AR Rifles and ammo sensitivity.

[Barnfixer]

I’ve been working with a new AR build in 556 and I’m having some crazy results with different brands of ammo. I know different results from different manufacturers are expected but I’ve never had this happen to this extreme. One brand would be hard pressed to hit a paper plate at 50 yards, another brand has tight groups 100 yards. The gun has a 16” chrome lined barrel if that matters. I’m new to the AR platform and was wondering if this is common. And yes it’s the cheap stuff that shoots poorly but I can’t believe it shoots that bad.

 

[InTheSwamp]

What ammo?

 

[Robert]

The only thing my 20" 1:7 AR doesn't like is 62g ammo. It's still serviceable, but not as good as 55gr. It really loves 77gr match kings...go figure...

 

[Necessary_Nutrient]

The most critical piece of info we need is barrel twist rate, OP

 

[Barnfixer]

Twist is 1:7

 

[Necessary_Nutrient]

It’s hard to reconcile that one brand works that well and another that poorly. I’ve never seen that from a rifle with a properly mounted scope and no barrel installation issues.

In other words, if you’re getting 1.5” or less with quality copper jacketed bullets in a respectable brand name, you should expect 5” or less at 100 (and half of that at 50) from a junk brand or something your rifle doesn’t like, especially with 1:7 which will properly stabilize every and any bullet weight commonly found in 223/5.56 ammo

I would say if you are only getting the dreadful results with one brand, you could have gotten a particularly bad lot.

Checking scope mounting is easy, checking the barrel nut and alignment is more involved

 

[Barnfixer]

Ammo was - cheap brown box stuff by Winchester 55gr, that was the worst. White box Winchester 55gr, better. Hornady black 62gr best. Keep in mind I have to drive a hour for a better selection. I did find some Winchester green tip 62gr I’ll try next.

 

[redneck2]

I’m guessing that the poorly shooting ammo is 52 or 55 grain. 1-7 should handle heavier bullets fine

 

[GooseGestapo]

Ammo was - cheap brown box stuff by Winchester 55gr, that was the worst. White box Winchester 55gr, better. Hornady black 62gr best. Keep in mind I have to drive a hour for a better selection. I did find some Winchester green tip 62gr I’ll try next.

You just named them in order of ascending quality.
milspec FMJ isn’t known for accuracy.
I shoot very little FMJ and the very best is typically 1.5-2” at 100yds. I’ve got some 62gr bulk Hornady’s that over most any powder charge shoot under 1” from every.223/5.56 upper I have. Under 1/2” over 26.0gr of BLC2 from my Wilson/RockRiver NM upper.
Garbage in: garbage out

 

[Barnfixer]

Scope is fairly new and was dead on when it was on my .243 , it’s riding in a new Warne MSR mount. That was double checked along with the barrel nut before my last outing. I think a road trip is order to find different ammo to experiment with.

 

[Barnfixer]

You just named them in order of ascending quality.
milspec FMJ isn’t known for accuracy.
I shoot very little FMJ and the very best is typically 1.5-2” at 100yds. I’ve got some 62gr bulk Hornady’s that over most any powder charge shoot under 1” from every.223/5.56 upper I have. Under 1/2” over 26.0gr of BLC2 from my Wilson/RockRiver NM upper.
Garbage in: garbage out

Best line of the day! Garbage in, garbage out. I’ll have to remember that one. Although in my .243 & 7mm-08 I’ve had some pricey stuff not work as well as the federal blue box or fusion.

 

[C-grunt]

That's odd. Worst I've ever had one of my ARs shoot was about 4-5 MOA with old Wolf steel case. Usually they will do 3-4 MOA with steel case and 2-3 MOA with cheap brass 55 grain.

 

[mavracer]

Best line of the day! Garbage in, garbage out.

And that will be made worse with light weight garbage from a 1 in 7 twist.
That added rpm with bullets that aren't perfectly concentric is a recipe for poor accuracy.

 

[Buzznrose]

My best suggestion is to buy a box of a couple good quality products just to benchmark the results and to ensure you don’t have any issues with the rifle. Stick with 62 grain and above. I’d avoid green tip as it sucks for accuracy. Your rifle should shoot one of these well.

Some suggestions:

20 Round Box - 223 Rem 77 Grain SMK OTM Match Ammunition PMC Ammo - 223XM | SGAmmo.com

SGAmmo.com, bulk ammo sold by the case at the best lowest prices for sale anywhere online

www.sgammo.com

20 Round Box - 223 Rem 68 Grain BTHP Match Hornady Frontier Ammo - FR160 | SGAmmo.com

20 Round Box of 223 Rem 68 Grain BTHP Match Hornady Frontier Ammo For SaleSKU # FR160Product FeaturesConsistency in every cartridgeState-of-the-industry loading techniques and quality control procedures ensure the reliability of every Frontier Cartridge round.Rounds for All ApplicationsFrontier...

www.sgammo.com

20 Round Box - 223 69 Grain BTHP Match Prvi Partizan Ammo - PP57 or PPM2231 | SGAmmo.com

SGAmmo, bulk ammo fulfillment family owned and operated, Stillwater OK

www.sgammo.com

[use default atg pattern]

Black Hills Ammunition 223 Remington ammo for sale at AmmoToGo.com - Don't miss these 50 round packs of 68 Grain Hollow Point ammunition in-stock now.

www.ammunitiontogo.com

 

[C-grunt]

All my ARs are 1in7 except for the precision rifle that's a 1in8. None of them have problems shooting well with 55 grain ammo.

 

[bfoosh006]

I have a Large Frame AR, in 308, that absolutely hates ZQI 308 FMJ ball ammo... shotgun patterns at 100yds.
The same LFAR, will shoot 168gr FGMM 10rd groups under an inch.

It is likely the ammo.

FWIW... I gave up on Winc. ammo being accurate long ago.

 

[tmd16556]

My 1:9 doesn’t like Winchester of any sort, but does like Hornady Frontier (223 but not 556) and steel cased Baranaul. That preference for lower velocity probably is connected to the inconsistent FMJ bullets.

On the other hand, my 30-06 Savage Axis loves Winchester. The cheaper the better for it (Herters 150 gr made by Win, the crimp gives it away).

 

[d2wing]

I’ve been working with a new AR build in 556 and I’m having some crazy results with different brands of ammo. I know different results from different manufacturers are expected but I’ve never had this happen to this extreme. One brand would be hard pressed to hit a paper plate at 50 yards, another brand has tight groups 100 yards. The gun has a 16” chrome lined barrel if that matters. I’m new to the AR platform and was wondering if this is common. And yes it’s the cheap stuff that shoots poorly but I can’t believe it shoots that bad.

I found that the bolt and BCG were binding a little in a PSA build I had that caused erratic accuracy and flyers. A new BCG and Bolt from a high quality maker fixed it. The BCG and bolt must move freely and seat correctly for accuracy. There could be other little issues as well.

 

[CapnMac]

Factory ammo is all over the place. And, price is not necessarily an indication of quality.

And, firearms tend to be individual--what works in this one may not in another. In something of a peculiar anomaly, all of my ARs all currently have 1:7 barrels (if different lengths and makers). Each of them 'prefer' a different brand of factory FMJ. Why? Your guess is as good as mine, but, my primary concern is not the "why," it's in having all the holes close together on the paper in a reasonably predictable way.