine but I'd like something in FDE so it matches and also so it doesn't get so hot in the sun.

I was about to ask some shit about buffer tube diameters and stuff, but fuck it, I'm just going to paint the old one with Kylon ultra-flat and see how it works out.

Might do the same with the pistol grip, but...does the MOE grip offer any real advantage? I can imagine it being more comfortable but I'm used to the A2, I always run it with gloves. Is this a case of "if it ain't broke, don't fix it," or more a case of "Dude, once you try MOE, you'll never go back"?

[TheLastOne]

Hey, speaking of MOE pistol grips...

So since I got the MOE handguard in FDE on my new upper, I'm wondering if I ought to get matching a matching FDE pistol grip and buttstock on my lower, so it's all matchy-matchy. I've been using a standard A2 grip and an ACE M4 stock (2005 vintage), both in black. They work fine. I have giant monster hands and could easily handle a larger grip; the stock is fine but I'd like something in FDE so it matches and also so it doesn't get so hot in the sun.

I was about to ask some shit about buffer tube diameters and stuff, but fuck it, I'm just going to paint the old one with Kylon ultra-flat and see how it works out.

Might do the same with the pistol grip, but...does the MOE grip offer any real advantage? I can imagine it being more comfortable but I'm used to the A2, I always run it with gloves. Is this a case of "if it ain't broke, don't fix it," or more a case of "Dude, once you try MOE, you'll never go back"?

I personally don't seem to notice a huge difference between grips My spikes lower came with an A2, I put on a MOE, and then got one of the new BCM grips when they came out to maintain my poser status. Honestly, they all work fine for me, ymmv. I have hands that fit medium mechanix gloves perfectly, though I prefer large for extra flexy room. Dunno if grip differences are more noticeable for larger hands. I grabs it, I shoots it, I smile.

Grips are pretty cheap, maybe try one out: should be easy to sell if it's not your cup of tea.

[TheLastOne]

Start selling your glocks and buying Sigs.

BLASPHEMY!

Ha, I snuck that one in for you

[jeepinbandtrider]

I wouldn't care about matching so much but the MOE components are good to go.