1st impressions on BCM upper [Archive]

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Animal_Mother556

08-10-12, 10:11

UPS man arrived on Monday with a 16 inch midlength LW BCM upper for me. Just got back from the range after popping it's cherry.

First of all, zero malfunctions through the 200 rounds. Some Federal M193, some PMP, some PMC. All ran fine (and with an H buffer I might add). It was nice and soft shooting with the .223 especially.

I got it zeroed with a 4MOA Aimpoint and M193. I was not super impressed with the 100 yard groups. My best 5 shot group was 3.5 inches. Having said that, I have never owned a light weight barreled AR or a 1/7 twist AR. It might just be the nature of the beast...dunno. My old crappy Superior Arms upper (16 inch chrome lined 1/9) would do 2.5 inch groups with the same optic and ammo. I need to try some 62 grain stuff, and see what's what.

Also, I ordered a BCM Mod 4 CH with this upper. This is the "new" handle that, I guess, is supposed to cut down on gasses in your face. It does. I had this upper lubed like a mo-fo, and I am used to my glasses being VERY speckled after a magazine. After these 200 rounds, I had about three spots of gunk on my eye-wear. Cool beans.

Overall, I am extremely happy with this upper. Absolutely no complaints. Paul, thank you for a great product.

Some crappy pics --

http://i1118.photobucket.com/albums/k618/AnimalMother_556/BCM5.jpg

http://i1118.photobucket.com/albums/k618/AnimalMother_556/BCM4.jpg

http://i1118.photobucket.com/albums/k618/AnimalMother_556/BCM3.jpg

http://i1118.photobucket.com/albums/k618/AnimalMother_556/BCM2.jpg

http://i1118.photobucket.com/albums/k618/AnimalMother_556/BCM1.jpg

HKBanger

08-10-12, 13:59

I'm running a 16" BCM LW BFH Middy and I've got to say, the accuracy is fantastic. It shoots better than I, no doubt Typically I'm looking at 2.5" or so in groups of 5. Glad you're enjoying yours, though!!

Omen

08-10-12, 15:05

Congrats on the new upper. I have a middy BFH LW and was initially very disappointed in the accuracy of the 55gr rounds I sent through it. However, once I stepped up to heavier bullets it made all the difference in the world.

SRT-M4

08-10-12, 15:14

Very nice weapon. BCM is top notch.
Im a SCAR fan but you cant argue the AR aftermarket and my precision rig is a BCM MK 12 clone.
It shoots .500 to .750 groups at 100 yards and I have taken the gun out to 800 yards with my Accuracy First Wiz Wheel and Black Hills 77 grain Mk- 262 ammo. The gun shot 9'' groups that far out. Very impressed with BCM!

C4IGrant

08-10-12, 15:40

HuttoAg96

08-10-12, 15:59

Just curious, what is the reason for not shooting with a rest? I assume the purpose is to prevent any external forces from being applied to the barrel during the group?

C4IGrant

08-10-12, 16:04

Just curious, what is the reason for not shooting with a rest? I assume the purpose is to prevent any external forces from being applied to the barrel during the group?

Correct. Even with a Free Floating rail and a rest, I always go back and confirm my zero (if zeroing the weapon), but shooting prone, off the mag.

In the classes we teach, I see people with guns that are not shooting where they are supposed to (even when the state that the gun was zero'd). The first question I ask them is if they zero'd the gun off a rest or not. The answer is almost always yes.

C4

kenndapp

08-10-12, 16:12

In regards to ammo, keep in mind that M193/M855 is typically 3-4MOA ammo. On top of that, you are using a 4MOA dot.

Lastly, you might be a 4MOA shooter. :D

Point being, that the group you shot might NOT be the uppers fault.

Get some better ammo a more precise optic and see what you can do with it.

Also, make sure you are not shooting off a rest (use the mag as a monopod).

C4
Can I ask why no rest or bipod?

fallenangelhim

08-10-12, 16:26

I like pretty gun pictures. Good stuff. I think I might want one.

opdsgt

08-10-12, 16:33

Get some better ammo a more precise optic and see what you can do with it. Also, make sure you are not shooting off a rest (use the mag as a monopod).Excellent advice.

Since you're probably not in a position to run out and replace your 4MOA for the sake of shooting @ 100, dial the bloom all the way back on your current optic to the point you can barely see the dot. That and a batch of 75gr Hornady and you should be able to reduce those groups appreciably.

a0cake

08-10-12, 16:59

Just curious, what is the reason for not shooting with a rest? I assume the purpose is to prevent any external forces from being applied to the barrel during the group?

