SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    Accuracy issues with Sig M400 with ACOG?
Go
New
Find
Notify
Tools
Reply
  
Accuracy issues with Sig M400 with ACOG? Login/Join 
Member
posted
Beautiful day in Virginia yesterday so in addition to my FIL's French MAC 50 (not fired since 1973), I took my Sig M400 complete with a fixed 3.5-power ACOG. Wonderful glass. Great shooter.

Except, using a rest, my first 5-shot group at 50 yards was like 6"! Up down and left-right. Huh. 5 more, same result. And I do the same thing, every time the BEST I can do is a 6" group. 140 rounds total. I'm beyond frustrated. Field & Stream .223 from Dick's from a few years ago.

I ask a friend of my brother's to give it a try. Using Tula ammo non-brass. Which I would never shoot. He immediately shoots a 3-4" group. Not great, but far better than what I managed. I then shoot two 3-4" groups.

What gives? Did I just have a shitty lot of ammo (20-round packs)? I prefer Fiocci 200-round packs for plinking and with that can shoot 1.5 to 2" groups off a rest at 50 yards all day long.

This message has been edited. Last edited by: Batty67,
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
Green grass and
high tides
Picture of old rugged cross
posted Hide Post
sounds like an ammo issue. Can you remove the Acog and shoot with another optic or iron sights?



"Practice like you want to play in the game"
 
Posts: 14988 | Registered: September 21, 2005Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
posted Hide Post
quote:
Originally posted by Batty67:
Great shooter.


If the gun was previously a “great” shooter, how had you shot it before? How many rounds?

Without knowing more about the gun and other elements involved, it’s hard to make specific suggestions, but a few:

Bad ammo. Have you fired the same stuff in other guns? The quality of 223/5.56 ammunition varies widely, and although there’s nothing wrong with shooting the cheap stuff in a high quality gun, such a setup deserves better if we are going to determine its true capabilities.

Problem with the sight. Even the best can fail.

Poor shooting technique. Did you rest the barrel on the support while shooting?

Although unlikely, check the barrel to ensure it hasn’t become loose from the receiver. That happened with a friend’s Colt carbine some years ago. It was totally unexpected, and by the time we figured out what was going on, the receiver threads had been damaged so badly that the receiver had to be scrapped.




“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
— Bertrand Russell
 
Posts: 42486 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Member
posted Hide Post
You don't state the type of ammo other than Field and Stream, which means nothing to me. Never even heard of Field and Stream ammo -- and if it came from Dick's, it's quite likely bottom feeder ammo.

Tula ammo is known for its lackluster accuracy, therefore if it does better than Field and Stream, that's a bad statement for Field and Stream.

Try shooting some better quality if you are concerned about your gun/optic's accuracy. It shouldn't take more than a box of two to find out, if your technique is solid. If you like Fiocchi, try their version of FGMM 69, which uses the same SMK 69 grain bullet. If you prefer lighter bullets -- Hornady 55 Vmax, Hornady 55 HPBT Black, Federal 53 Vmax, Black Hills 55 VMax, Aussie Outback 55 Blitzking. Fiocchi's 55 Vmax isn't a very accurate load.

FYI, accurate loads in your rifle are easily capable of 1/2" to 3/4" groups at 50 yards from a bench with bags.
 
Posts: 6643 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
posted Hide Post
quote:
Originally posted by fritz:
FYI, accurate loads in your rifle are easily capable of 1/2" to 3/4" groups at 50 yards from a bench with bags.


That has been my experience with other medium quality ARs as well.




“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
— Bertrand Russell
 
Posts: 42486 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Go ahead punk, make my day
posted Hide Post
It’s the shitty ammo.
 
Posts: 45798 | Registered: July 12, 2008Reply With QuoteReport This Post
Member
posted Hide Post
Thanks for the input. I should add even, with the 6"+ groups, they were more-or-less centered. Ammo was marked Field & Steam 55 grain .223 FMJ. I got it at Dick's a few years ago. I've shot maybe 1k rounds through my AR, mostly the Fiocci, but a few miscellaneous brands as well. When it had a Vortex Strike Eagle, I could shoot 1 to 1.5" groups. Acog opens it up a bit.

I shot off, as I always do, a carpeted wood block with a U-shaped semi-squishy shooting block on top. 50 m. Rested the barrel. It's a medium quality AR with a high quality, but non-precision Acog (as in, tactical). My technique for this simple exercise should be at least average.

Hope this helps.
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by Batty67:
Ammo was marked Field & Steam 55 grain .223 FMJ.

I shot off, as I always do, a carpeted wood block with a U-shaped semi-squishy shooting block on top. Rested the barrel.

With "rested the barrel", was the barrel itself touching the block or was the handguard/rail touching the block?

55 grain FMJ ammo has never been known for good accuracy. Some brands exhibit adequate accuracy, others are crap.

As with so many forms of shooting sports, technique means a lot to accuracy.
 
