Frustrating day with my 11.5 inch upper

[Dr.Rob]

Had a great day with my competition rifle but my 11.5/5.5 XM upper was dismal.

Yes, it went bang every time but I could not get on paper at ALL at 50 yards with a B-24 target.

I put an orange dot sticker in the center of the target and and nothing. I held at the top and the bottom of the target and nothing. Never got a hit on paper, nor on either side of the target I could see.

I wasted a box and a half of ammo before setting it aside. I deduced I was shooting over or under the target.

I checked the bore with a laser when I got home, suspecting my front sight was too high. I cranked it down a full two rotations (8 clicks) while I have a very slight deflection to the right the laser is about where you would expect, 2.5-3 inches below the sights at across the room distance.

I am clueless.

Need to find a 25 yard range and start over. I am a decent shot and that made no sense.

 

[Snyper]

I'd give it a good scrubbing, check all mount connections for proper torque, then try at 25 yds

Was it a load you've had good results with before?

 

[HexHead]

Take the upper off and bore sight old school, looking down the bore.

 

[Dr.Rob]

No mounts to tighten.

A1 upper and sights.

Same day, same rounds, with a different rifle was having great results.

It has a plastic lower on it currently, that will change soon. The idea was to build a very lightweight carbine, it weighs about 6 pounds right now.

 

[Holescreek]

Do you have the luxury of a range where you can start close to the target and walk it back taking a shot every couple of yards? Lasers, even chambered ones will only get you close, meaning 8" or so on a good day.

 

[Blade First]

Ammo...unless you have a misaligned 'whatever' that involves bullet strike.

You're way too good a logical thinker to ignore the possibility. Are you sure that your ammo was reasonably consistent?

The idea that a particular barrel, especially at that length to target, would be so defective is hard to fathom.

Please let us know what you find.

 

[Dr.Rob]

Ammo was PMC XTac 55 gr. Was getting near 1 inch 100 yard groups with same ammo in my other rifle.

http://www.thehighroad.org/showthread.php?t=778877

 

[WestKentucky]

I had a lot of trouble with a .17 hmr which seemed to be throwing curveballs, and a 9mm that actually was throwing curveballs. Start close and work it out. 5 yards, then 7, then 10, 15, 20, 30, 50, 75, 100. At 5 yards if your not hitting paper you have major problems. If you can't follow the bullet working your target out you have major problems. Sometimes it takes extreme measures to figure out something that seems so crazy is actually pretty simple.

 

[MistWolf]

Sometimes, the answer is as simple as shooting into a dirt bank

 

[readyeddy]

If it's bore sighted across the room, you can rule out the alignment of the sights.

If the ammo worked in your other gun, you can rule out the ammo.

That leaves the rest of the gun. What could affect accuracy?

The crown? Bore? BCG?

 

[jerkface11]

Sometimes, the answer is as simple as shooting into a dirt bank

That's how I start out when sighting anything in.

 

[H&Hhunter]

Sometimes, the answer is as simple as shooting into a dirt bank

I do that all the time..Saves time and money.

 

[Dr.Rob]

I was at Cherry Creek, they frown on shooting their rail ties.

I hope it's not the crown I paid a pretty penny for this barrel.

 

[jerkface11]

Even if it is the crown that's fixed pretty easily.

 

[MachIVshooter]

I hope it's not the crown I paid a pretty penny for this barrel.

Probably not, but if it is, we can drill that FH pin out and reface it.

I've had plenty that I thought were decently laser boresighted and weren't on paper at 50. Those boresighters work pretty well on a bare muzzle, but not so much with some flash hiders.

 

[benEzra]

If it's bore sighted across the room, you can rule out the alignment of the sights.

Depends on how precisely it is boresighted across the room, the size of the room, and how far away the target on the range is. If the rifle is boresighted indoors at 10 feet and the target is 50 yards away, the aiming error will be multiplied by fifteen...so every inch of error at 10 feet becomes 15 inches of error at the target.

With an 11.5", muzzle climb during recoil may also cause some discrepancy between boresight and point of impact, which might be significant if the rifle was sighted high to start with.

 

[Blade First]

"If the ammo worked in your other gun, you can rule out the ammo."

Well, no...you *can't* rule out the ammo. Why would you think that you can ignore a major variable simply because it goes 'bang' in both uppers?

Which is more likely...that there is a significant flaw in the chamber, barrel or flash-hider/compensator of the non-grouping upper or a significant variance in the same ammo used?

As someone who has tested hundreds of uppers, I personally don't think that the ammo selection in a different upper is a problem, but you cannot simply dismiss the possibility.

 

[Holescreek]

Is there anything inside that extension that the bullet could be grazing on the way out or is it a big hollow tube with flash hider slots and an open end?

 

[stolivar]

better start with a 25 yard target

I had the same problem and was shooting way to high. go to 25 yards and shoot it with the same setup as a ar15. you should be shooting around 2 inch low at 25 to get you on the target at 50.....


steve

 

[Dr.Rob]

No copper residue in the flash hider, it's a big hollow tube. The bore is nice and shiny no defects. Bolt carrier has no difference in 'slop' with the upper removed complete than my other two AR's, a Colt and a Model One. Everything lubed up properly.

 

[readyeddy]

You have a bore laser so try to bore sight 50 yards. Maybe install a scope just to check the gun.

At night shoot the laser at a next door building about 50 yards away and place the reticles on the dot. If you paint the laser a longer distance then even better. With this you should have no problem hitting paper at 50 yards.

If your gun groups with the scope then the gun is good and you just need to align the iron sights.

 

[joneb]

Maybe not enough twist? A friend has a 11.5" 300 BO with a 1:8 he has trouble with 220gr, his dad has the same with a 1:7 and it does fine.

 

[Dr.Rob]

Taking it to Pueblo West tomorrow, a few shots in the dirt should suss out whats up.

 

[Dr.Rob]

25 yards iron sights three shots one hit the right edge of the target. o I was missing wayyyy right, and high.

Eight clicks left, got near the shoulder.

Eight more clicks left and still not on center. Rear sight is now almost out of windage adjustment.

Forgive my shooting it was cold rainy and I had already shot a match and was mono-podding off the pistol grip.

Ammo is the same PMC I shot during the match.

Justin suggested I could have the barrel not torqued right or I have a bad barrel I hope it's the former and not the latter.

Any thoughts are welcome.

 

[Hardtarget]

First shots with my AR scared me. I had to adjust as far as it would go to the left just to touch paper. So, I went home and made a spacer to put under the left side of my rear sight. Next shots needed to move the sight almost back to center of sight body...and we were zeroed. I'm happy now.

I hope you can get this ironed out.

Mark