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AR Pistol 7.5" Accuracy Problem Login/Join 
No Compromise
posted
I have accuracy 'issues', with my 7.5" AR Pistol. It's a piston driven Sig 516.

Now, I'm not expecting it to be a tack driver. In fact, I'm not expecting it to be accurate at all beyond 100 meters. And, I don't really need it to be.

It's function is to have a short, handy, solution for indoor bumps in the night, and outdoor use just around the house. It provides a bit more bang than a pistol caliber carbine would have. Beyond that, it's a range toy.

It has a momentary flashlight, Vortex 1x-4x PST scope, and SB15 Sig Stabilizing Brace.

A few years ago, it was the Shiz. Now, it's just an oddity I enjoy at the range and next to my bed.

My question: Why does it have the accuracy of a horse shoe? I mean it's all over the place, even at 25 meters scoped. I may as well have a sling shot. At this point, I would get more accuracy picking up a rock and chucking it at an intruder or pest.

Am I expecting more than I should from this AR? Should I have cleaned it rigorously after each shot? Is there some ammunition choice that I should be looking at for this particular set up? What ammo should I be using for such a short AR?

I'm sorry for being so vague about my problem, but I don't even know how to ask the right questions for this. This is my first AR. Someone please give me something I can investigate.

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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Did the problem just develop, or has it been like that since the beginning?

If it just started, check for sight/sight mount or barrel looseness.

If it was like that from the beginning, can you describe how you shoot the gun? What scope do you have on it?

Also, what exactly do you mean by the accuracy is “all over the place” at 25 yards?




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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quote:
Originally posted by sigfreund:
Did the problem just develop, or has it been like that since the beginning?

If it just started, check for sight/sight mount or barrel looseness.

If it was like that from the beginning, can you describe how you shoot the gun? What scope do you have on it?

Also, what exactly do you mean by the accuracy is “all over the place” at 25 yards?


1) I have never gotten great accuracy out of it. It's been that way from the beginning, but I didn't know any better as this is my first AR.

2) The scope has torx screws that are fastened up to 100 Inch-pounds. The rings are set at exactly 60 Inch-pounds per screw (triple screwed rings). The barrel seems tight to me, but I don't know a lot about ARs.

3) I shoot it as I would a bolt gun shooting at bambi in the woods. I have disciplined myself in Stance, Sights (Scope (MOA)), Grip, Trigger, and Heartbeat and Breathing. My training on bolt guns is pretty complete, but that may not translate to AR usage.

4) All over the place means pie plate sizes at 25 yards. And that's from the bench. That can't be normal.

H&K-Guy

ETA: I'm using Independence 55 grn FMJ if that helps.
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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I agree that that level of “accuracy” isn’t normal. That wouldn’t be acceptable for a Hi-Point pistol. My first thoughts would be that either your technique isn’t appropriate for shooting that sort of gun or there is a serious problem with the barrel (even if it’s tight) or the sight.

Without knowing the details of your technique, I can only speculate to some degree, but couple of tips if you’re not doing it this way: When shooting from a bench, the pistol should be rested at two points. The handguard should be placed on something like a sandbag with a soft surface, but which becomes relatively firm when pressure is placed on it. Don’t rest it (and especially not the barrel) on a hard surface. The “brace” should be used like the stock of a rifle and also rested on a similar bag rest. If you can, I’d place the rear of the brace against your shoulder as if firing a rifle.

The most common mistake I see people making when firing an AR is resting the magazine on the firing surface if that’s the only point of rest. It’s fine if the front is supported by a bipod or other sort of rest, but just using the magazine as the only rest and trying to then control the gun with one’s hands may not work well.

And of course the usual advice in these situations is to have another skilled shooter fire the gun if there’s any possibility that it’s due to shooter errors.

If you’re using a good shooting technique appropriate for the gun, then all I can think is that the barrel is seriously flawed or the sight is defective. A very short AR barrel like yours may not produce the same accuracy as a rifle or carbine barrel, but it shouldn’t be far off, especially at short ranges like 25 yards. I would expect to get at least 1-inch groups at that distance with decent (or even not-so-decent) ammunition, including the 55 grain Independence. I don’t, however, have any experience with short-barreled ARs, so perhaps someone else will chime in.

As for the sight, what brand/model is it? Can you remove it and use backup irons?




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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quote:
Originally posted by sigfreund:
I agree that that level of “accuracy” isn’t normal. That wouldn’t be acceptable for a Hi-Point pistol. My first thoughts would be that either your technique isn’t appropriate for shooting that sort of gun or there is a serious problem with the barrel (even if it’s tight) or the sight.

Without knowing the details of your technique, I can only speculate to some degree, but couple of tips if you’re not doing it this way: When shooting from a bench, the pistol should be rested at two points. The handguard should be placed on something like a sandbag with a soft surface, but which becomes relatively firm when pressure is placed on it. Don’t rest it (and especially not the barrel) on a hard surface. The “brace” should be used like the stock of a rifle and also rested on a similar bag rest. If you can, I’d place the rear of the brace against your shoulder as if firing a rifle.

