Practical accuracy expectations from a 16" gas gun

[schüler]

I think the 1 MOA guarantee is a bit like the Ransomware Free guarantee. Silly, ridiculously unrealistic, and misleading.

Some manufacturers build a reputation on that (or better) and deliver it 99% every day.

[Backspin]

I stumbled on this thread on Sniper's Hide: https://forum.snipershide.com/forum/...et#post6438046

Post #14 by Elfster1234 seems particularly germane to topic at hand.

[frozentundra]

I've recently transitioned from a 1-4 on my 16" AR to a quality 2.5-10. The barrel is a medium contour 5.56 chamber and floated.

With the new optic and my current commercial 77gr selection I'm reliably getting 1.5-2MOA at 600 yards and usually similar results at 100. Part of me suspects that me + the optic exceed the capability of the rifle.

I have a few questions for those more experienced than me:
1. What's a reasonable accuracy expectstion for a gas gun and 5.56 chamber using match ammo?
2. How important is having sub-MOA accuracy when engaging small targets out to 600 yards? I'd call 1-2 MOA a small target.
3. What is the path to greater accuracy? New barrel? Better ammo? What are the recommendations for barrels these days? Hand loading is not an option.

I'm measuring accuracy as 5 and 10 round groups. Sometimes fired from a bench, sometimes prone with a sling and or rest.

Also- I've noticed that my 100 yard groups are frequently less impressive than 200 or 300. Has anyone else seen this before?

I've recently been bitten by the precision marksmanship bug, but don't have unlimited thousands to spend, so I put together a budget/starter package with a Savage Fcp-sr in 6.5 Creedmoor, SWFA fixed 10x scope, Harris bipod, and Seekins Precision rings. I had some encouraging results, but not as consistent as I could have hoped, so I undertook to figure out what I was doing wrong.

After a bunch or reading, I settled in on Todd Hodnett(Accuracy 1st) and Bryan Litz(Applied Ballistics) as two credible sources of information, who are on the progressive, leading edge of the industry right now. So I started reading a bunch of their material and listening to freely available, in-depth podcast interviews. Both of these guys seem genuinely happy, eager even, to freely disseminate information and are wonderful podcast interview subjects. There is a treasure trove of interesting and nuanced information available in podcast form. Just a few that I have easily to hand are:

Precision Rifle Podcast numbers 46, 63, 89.
Precision Rifle Media numbers 04, 09.
Precision Shooting Podcast number 17.

A few takeaways that I found helpful, interesting, and seem perhaps relevant to your situation are as follows:
...................
#1
If you don't have a bubble level on your scope, it's very hard to achieve repeatable accuracy. The human eye/brain is not great at getting inside of 3 degrees of level(to the fall of gravity) consistently, especially in natural environments, where no level man-made structures exist in your field of view. If you are holding a crosshair in very consistent relationship to a gridded target it might not factor in at 100 yards, but if using a horseshoe, dot, or similar reticle, or not paying very specific attention to this factor, it could be a small contributing factor. It certainly comes into play at longer ranges and both men consider a bubble level mandatory for anybody wanting repeatable accuracy in the field. Bryan Litz has taken to saying he can make people better wind callers in the first 30 seconds of his class, he simply starts off with, "buy a bubble level".

#2
In Precision Rifle Podcast 63, Bryan Litz talks about the strange and prolific phenomena of nonlinear dispersion of groups. Most specifically, when people seem to exhibit better accuracy(in terms of angular measurements) at farther distances of 200, 300 or 400 yards, as opposed to the traditional 100 yard "sight-in" distance. The urban legends that pop up around this phenomena are legion, and Brian has actually developed methods to study it, finding no empirical proof when measured in a quantifiable scientific manner. He actually has a standing offer to pay all travel expenses for anybody who has a rifle/ammo combination that will consistently exhibit the phenomena, to come to Applied Ballistics lab to study it. His tentative hypothesis seems to be that there are other factors at play, likely a combination of optical sighting phenomena, mental focus and other shooter-related factors. This is highly related to my next takeaway.

#3
Parallax and scope shadow. Especially if you are using a 1-4 optic without parallax adjustment(or even a parallax adjustable 10x) it is absolutely critical to have your eye placed DIRECTLY in the center of the scope. Every. Single. Time. Traditional wisdom says we should build up a solid, comfortable, repeatable cheek weld, with the largest "full field of view" possible, totally eliminating the hated scope shadow. This may actually be suboptimal for maximum precision. In many of the aforementioned podcasts, Todd Hodnett talks about using scope shadow as the only tool we actually have to achieve precisely centered eyebox placement, thus eliminating as much parallax as possible from the shooting equation. You can move your eye rearward until a thin ring of scope shadow appears around the edge of the field of view. Now you can either try to move that fraction of an inch back toward the scope in order to reacquire that full field of view that everybody wants to see(without loosing placement), or, better yet, go ahead and shoot with the constant feedback from that tiny ring of scope shadow allowing you to place your eye DIRECTLY in the center of the scope. Todd talks about how he personally stumbled on to this technique, accidentally, while shooting heavy recoiling rifles, and how the veracity of it has only been reinforced by discussions with optical engineers who have multiple doctorate degrees in the field.

