My AR DOESNT suck at all! - follow up.

[Plink]

OK, had a most disappointing weekend of shooting. Wildly inaccurate shooting from my rifle. BEST match I had was a 48.1 at the 200, then it went WAY downhill from here. Example. At the 500, aim at v-bull, fire one round, the round hits almost to the top of the 4 ft. I aim at the bottom of the paper, round hits the same spot. I adjust Elcan down a couple of clicks. Next round right at the BOTTOM of the 4 ft. And so it went. Windage was fine, elevation was all over the place. On the saturday, my windage went from dead on to about 1 foot left. This somehow happened from the end of match 5 to the beginning of match 6.
I was thinking Elcan, but TimK pointed out that when I put that optic on his rifle I shot a good group with it.
I've replaced the original compensator with a bird cage (Thanks Hungry), as we thought the compensator was on to tight.

Used 68gr. HPBT out to 300, and 69 gr SMK at the 500.
Rifle is a Stag Arms 1L, 16" barrel.

So, my question, WHAT the heck could be causing this? I have a 60 odd year old M1 Carbine that I can tear a ragged hole in a piece of paper with on iron sights at 50 yards, but my AR won't group better than 4 inches at the same range with the scope.

Signed... Frustrated...........

 

[smak_daddy]

Did you try shooting it with iron sights to completely rule out the scope/mount as the potential problem?

 

[tiriaq]

Try it with a different sight. That eliminates one variable.

 

[Silverado]

I'm not familiar enough with the workings of the AR to offer anything of value here, however;

When it starts sucking DONKEY balls, you have a serious problem.

 

[Plink]

Did you try shooting it with iron sights to completely rule out the scope/mount as the potential problem?

Putting my irons back on it this weekend to test exactly that. Maybe I should hold of on the Donkey ball sucking part until I do that test.

 

[R005t3r]

I had a similair problem with my M1A NM. With 168 SMK it shot 3" at 300 yards and 4" with 147 NATO Porto. I loaded up some 155 Scenars; shot 14" at 300 yards.

I would suggest shooting with irons at 100 yards with various ammo. If it still blows chunks with all of them, well you know what to do

 

[Plink]

Yep, sound advice.

 

[Jarlath]

Barrel Twist rate?

 

[shootemup]

This one sounds like a doozy...send it to me, I'll have to put it through a few years of field testing.

 

[dangertree]

I gotta say, it does sound like the famous Elcan base issue.

If it isn't the Elcan, let me know!

 

[maple_leaf_eh]

The AR has one advantage over the FN, that is both sights are on the top half of the rifle. Although it might be mental trickery, eliminating any play between the halves will undoubtedly have a positive effect on accuracy. Whenever I have had to shoot a good score, I've slipped in an ACCU-WEDGE behind the rear takedown pin. The pointy polymer part squishes on the rear lug.

How's your trigger? Are you using one mag or different ones? The earliest ELCAN C79 sights were notorious for snapping their mounting screws. Others do go out of adjustment - just because. Had one in Bosnia that wouldn't shoot for sour apples for me or the senior wpns tech. Switched scopes and never had the problem again.

 

[mrd49]

I have a similar problem with one of my Garands, but I'm shooting iron. You got good advise about shooting with iron sights to see if the probelem goes away. If its not the scope and your pretty sure your bedding is OK, I think I might check your crown. I know. Pretty hard to ding your crown with a birdcage attached, but stranger things have happened. Just my $0.02.

 

[Plink]

Dangertree, I called and left you a message re this problem this morning. Hopefully you can give me a ring back.

I've thought about the trigger as well. Ordered up a match trigger for it today as the stock one is a bit rough. I might be yanking it and causing the rifle to shift.

TimK also mentioned a possible crown issue. As of right now I think I'll do the following.

Drop in the new trigger when it arrives.

Shoot it with irons to see if it's the Elcan, however, as mentioned, I tried it on Tims rifle and it seemed OK.

Check my ammo. Maybe my rifle just doesn't like my loads.

Get Arms East to check the barrel in case it's really the crown.

Go shoot the next SR match anyways......



Oh, twist is 1:9

Thanks for the replies guys.

 

[beltfed]

What's the muzzle velocity with the ammo you are using?
How is the concentricity?
Have you tried that ammo in another rifle at that distance?
How does it shoot with a barrel with a 1:7 at 500m?
(I have a Sig 1:10 barrel that ran 69 smk fine out to and including 300m, and they sh!t the bed past that)
Is the bore clean? (I bought a slightly used Colt 6920 that wouldn't group 4" at 50m, and had to scrub it down with JB paste before it would group -it was that fouled)
How many rounds through the barrel? (There is no garrantee in a barrels life, just estimates -It might just be done.)

Before spending money on re-crowning, or other re-work of the barrel, factor how much a new one will cost you as a percentage of that re-work. - you could spend 30+% of the cost of a new one on re-working the old one and not fix the issue.

 

[Shelldrake]

So, my question, WHAT the heck could be causing this? I have a 60 odd year old M1 Carbine that I can tear a ragged hole in a piece of paper with on iron sights at 50 yards, but my AR won't group better than 4 inches at the same range with the scope.

Signed... Frustrated...........

Was this your first match?,, and the first time shooting at 500 yards?

 

[sillymike]

If it's not the scope, you might want to remove the flash hider and shoot a few groups.

Seems like there's been cases of over-torked flash-hider causing accuracy problem.

Last but not least, were you shooting reloads or factory ammo?

 

[Plink]

Was this your first match?,, and the first time shooting at 500 yards?

No and no.

 

[Plink]

If it's not the scope, you might want to remove the flash hider and shoot a few groups.

Seems like there's been cases of over-torked flash-hider causing accuracy problem.

Last but not least, were you shooting reloads or factory ammo?

Taking all this into consideration .... Will be working on it on Saturday to eliminate the components.

Who knows.. Maybe I'm the component that needs to be replaced...........

 

[Plink]

What's the muzzle velocity with the ammo you are using?
How is the concentricity?
Have you tried that ammo in another rifle at that distance?
How does it shoot with a barrel with a 1:7 at 500m?
(I have a Sig 1:10 barrel that ran 69 smk fine out to and including 300m, and they sh!t the bed past that)
Is the bore clean? (I bought a slightly used Colt 6920 that wouldn't group 4" at 50m, and had to scrub it down with JB paste before it would group -it was that fouled)
How many rounds through the barrel? (There is no garrantee in a barrels life, just estimates -It might just be done.)

Before spending money on re-crowning, or other re-work of the barrel, factor how much a new one will cost you as a percentage of that re-work. - you could spend 30+% of the cost of a new one on re-working the old one and not fix the issue.

I can't remember what the meter read on the ammo. somewhere in the 2900 range I believe. These were my reloads, 68gr Hornady HPBT and 69gr SMK's.

Haven't tried this ammo in another rifle. Don't have another barrel to try out.

Spoke with Walt this morning as well. The game plan is to do my tests this weekend, sort out what is happening when I'm not on the clock of a match and can fart around a bit, then if I haven't solved it, I'll give him a shout back.

Oh, and the round count is probably in the 4-5000 round area.

 

[Longshot]

Did this combo shoot before or is this the first time its together?
If it shot well before,it sounds like your scope needs an overhaul.My guess is that the post the elevation drum sits on is spinning freely when the drum is turned.I had the exact same thing happen with the exact same symptoms a month or so ago.If it never shot well then you need to start eliminating possibilities.