The most common mistake I see people making when firing an AR is resting the magazine on the firing surface if that’s the only point of rest. It’s fine if the front is supported by a bipod or other sort of rest, but just using the magazine as the only rest and trying to then control the gun with one’s hands may not work well.

And of course the usual advice in these situations is to have another skilled shooter fire the gun if there’s any possibility that it’s due to shooter errors.

If you’re using a good shooting technique appropriate for the gun, then all I can think is that the barrel is seriously flawed or the sight is defective. A very short AR barrel like yours may not produce the same accuracy as a rifle or carbine barrel, but it shouldn’t be far off, especially at short ranges like 25 yards. I would expect to get at least 1-inch groups at that distance with decent (or even not-so-decent) ammunition, including the 55 grain Independence. I don’t, however, have any experience with short-barreled ARs, so perhaps someone else will chime in.

As for the sight, what brand/model is it? Can you remove it and use backup irons?


SF,

I'm grateful for your response. I am glad you can confirm that there is indeed a problem.

The pistol has been shot with a 60 rnd Mapgul drum that doesn't reach the bench. I don't make contact with any mag anyway.

It has also been fired with a Harris bi pod attached to the end of the hand gaurd, just for shits and giggles.

I use my shoulder (with the brace) for the third point of contact. I use a shooters bag, or my hand for the front, when I'm not using a bag or Harris.

Another skilled shooter told me last night, "This is the most inaccurate rifle I have ever shot."

The BUIS are standard Sig fare. The scope is a Vortex PST 1x-4X set at 4x. I will remove it and try the BUIS' next time I'm at the range, as per your suggestion.

As per your suggestion, I am also looking closer at the BCG and barrel. The BCG has to spend some time in the Ultra-sonic, then I will go over every part with a fine tooth comb.

Thank you very much for your assistance so far!


H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
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If you've only ever used one type/lot of ammo in the gun, you might try a different brand. Possibly even shell out a few more dollars for one box of premium hunting/defensive ammo and test it with that.

My Dad's first .223 rifle had horrible accuracy with his original ammo. The bullets were tumbling and keyholing through the paper. He talked to the gun shop, and they exchanged his ammo for another brand. Problem went away.


<><><><><><><><><><><><><>
"I drank what?" - Socrates
 
Posts: 5181 | Location: S.A., TX | Registered: July 20, 2006Reply With QuoteReport This Post
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quote:
Originally posted by JAFO:
If you've only ever used one type/lot of ammo in the gun, you might try a different brand. Possibly even shell out a few more dollars for one box of premium hunting/defensive ammo and test it with that.

My Dad's first .223 rifle had horrible accuracy with his original ammo. The bullets were tumbling and keyholing through the paper. He talked to the gun shop, and they exchanged his ammo for another brand. Problem went away.


I will be buying some premium ammo tomorrow. Thanks. Great suggestion.

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
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Also, my B&T APC9 put one ragged hole through the 9 ring at the same range. So my technique should transfer to the Sig 516, no? Please let me know if I am wrong about this.

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Not really from Vienna
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Presumably you are using a bullet weight that is appropriate for your barrel twist.
 
Posts: 26852 | Location: Jerkwater, Texas | Registered: January 30, 2007Reply With QuoteReport This Post
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quote:
Originally posted by arfmel:
Presumably you are using a bullet weight that is appropriate for your barrel twist.


Please presume nothing When it comes to my ignorance!

I can't find twist rates on this AR Pistol on Sigs's site here.

Please help me look for twist rates on this AR Pistol and skewl me on proper ammo. The full size Sig 516 (16 Inch barrel) is a 6-groove, 1 in 7 in twist. Mine should be the same, no?

Thank you in advance for all of you guys' help so far.

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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quote:
Originally posted by arfmel:
Presumably you are using a bullet weight that is appropriate for your barrel twist.


Unless the barrel for some inexplicable reason has a 1/12" twist rate and the shooter is using heavy bullets (which he said he wasn’t), that shouldn’t be the problem. Further, if the barrel twist rate was too slow to stabilize what he was shooting, we would expect tumbling and keyholing, and not merely poor accuracy. With 55 grain ammunition, though, even 1/12" would stabilize the bullets.

It can’t, however, hurt to try different ammunition on the off chance that the Independence is at fault. It’s unlikely, but if, for example, the bullets were grossly undersized, that could cause horrible accuracy. Try some premium quality stuff to rule that out.

Added: According to this, the rifling twist rate is 1/7", and that’s what I’d expect. The twist rate is usually marked on the barrel, but it’s probably under the handguard.




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
No Compromise
posted Hide Post
quote:
Originally posted by sigfreund:
quote:
Originally posted by arfmel:
Presumably you are using a bullet weight that is appropriate for your barrel twist.


Unless the barrel for some inexplicable reason has a 1/12" twist rate and the shooter is using heavy bullets (which he said he wasn’t), that shouldn’t be the problem. Further, if the barrel twist rate was too slow to stabilize what he was shooting, we would expect tumbling and keyholing, and not merely poor accuracy. With 55 grain ammunition, though, even 1/12" would stabilize the bullets.