Changes in where external pressures (hands, rests, bipods etc) contact the gun do affect POI. With a FF rail, it's more about pivot and the gun's movement during the firing cycle than force being applied on the barrel.

Case in point - bipod hop. If you don't load a bipod by leaning into it, especially when shooting off of a hard surface, you'll see vertical stringing combined with generally higher POI.

Same with resting the forearm / rail on a hard surface vs a soft one.

You'll also see POI shifts between holding the rifle all the way at the rear of the rail and all the way out front. The rifle simply moves, vibrates, and reacts differently based on how it's being held.

If you want to zero off a rest, the simple solution is to place your support hand between the rest and the gun in the place that it will normally be the majority of the time. Grip the gun as you normally would if there were no rest there and don't use a rear bag. Just use the rest to stabilize your support arm. Using the portion of your arm just above the wrist as a contact point on the rest will ensure that your grip on the rail is the same as if there was no rest there.

The magazine monopod works great also. Some shooters can't necessarily produce groups small enough to get a really refined zero with it, so if that's the case, the above rest method will make things easier and work just as well.

deuce9166

08-10-12, 17:37

whoops double post

deuce9166

08-10-12, 17:37

I have experienced this with m193. Many times I would shoot groups with two or three rounds touching and one or two a couple inches off by themselves. I always chocked it up to shooter error until one night shoot where someone watching me shoot told me that every couple of rounds there would be a more prominent flash from my gun. I figure some m193 rounds may be a little hotter than others.

In regards to ammo, keep in mind that M193/M855 is typically 3-4MOA ammo. On top of that, you are using a 4MOA dot.

C4

trackmagic

08-10-12, 18:01

I'm new here and not as experienced as a lot of you are, but why does it matter if the weight of the gun is sitting on your hand or on a rest or a bipod? It does not seem like it would "bend" the barrel any differently. (The amount of force required to hold the gun up would be the same in all 3 scenarios)

Maybe the difference is after the shot the recoil dynamics are different.

Also, If I ever am concerned about sub-MOA shots (ie aimed long distance) I would probably like to use a bipod or rested on something better than my hand). If I am shooting "off the hip" I don't think I need the accuracy.

I never thought about using the mag as a "monopod". That seems like a good idea. Its always there and would be a good quick support. I'll try that sometime.

skywalkrNCSU

08-10-12, 19:32

I just got done with a build using a BCM upper and the only complaint I have is the front sight post was damn near impossible to remove, those pins were in there TIGHT! Luckily I was planning on shaving it down anyways instead of using a low profile gas block, I just had to do it with it on the rifle (aka, be extra careful shaving it down).

Animal_Mother556

08-10-12, 20:22

Animal_Mother556

08-10-12, 20:23

dial the bloom all the way back on your current optic to the point you can barely see the dot.

Already do that :D

Thanks

Noodles McGee

08-10-12, 20:40

I love mine too. I went 14.5 with a pinned a2x from grant. Couldn't be happier

Also noticed the random fireball with 855.

OP. I like the simple setup

Animal_Mother556

08-10-12, 20:50

OP. I like the simple setup

Thanks, man. I still need to add my light, and rear sight.

Can you add MOE rail sections at the 12 o'clock position?

C4IGrant

08-10-12, 21:22

I never thought about using the mag as a "monopod". That seems like a good idea. Its always there and would be a good quick support. I'll try that sometime.

Not to sound rude (so please don't take it that way), but if you didn't know to use the mag as a monpod, then you need to attend a basic carbine school.

C4

Berserkr556

08-10-12, 21:39

When i bought my first BCM upper, BCM BCG & lower i was very impressed. When i zeroed it and shot it a bunch i couldn't be happier. I even fired some steel cased russian stuff through it and never had a problem. BCM is outeffingstanding !!!

Dirtyboy333

08-11-12, 00:07

Changes in where external pressures (hands, rests, bipods etc) contact the gun do affect POI. With a FF rail, it's more about pivot and the gun's movement during the firing cycle than force being applied on the barrel.

Case in point - bipod hop. If you don't load a bipod by leaning into it, especially when shooting off of a hard surface, you'll see vertical stringing combined with generally higher POI.

Same with resting the forearm / rail on a hard surface vs a soft one.

You'll also see POI shifts between holding the rifle all the way at the rear of the rail and all the way out front. The rifle simply moves, vibrates, and reacts differently based on how it's being held.

If you want to zero off a rest, the simple solution is to place your support hand between the rest and the gun in the place that it will normally be the majority of the time. Grip the gun as you normally would if there were no rest there and don't use a rear bag. Just use the rest to stabilize your support arm. Using the portion of your arm just above the wrist as a contact point on the rest will ensure that your grip on the rail is the same as if there was no rest there.

