View Full Version : BCM PISTOL BUILD WITH THE NEW SBA3 BRACE!
bcmgunfighterohio
04-25-18, 08:39
My first build/semi-build. I assembled the lower and bought the upper assembled. Next build I will assemble the upper too. Which is actually gonna be my dads rifle.
Hes waiting on the kit in the mail.
Heres the breakdown:
11.5 inch bcm bfh upper with keymod alpha rail
anderson lower
bcm lpk
h2 carbine buffer
jp polished and center ground spring
sb tactical sba3 brace
bcmgunfighterohio
04-25-18, 08:43
Now, I do have a question about this gun. Please look at the attached picture. Does this look like the brass is hitting the deflector excessively hard? This is my first short barreled AR so im not sure if this is normal. All I know is that my 16 inch carbine AR does not leave brass on the deflector like this. This is after only 100 rounds or so.
How far and what direction is the brass going?
Try a heavier buffer?
bcmgunfighterohio
04-25-18, 10:08
How far and what direction is the brass going?
Try a heavier buffer?
Could not really measure distance due to lane size at the range. But they were exiting between 2 and 3 o'clock and hitting the screen between lanes. I was thinking about trying a differemt buffer, but im already using a h2 and it seems that bcm usually recommends a h buffer. But, I think i will go ahead and try a h3. There cheap enough and doesn't hurt to have different weights laying around anyhow!
bcmgunfighterohio
04-25-18, 10:10
Oh yea, I forgot to list the optic. Its a sig romeo 5 xdr. Havent decided on which buis I will put on it.
The H2 buffer is right. Next things to try are a Sprinco blue spring and an SLR adjustable gas block or the BRT Micro Port system. How does the recoil feel? Is it kinda sharp?
A BCM BFH upper on an Anderson lower? 0.o
A BCM BFH upper on an Anderson lower? 0.o
Yeah I noticed that too haha.
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bcmgunfighterohio
04-25-18, 17:41
A BCM BFH upper on an Anderson lower? 0.o
All the guts are bcm. Anderson lowers are available locally to me, and they make good lowers in my opinion. I would like to do a billet lower though.
One thing you will learn about AR owners and that is they are as gullible as fisherman buying into the latest best lures making them better fisherman . I have 5 AR lowers and 3 are Anderson 2 are "quality " brands and the only difference between them is Anderson don't charge for the name . I know it doesn't make sense but some times a heavy buffer can make it appear you are over gassed , something to do with the case not being swelled when removed from the chamber so try a lighter buffer and put layers of masking tape over deflector to check for strikes . Also cases can strike the deflector and bounce back to 3 o'clock and make it look like it's not over gassed when it is . WHAT AMMO should be the first question , try some known weak ammo and ck if it locks back on an empty mag .If it bothers you you might have to go adjustable block but it's not in itself a problem because that is why it's there and I would rather brass scuffing over short stroking .
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...a heavy buffer can make it appear you are over gassed...
Not if you know what to look for.
PS- An H2 buffer isn't a heavy buffer. The H2 is about right, if you're using a carbine RE.
Not if you know what to look for.
PS- An H2 buffer isn't a heavy buffer. The H2 is about right, if you're using a carbine RE.I aree it about right and I'm pretty sure he doesn't know what to look for or he would not have asked . There is not enough information to really advise him as he may not even have a problem but if it's marking with light loads he might .
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Ejection patterns and brass marks on the deflector are unreliable indicators of how an AR is gassed. The best way is a lock back check (to make sure the AR isn't short stroking) and how the recoil feels. If the buffer is bottoming out hard, the AR is over gassed and recoil will be sharper. That's assuming an H or H2 buffer is being used. Carbine buffers are just too light and recoil will often feel sharp even if the gas drive is correct.
bcmgunfighterohio
04-25-18, 18:48
One thing you will learn about AR owners and that is they are as gullible as fisherman buying into the latest best lures making them better fisherman . I have 5 AR lowers and 3 are Anderson 2 are "quality " brands and the only difference between them is Anderson don't charge for the name . I know it doesn't make sense but some times a heavy buffer can make it appear you are over gassed , something to do with the case not being swelled when removed from the chamber so try a lighter buffer and put layers of masking tape over deflector to check for strikes . Also cases can strike the deflector and bounce back to 3 o'clock and make it look like it's not over gassed when it is . WHAT AMMO should be the first question , try some known weak ammo and ck if it locks back on an empty mag .If it bothers you you might have to go adjustable block but it's not in itself a problem because that is why it's there and I would rather brass scuffing over short stroking .
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Yep, I have always been happy with anderson lowers. I have a lighter buffer in my m and p sport i can throw in it for experimenting. I like the tape idea. Thanks
bcmgunfighterohio
04-26-18, 05:45
I aree it about right and I'm pretty sure he doesn't know what to look for or he would not have asked . There is not enough information to really advise him as he may not even have a problem but if it's marking with light loads he might .