It can’t, however, hurt to try different ammunition on the off chance that the Independence is at fault. It’s unlikely, but if, for example, the bullets were grossly undersized, that could cause horrible accuracy. Try some premium quality stuff to rule that out.


New ammo will be purchased tomorrow. If, in fact, the barrel is a 6 Groove, 1 in 7 in Twist Rate, like it's 16 inch longer Sig 516 brother, what ammo do you recommend?

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
E Pluribus Unum
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posted Hide Post
quote:
Originally posted by H&K-Guy:
quote:
Originally posted by arfmel:
Presumably you are using a bullet weight that is appropriate for your barrel twist.


Please presume nothing When it comes to my ignorance!

I can't find twist rates on this AR Pistol on Sigs's site here.

Please help me look for twist rates on this AR Pistol and skewl me on proper ammo. The full size Sig 516 (16 Inch barrel) is a 6-groove, 1 in 7 in twist. Mine should be the same, no?

Thank you in advance for all of you guys' help so far.

H&K-Guy

Website cited indicates the barrel is 1:7 twist.

Good luck.
 
Posts: 1407 | Location: Minnesota | Registered: March 05, 2009Reply With QuoteReport This Post
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I have decided, without any knowledge or skill, to try 69-grain Federal Premium Gold match the next time I'm at the range. Anyone disagree???

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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quote:
Originally posted by H&K-Guy:
New ammo will be purchased tomorrow. If, in fact, the barrel is a 6 Groove, 1 in 7 in Twist Rate, like it's 16 inch longer Sig 516 brother, what ammo do you recommend?


Virtually anything would confirm that the accuracy problem isn’t due to a gross manufacturing defect in the Independence. To be most sure, though, try to find some Federal 69 or 77 grain Gold Medal Match. Speer Gold Dot is good, as is Hornady Superperformance Match or even TAP; some of my best accuracy has been with 55 grain TAP. But as I say, almost anything should produce far better than pie plate groups at 25 yards. If that’s what you get with premium ammunition, and you can confirm that the sight’s not at fault, you should contact SIG about warranty work.




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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posted Hide Post
quote:
Originally posted by sigfreund:
quote:
Originally posted by H&K-Guy:
New ammo will be purchased tomorrow. If, in fact, the barrel is a 6 Groove, 1 in 7 in Twist Rate, like it's 16 inch longer Sig 516 brother, what ammo do you recommend?


Virtually anything would confirm that the accuracy problem isn’t due to a gross manufacturing defect in the Independence. To be most sure, though, try to find some Federal 69 or 77 grain Gold Medal Match. Hornady Superperformance Match or even TAP is also good; some of my best accuracy has been with 55 grain TAP. But as I say, almost anything should produce far better than pie plate groups at 25 yards. If that’s what you get with premium ammunition, and you can confirm that the sight’s not at fault, you should contact SIG about warranty work.


Wow. You read my mind! The 69-grain Federal Premium Gold match it is, then.

Thank you all very much for your assistance. I would have been lost without your guys' help.

SigForum members are full of awesome!

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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Keep in mind that whatever you choose for testing may not produce the absolute best accuracy of the loads I mentioned (or of others). If the problem is due to the Independence ammo, then 69 grain Gold Medal Match will demonstrate it, but it’s possible once things get resolved that some other load might be even better in your gun. ARs aren’t like 22 Rimfires in being super ammunition finicky, but I have found differences. A somewhat less expensive load than Federal or Hornady match stuff that’s given me pretty good results is IMI 77 grain OT 5.56mm; I get mine from SG Ammo.




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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quote:
Originally posted by sigfreund:
Keep in mind that whatever you choose for testing may not produce the absolute best accuracy of the loads I mentioned (or of others). If the problem is due to the Independence ammo, then 69 grain Gold Medal Match will demonstrate it, but it’s possible once things get resolved that some other load might be even better in your gun. ARs aren’t like 22 Rimfires in being super ammunition finicky, but I have found differences. A somewhat less expensive load than Federal or Hornady match stuff that’s given me pretty good results is IMI 77 grain OT 5.56mm; I get mine from SG Ammo.


If this is what you mean, I will add this to my list for my next range session! Thanks!

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
Freethinker
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quote:
Originally posted by H&K-Guy:
If this is what you mean, I will add this to my list for my next range session!


That's it. Just don't buy 1000 rounds on my recommendation alone; try it first. Smile




6.4/93.6

“Wise men talk because they have something to say; fools, because they have to say something.”
— Plato
 
Posts: 47365 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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posted Hide Post
quote:
Originally posted by sigfreund:
quote:
Originally posted by H&K-Guy:
If this is what you mean, I will add this to my list for my next range session!


That's it. Just don't buy 1000 rounds on my recommendation alone; try it first. Smile


Big Grin Wink Cool

H&K-Guy
 
Posts: 3720 | Registered: April 08, 2002Reply With QuoteReport This Post
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