The magazine monopod works great also. Some shooters can't necessarily produce groups small enough to get a really refined zero with it, so if that's the case, the above rest method will make things easier and work just as well.

Whenever you have the time can you PM me more info on this? Whenever i shoot my MWS from the bench with a bipod (on a hard wood surface) i dont load it at all. I notice that i get the first 2 or 3 shots touching and then the group starts to expand vertically (up). I had thought this whole time that it was my barrel heating up. Thanks

polymorpheous

08-11-12, 00:31

I bought the exact same upper from Grant a few months back.
I installed a H1, 9" TRX, and a PWS comp.

Took it to the range with a forum member to get a solid zero on it.
It shot about the same with PPU M193.

My 16" standard middy from BCM sporting a CompM2, MOE, and A2 actually groups better right now.

I'm attributing this to the blob I see when viewing through the H1.
I don't see this through the CompM2.

Either way, it's a lightweight upper.
I'm happy with it.

a0cake

08-11-12, 00:32

Whenever you have the time can you PM me more info on this? Whenever i shoot my MWS from the bench with a bipod (on a hard wood surface) i dont load it at all. I notice that i get the first 2 or 3 shots touching and then the group starts to expand vertically (up). I had thought this whole time that it was my barrel heating up. Thanks

I'll give you a quick down and dirty here in case anyone else is interested now that it's been brought up. Usually if one person asks a question there are 3 more wondering the same thing. If you have specific questions after this feel free to PM me and we'll take it from there so as to not derail the thread.

But anyway, bipod hop is just erratic, violent motion, where the legs of the bipod are not in the same place before and after firing a shot.

This can lead to a few problems, mainly either lateral or vertical stringing (usually vertical). Another associated issue is having so much movement that your target is no longer in your optic's FOV after recoil has ended. This will cause you to have to reposition, and your groups will open up. You should be able to fire a long string without ever losing your target in your FOV.

There are two main ways to mitigate these issues. First and foremost, center yourself STRAIGHT behind the rifle. This is the core of precision shooting. Getting square behind the recoil is at the center of the whole enterprise. Shooting off a bipod from a bench can sometimes make this difficult. If your shoulders are pivoted and you're using muscle and straining to stay centered, funky shit will happen. Do the best you can to place the centerline, the long axis of your body, directly behind the recoil. This way, the muzzle will move straight back - not up, down, left, or right.

Second - bipod loading. Lean forward into the bipod so that there's positive pressure. On a flat, hard surface, the bipod legs may begin to slip forward on you. Use as much pressure as you can before this happens. You'll find a sweetspot by practicing. A better alternative is to shoot off a loose but firm surface, like packed dirt. This way your bipod can dig in a bit and you can really get a good forward lean. Another solution is to place a sandbag or other heavy object on the flat, hard surface, and just prop the legs up against that and lean forward.

If you can get these two things going for you, any vertical stringing or wandering POI problems that are due to bipod use will go away. ETA: Also, make sure your bipod is placed as far forward as possible.

trackmagic

08-11-12, 01:09

Not to sound rude (so please don't take it that way), but if you didn't know to use the mag as a monpod, then you need to attend a basic carbine school.
C4

Not at all... I have not attended one yet. I actually just got into carbines recently so I am trying to learn all I can.

ALCOAR

08-11-12, 01:23

Another solution is to place a sandbag or other heavy object on the flat, hard surface, and just prop the legs up against that and lean forward.
ETA: Also, make sure your bipod is placed as far forward as possible.

DIY a roll bar at the end of a shooting mat...then load the bipod into the small roll bar. Been doing it for years, works wonders....along with an Atlas of course;)

http://i888.photobucket.com/albums/ac81/trident1982/DSC03660-1.jpg

Dirtyboy333

08-11-12, 01:32

Thanks for the reply. On my 1,000yard bench (table) i stole Tridents idea and screwed a piece of wood down but at my club 100 yard range i have nothing to load against.

Animal_Mother556

08-11-12, 08:38

I know you can't really "break in" a chrome bbl, but has anyone noticed them shooting better over time? After 1000 rounds?

opdsgt

08-11-12, 09:13

My Green Mountain'd 10/22 shoots better if I don't clean the bore, but I don't know if an AR barrel can be "lapped" by shooting it a lot in the same way a rimfire being fed lead round nose can.

My M4's seem to shoot as accurately on a cold bore as they do at the end of an 800 round advanced carbine class. <shrug>

MidwestRookie

08-11-12, 14:43

I'll give you a quick down and dirty here in case anyone else is interested

I appreciate the info, thanks for posting it!