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Loads were with 55 grain bulk fmjbt seated to 2.25 inches. Im sure COL varies a bit due to the cheap bullets. 23.9-24.1 grains of h335 with br4 primers. Brass trimmed to 1.75.
bcmgunfighterohio
04-26-18, 05:52
Ejection patterns and brass marks on the deflector are unreliable indicators of how an AR is gassed. The best way is a lock back check (to make sure the AR isn't short stroking) and how the recoil feels. If the buffer is bottoming out hard, the AR is over gassed and recoil will be sharper. That's assuming an H or H2 buffer is being used. Carbine buffers are just too light and recoil will often feel sharp even if the gas drive is correct.
Forgive me for my ignorance. What is a lock back check? The bolt does lock back on empty mags.
Forgive me for my ignorance. What is a lock back check? The bolt does lock back on empty mags.Just what it implies , shoot with empty mag and it should lock back if it doesn't but locks back with the same empty mag when manually cycled it's under gassed - buffer too heavy - gas leak .with adjustable block you can use light buffer and adj block just enough to lock back on empty mag . Some people use light buffer for light and heavy for hot others use middle weight for everything and others use adj block to fine tune . If it's a just for fun gun it's ok to be just a hair more open than lock back but if your life might have to depend on your weapon not short stroking it's best to run open more or lighter buffer . That said I run standard carbine in my .556 carbine and H in my 12 1/2" 16"and 18" ARP 6.8S
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bcmgunfighterohio
04-26-18, 08:41
Just what it implies , shoot with empty mag and it should lock back if it doesn't but locks back with the same empty mag when manually cycled it's under gassed - buffer too heavy - gas leak .with adjustable block you can use light buffer and adj block just enough to lock back on empty mag . Some people use light buffer for light and heavy for hot others use middle weight for everything and others use adj block to fine tune . If it's a just for fun gun it's ok to be just a hair more open than lock back but if your life might have to depend on your weapon not short stroking it's best to run open more or lighter buffer . That said I run standard carbine in my .556 carbine and H in my 12 1/2" 16"and 18" ARP 6.8S
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Thanks ozark! The way you explained it makes a lot of sense. I guess I was paying too much attention to the brass strikes on the deflector and not thinking about the actual functionality of the gun. I know how the DI system works on an AR and I was not even applying it to my thought process. Thanks to everyone who gave input so far. Its all been helpful. Im new to the forum and I am glad I joined. Seems like a good batch of folks.
Thanks ozark! The way you explained it makes a lot of sense. I guess I was paying too much attention to the brass strikes on the deflector and not thinking about the actual functionality of the gun. I know how the DI system works on an AR and I was not even applying it to my thought process. Thanks to everyone who gave input so far. Its all been helpful. Im new to the forum and I am glad I joined. Seems like a good batch of folks.We don't always agree on everything and some of us get a little long on our explanations but everyone has been really helpful to me .
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Nice pistol. My question is how do you like the sba3? Mine still hasn't arrived and I'm anxious for some info on it. Do you like it? Is it solid? Does it lock up tight when adjusted? Your thoughts please.
A BCM BFH upper on an Anderson lower? 0.o
What's wrong with Anderson Lowers?
I've built plenty of Anderson and PSA lowers just fine with no issues. $50 stripped lowers are hard to beat.
BoltActionAssault
05-06-18, 21:43
What's wrong with Anderson Lowers?
I've built plenty of Anderson and PSA lowers just fine with no issues. $50 stripped lowers are hard to beat.
You can get an Aero Precision lower for around this price. Lots of solid in spec choices at this price point.
Nice little build. I also have an Anderson lower that I’m making a pistol. Waiting for the 10.5” aero upper to be delivered.
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Got my s a3 finally. I dig it! I think it's gonna make a great pistols. It's gonna be a on the cheap build. I think the most expensive part will be that brace. It will also be my very first AR pistol so I don't know if I will even like them (a pistol) so I'm not gonna sink much money into one, at first.
Yours looks like a quality build, BCM doesn't mess around. They're quality all the way. Let us know when you get the tune right and how she runs. Looks great. And, Anderson makes fine lowers. Some people, me included sometimes, feel better about themselves when their lower or whatever has a name on it, and there is nothing wrong with that either but if it doesn't have "that name" doesn't mean it's not completely fine.
Charlie Don't Surf
05-22-18, 08:10
I've assembled about 10 lowers. 2 LRB Arms, 1 BCM, 6 PSA and 1 Anderson. The Anderson was barely in spec, took some persuading to get it to mate with uppers. I worry about tolerance stacking with Anderson. It was the least quality of the lowers I've had in my hands. I'll pay the extra $10-20 and stay away from Anderson after that. Of course, its a sample size of 1.
I've assembled about 10 lowers. 2 LRB Arms, 1 BCM, 6 PSA and 1 Anderson. The Anderson was barely in spec, took some persuading to get it to mate with uppers. I worry about tolerance stacking with Anderson. It was the least quality of the lowers I've had in my hands. I'll pay the extra $10-20 and stay away from Anderson after that. Of course, its a sample size of 1.Need more information ,do you mean pins don't line up or tight fit between upper and lower ? What was out of specs ?
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Charlie Don't Surf
05-22-18, 11:42
Need more information ,do you mean pins don't line up or tight fit between upper and lower ? What was out of specs ?
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Trigger group pins barely fit, and upper/lower take down pins barely fit. I never said anything was out of spec, my main concern is tolerance stacking. Of all the lowers I’ve assembled this was the hardest to fit together.
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