300BLK

[Bigfoot]

I built my first AR. I did it in 300BLK with a Bear Creek Arsenal barrel. My first outing with it, the thing operated beautifully. Felt good, cycled flawlessly.

Problem is, I could not sight it in. 80 rounds and I could not find it.

It's a 16" stainless barrel with a 1:8 twist. I was firing 124gr S&B ammo.

Is the twist rate too high for the light bullet or is it most likely a junk barrel? I've got some new 147gr Armscor I'm going to try next outing.

Thoughts?

 

[TheAccountant]

What distance were you trying to sight in at? I generally start at 25 and just eye ball it to get close and then move it back to 100. I can't imagine 80 rounds and not even getting on paper... I'm not trying to insult you or anything, but are you sure you were making the adjustments the right way and not backwards?

 

[Bigfoot]

I was at about 40 yards. I would find a hit. Make an adjustment and then it would get worse. Make another, etc. It's not a matter of not finding hits. It was a matter of of getting anything inside of a two foot window.

Guess I should have been more clear. LOL

 

[Steve_In_29]

What were you using for sights...irons, red dot or a scope?

"Got worse"? As in rounds went further away from POA or just weren't getting them to group in a consistent area?

If the former you are adjusting things backwards. If the latter it sounds like something isn't mounted tight.

 

[Bigfoot]

Worse as I was on paper then not. I'd reverse the adjustment and still not find paper. I used primarily a green dot sight. I'll make sure to use both next time and start with the iron.

 

[AZ Husker]

I always start with the irons, then just adjust the dot to sit on top of the front post. You will be very close that way.

 

[Steve_In_29]

What sight were you using? Some of the cheap ones are absolute POSs.

I second The Accountant's, "start at 25yds" approach and suggest a large piece of cardboard as well. That way you can find the impacts even if way wide of the mark.

If you are on paper (no matter how off from your POA) then before touching the sights see if while utilizing the POA you just used, you can shoot a 3 to 5 shot group into the same POI. Do this without readjusting your position or taking your eye out of the red dot between shots. If rounds don't go to the same spot you have mechanical problems.


On edit - You might get more advice if your thread title was more in line with what you are asking about.

 

[Bigfoot]

Will follow the advice I've seen here.

The ammo used was 124gr Sellier and Bellot.

 

[epsilon]

Gonna echo what everybody else has said, start closer and make sure you're turning the adjustment dials the right way. Once you get it close you can push back to the distance you're going to zero at. Get a fresh large target or new cardboard. Then fire a group, same POI regardless of where the rounds hit. I personally like 5 round groups. See how it groups and make a final adjustment or 2 (or if you're like me, like 4).

 

[Harrier]

I always bore sight it, start at 25yds like said and use a known good optic or irons. Make sure everything is mounted properly and screws are tight.

 

[Flash]

As others have said, start closer. Seeing how poorly things were going, I'd start at around 10 yards if I were you, then gradually go back.

 

[zonie77]

Having had similar problems a few times over the years I'll put in my 2 cents.

As said already, get a large target and start up close, no more than 25 ft, with your iron sights. Shoot for groups, aim at a point and shoot 3 or 5 shots and see how small of a group you are getting. Back the target out further and do the same thing. If it's grouping well you know it's probably the optical sight. If it doesn't group up close you know it's the ammo or barrel or combination.

Cheap optics often have poorly finished parts in the adjustment mechanism.. You'll make an adjustment and nothing will happen, then suddenly it jumps way too far.

I was amazed the first time I got a good quality scope and had it sighted in with just 6 shots! A couple of them were because I didn't believe it! LOL

 

[Flash]

How to sight in your rifle with one shot:

Once your barrel and scope are lined up as best as possible, both aimed at the bullseye of your target, you’re ready to get going. Place the bolt back into your rifle, load your rifle with a couple of rounds in your magazine, and get your scope aimed right in the middle of the bullseye. Once you’re ready, and your scope is locked in on the middle of your bullseye just as if you’re about to take a shot while hunting, go ahead and take a shot.

Now that you have a bullet hole somewhere on your target, this is the important part. Aim your scope back at the middle of the bullseye just as it was before you took the shot. In this view in your scope, you should also be able to see the bullet hole you just made somewhere on your target. With the reticle still locked in on the middle of your bullseye, hold your gun as still as possible, use the turrets on your scope to adjust your scope to move the reticle from the middle of your bullseye to where your bullet hole is that you just made. It is ESSENTIAL to keep your rifle completely still while you adjust your scope to move the reticle from the bullseye to your bullet hole.

