Is bulk 223/556 junk

[tug]

Helping a buddy with his AR and the best group we can get is about 3.5-4.5" at 100yds using bulk green tip ammo. New match grade trigger, lapped the rings, and even replaced the 18" barrel. Rings are tightened to spec using torque wrench. Still crap groups. Got to looking at the ammo and some of the cases have small dents and other irregularities. I'm not an AR guy but this rifle SHOULD shoot better than this.
Borrowed another AR and we are getting about the same groups using the same bulk green tip ammo.
Assumption...... bulk green tip ammo is inconsistent at best, crap at worst.
Any suggestions on the next step? Other things to check?
Suggestions on readily available 556/223 varmint ammo that is on the cheap end? All I could find at Academy that wasn't FMJ was $52 for a box of 20 and he is cheap and won't pay that
Original plan was for this to be a SHTF gun, but now he wants to shoot some coyotes with it.

Let me see if I have this right. Instead of buying $30 worth of quality ammo to check this rifle to begin with, a new trigger was bought and installed, and a new barrel bought and installed, and then test fired with the same ammo.

Do I have that right?

 

[double browtine]

It's the ammo. Deer Assassin (Lade)sent me some hand loads when I couldn't find any a couple seasons ago for my kinds to hunt with. When I shot them, I thought I had missed the target on my second attempt. When I shot the 3rd round and checked the target there was an oval hole for 3 shots at 75 yards. That was using an Anderson mil spec upper and lower with a drop in 3.5 lb trigger. Good hand loads are amazing!

 

[hammer33]

Let me see if I have this right. Instead of buying $30 worth of quality ammo to check this rifle to begin with, a new trigger was bought and installed, and a new barrel bought and installed, and then test fired with the same ammo.

Do I have that right?

Totally out of order if you ask me except for the absolute garbage trigger it came with. That thing had to go.
I make a suggestion, he wants to do something else, so I get to play with a new AR platform on his dime.

"my AR sucks can you help me"
Sure, lets check.....
"I got a new trigger"
Ok. Lets put that in.
"still shoots like crap"
Ok Lets try.......
"Can you install the new barrel I got in yesterday? "

 

[sneakybow]

Tighten up the loose nut behind the trigger lol

 

[44 mag]

You said that you replaced the barrel. Make sure you have the barrel nut torqued to spec also. Not sure I seen anyone mention that.

 

[BuckWild]

May want to refer to this chart...