...................

By implementing the above information I was instantly able to shoot 3/4 minute or tighter groups, several of which were sub 1/2 minute, using factory Hornady ELD-M ammunition from rear bag supported prone position, at 100 meters, with a $600 rifle and $300 scope. Now I need to move my scope further forward in the rings to allow me to get the correct eye relief to utilize scope shadow without straining my neck backwards. I had placed it to allow me the maximum field of view, to include seeing the most of the inside of the scope tube possible, for some reason.

I encourage anybody who wants to try this technique to listen to some of those podcasts and get the story straight from the horse's mouth(Todd Hodnett), instead of sumdude on the internet with a cheap Savage rifle who tried it once.

[frozentundra]

Also, make sure you understand the nuances of diopter adjustment and parallax adjustment. Without precise and correct adjustment here, it doesn't matter if you have a $10000 rifle, $5000 scope and the world best ammo, you can still have issues that are easily avoidable with some simple knowledge.

But beware, the internet is chock full of stupid advice by people who parrot "conventional wisdom" and it is easy to be mislead.

[NH Shooter]

I've recently transitioned from a 1-4 on my 16" AR to a quality 2.5-10. The barrel is a medium contour 5.56 chamber and floated.

With the new optic and my current commercial 77gr selection I'm reliably getting 1.5-2MOA at 600 yards and usually similar results at 100. Part of me suspects that me + the optic exceed the capability of the rifle.

Could be. I have owned four different BCM uppers, two of which were the regular medium contour and that is about what I got out of mine.

The most precise was a heavy barrel 1/8 twist 16" SS 410, which was capable of sub-MOA with good ammo. Unfortunately, I didn't pay attention to weight with that build and ended up with a 10+ pound "carbine."

My current "lightweight" carbine (7.5 pounds) uses a 16" BCM ELW BFH mid length upper and with most ammo stays in the 1.2 to 1.5 MOA range. In fact with .223 Speer Gold Dot 75 ammo, it typically puts four in a 3/4" group at 100 yards and the fifth opens the group to just over one inch. For the weight and ease of handling - and the terminal effectiveness of that load - I find it very much meets my expectations.

[Sensei]

I've recently transitioned from a 1-4 on my 16" AR to a quality 2.5-10. The barrel is a medium contour 5.56 chamber and floated.

With the new optic and my current commercial 77gr selection I'm reliably getting 1.5-2MOA at 600 yards and usually similar results at 100. Part of me suspects that me + the optic exceed the capability of the rifle.

I have a few questions for those more experienced than me:
1. What's a reasonable accuracy expectstion for a gas gun and 5.56 chamber using match ammo?
2. How important is having sub-MOA accuracy when engaging small targets out to 600 yards? I'd call 1-2 MOA a small target.
3. What is the path to greater accuracy? New barrel? Better ammo? What are the recommendations for barrels these days? Hand loading is not an option.

I'm measuring accuracy as 5 and 10 round groups. Sometimes fired from a bench, sometimes prone with a sling and or rest.

Also- I've noticed that my 100 yard groups are frequently less impressive than 200 or 300. Has anyone else seen this before?

The Noveske SPR build with NF 2.5-10X pictured in post #683 here:

https://pistol-forum.com/showthread....Gallery/page69

Will do this:


...all day long with factory SSA or BH 77 grain Sierra OTM. That 0.68 MOA 5-shot group was shot unsuppressed from sandbags at 100 yards last weekend.

The specs for this rifle are as follows:

Limited Edition, 18" SPR 5.56mm Rifle with VIS, Flat Dark Earth

--18" SPR 5.56mm stainless barrel, 1 in 7" twist
--Vltor VIS 12" monolithic upper
--Extended Feed Ramps
--Beadblasted finish on barrel
--1/2x28 threads
--Vortex flash suppressor
--Intermediate length gas system
--Geissele SSA two stage trigger
--Shot peened and MP tested bolt
--Properly staked carrier key
--Auto carrier
--Mil-Spec receiver extension, staked
--H Buffer
--Vltor E-Mod buttstock
--Tango Down pistol grip
--Six Tango Down SCAR rail panel covers
--Noveske QD receiver end plate sling mount
--One 30 rd mag included
--Low-profile gas block pinned to barrel
--Flip-up front and rear sights
--V-TAC Sling, Khaki
--Eagle discreet LE case, with Noveske Logo
--ADM 30mm Recon scope mount, Tan
--Two QD sling swivels
--MI 1913 Heavy Duty Sling mount

[Sensei]

Edit to the above post - the Vortex flash hider has been replaced with a SF3P-556.