Posts: 6643 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
Member
posted Hide Post
Do not let the barrel touch anything as stated earlier, also check to see if your ACOG is properly tightened on the mount and the mount to the rail.
 
Posts: 1465 | Registered: December 03, 2006Reply With QuoteReport This Post
quarter MOA visionary
Picture of smschulz
posted Hide Post
Never overlook the trigger finger either. Frown
 
Posts: 18265 | Location: Houston, TX | Registered: June 11, 2006Reply With QuoteReport This Post
Member
posted Hide Post
The barrel support was resting on the U-shaped rest and the Acog appeared to be on nice and snug. Looking forward to taking it out again and running some high quality ammunition through it. I'm a pretty good shot and, previously, always had good results.
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
I got a Million of 'em!
posted Hide Post
quote:
Originally posted by Super Shooter:
Do not let the barrel touch anything as stated earlier, also check to see if your ACOG is properly tightened on the mount and the mount to the rail.


That’s what I was thinking. We were shooting a buddy’s MPX a few years ago with a 1.5ACOG when the groups were opening up as the mount was coming loose.
 
Posts: 8116 | Location: Hiram, GA. | Registered: October 24, 2007Reply With QuoteReport This Post
Member
posted Hide Post
There is quite a bit that goes into an AR's accuracy.

First, let's get the elephant out of the room. Standard ar's are Minute of Man. IE 1.5 inch capable at 100 yds when in a propper rest using quality ammo.

Expecting more out of a standard AR than that is just really asking a lot.

So, down to accuracy.

There are a number of things on an AR that detract from that 1.5" at 100 yds.

First, is loose optics. The optics may feel tight in the hand, but under recoil it can shift. 1/16th of a fly's ass wisker at the scope is an inch at 100 yds. Be sure you are properly torquing the mount down. 5inch lbs per screw/nut, then 10, then 15, then 20.

Second, ammo 55grain is almost always decent 2-3, sometimes 4 inch groups at 100yds. 62 grain would be better, If it were me I would be looking at 69grain and heavier bullets. I would be looking for quality brass cased ammo to really dial it in.
https://www.targetsportsusa.co...rch=69%20grain%20556
https://www.targetsportsusa.co...h-81268-p-79876.aspx
3rd, your shooting base needs to be consistent. If you don't shoot from that same base regularly, don't expect your best accuracy from it. If you do not have access decent bags, sled, shooting table. then to your best to dry fire practice with the same set up you will use at the range, including how you sit.

4th, you may very well have a loose part other than the scope. IE barrel nut, or flash hider/brake. Take some time and walk through and check everything out.

Now for my guess. It is the ammo combined with the shooting set up. If I am sighting an AR platform in, I do it with a 10 round mag, and bags, on my shooting bench. I keep all of that consistent. I hope that helps.
 
Posts: 6092 | Location: Virginia | Registered: December 23, 2010Reply With QuoteReport This Post
Member
posted Hide Post
Thanks DSgrouse. I'll try to systematically check the variables against the outcome.
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by Batty67:
The barrel support was resting on the U-shaped rest...

I'm a pretty good shot and, previously, always had good results.

"Barrel support" is a rifle part or some terminology that I'm not familiar with.
Was any portion or surface of the barrel touching your u-shaped block? Or any other block or device?

Was the only device touching the u-shaped block the handguard / rail / tube-like-thingie surrounding the barrel?

What were you previous good results? i.e. group sizes at various distances to targets
 
Posts: 6643 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by fritz:
quote:
Originally posted by Batty67:
The barrel support was resting on the U-shaped rest...

I'm a pretty good shot and, previously, always had good results.

"Barrel support" is a rifle part or some terminology that I'm not familiar with.
Was any portion or surface of the barrel touching your u-shaped block? Or any other block or device?

Was the only device touching the u-shaped block the handguard / rail / tube-like-thingie surrounding the barrel?

What were you previous good results? i.e. group sizes at various distances to targets


Hand guard around barrel cradled. No actual barrel (metal) touching the rest. At 50m same set-up, I could shot 1-2" groups (good day closer to 1"; less good day more like 2"). The day I was talking about was 6+"
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
Moderator
Picture of arcwelder
posted Hide Post
Can we pretend to care about spelling? Just in the title?


Arc.
______________________________

"Like a bitter weed, I'm a bad seed"- Johnny Cash

"I'm a loner, Dottie. A rebel." - Pee Wee Herman

Rode hard, put away wet. RIP JHM

"You're a junkyard dog." - Lupe Flores. RIP

 
Posts: 26607 | Location: On fire, off the shoulder of Orion | Registered: June 09, 2004Reply With QuoteReport This Post
Member
posted Hide Post
And I'm a writer-editor. Really.
 
Posts: 2955 | Location: Alexandria, VA | Registered: March 07, 2011Reply With QuoteReport This Post
  Powered by Social Strata  
 

SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    Accuracy issues with Sig M400 with ACOG?

© SIGforum 2020