Once you’ve moved the reticle from the bullseye to your bullet hole, it’s that easy, you’re rifle is sighted in. You have just successfully adjusted your scope to align with the barrel of your gun, a much easier process than the inverse. Go ahead and take another shot or two if you want to confirm this worked, but as long as you held that gun still as you adjusted the scope’s turrets, you should be ready.

 

[Sharky]

I've heard very mixed reviews of Bear Creek with them being on the lower end. With that said follow what everyone said above.
Cheap optics are cheap for a reason. I had a buddy who refuse to pay for "cheap" vortex red dots went with $50 ebay stuff and did not sight in. Heck even his ebay flip BUIS could not sight it and we swapped it on other rifles with the same results.
S&B is decent ammo so I would say check above and go from there with it being your 1st build and all.

 

[Ranger1]

Get a chamber laser, vise, and some full size targets. Lock the vise down on your shooting table. Drop your chamber laser in. Put a target in front of you at 10 ft, one right beside it at 20ft and one right beside it at 30 ft. Bring your sites to the laser at 20ft. Take the laser out ,drop in a round shoot the 10,20,and 30 from the vise. Then note where they are compared to the scope and make your adjustments.

 

[shooter444]

[glow=red]How to sight in your rifle with one shot:

Once your barrel and scope are lined up as best as possible, both aimed at the bullseye of your target, you’re ready to get going. Place the bolt back into your rifle, load your rifle with a couple of rounds in your magazine, and get your scope aimed right in the middle of the bullseye. Once you’re ready, and your scope is locked in on the middle of your bullseye just as if you’re about to take a shot while hunting, go ahead and take a shot.

Now that you have a bullet hole somewhere on your target, this is the important part. Aim your scope back at the middle of the bullseye just as it was before you took the shot. In this view in your scope, you should also be able to see the bullet hole you just made somewhere on your target. With the reticle still locked in on the middle of your bullseye, hold your gun as still as possible, use the turrets on your scope to adjust your scope to move the reticle from the middle of your bullseye to where your bullet hole is that you just made. It is ESSENTIAL to keep your rifle completely still while you adjust your scope to move the reticle from the bullseye to your bullet hole.

Once you’ve moved the reticle from the bullseye to your bullet hole, it’s that easy, you’re rifle is sighted in. You have just successfully adjusted your scope to align with the barrel of your gun, a much easier process than the inverse. Go ahead and take another shot or two if you want to confirm this worked, but as long as you held that gun still as you adjusted the scope’s turrets, you should be ready.[/glow]

The above, perfectly explains the quickest way to get zeroed.

But if I may,... one thing that can help prior to the above, that I believe may make it a little easier/quicker to get to that point,... is,....

First, remove your upper from the lower.

Remove the bolt assembly.

Secure the upper in a vice of your choice, on a table, outside.

Now here is where you need to be creative. View down the bore and move the secured upper so you can place a VERY DISTANT object in the center of the bore. I live in a valley with mountain ranges all around me. I use a sharp mountain peak, any I choose are about 25 miles away, in my valley. A building corner, or a distant tree, whatever you have on the horizon will work.

Now, cautiously adjust you cross hairs to put the distant object in the center of your bore, in the center of your cross hairs.

This is called this BORE SIGHTING,... I have used it for decades, I have used it consistently to the point that I am usually only a few clicks off center bulls eye at 25 yards, which is where I start, on my pistol range.

Next, I measure from center bore to scope objective lens center. I take that measurement and mark a black dot, that distance, below the target's bulls eye center. I place the cross hairs on the bulls eye and make adjustments to get point of bullet impact to hit the black mark.

Now I am ready to move out to my rifle range and start working out to 100 or 200 yards,... which ever I want to do for the caliber I am scoped for.

And now, you can use the perfect advice given by FLASH, above, at this point.

That's all I can add,... good luck!

 

[Ranger1]

In my opinion a chamber laser is faster and that's how I use 2 to 3 rounds to zero everything I have. I will just keep doing what I'm doing.

 

[shooter444]

Well, if your laser quits on you, you may want to consider the above shortcuts that don't use one.

Just say'n.

 

[Ranger1]

I've been trained to zero my weapon without lasers. But when I got out I found that lasers make things much faster. Now laser batteries only go in when u want it to work. So endless I'm out in no mans land I will fall back on my training. When I'm not I will use my lasers. Also considering the laser only has to work for 2 or 3 min. The batteries r good for a hell of a long time.

 

[Harrier]

I have a 16" CMMG 300 BLK barrel and it too is real picky about supersonic loads.
I tried the shotgun approach to finding a load (6 bullet weights & 8 powders - 5 shots each at 25~ 200 yds) and went through 47 different loads. I only found a few I considered marginally accurate enough to meet my expectations...
Since I don't have a can, I never explored subsonic... Needless to say I'm not fond of that cartridge.