New Barrel (AR) Not Grouping With Factory Ammo

[RangeRat83]

Hey All,
So, I recently assembled a new rifle and can't get it to group... It is 1:7 5.56. I took it out twice since building. First trip I only used factory 5.56 Hornaday Frontier to try and sight-in and was getting 4-5 inch groups at 50 yds. The second trip I took another rifle and some hand-loads. This time the factory and hand loads grouped about the same (1/2-1 in) at 50yds. However the rifle in question grouped about 1 inch with the hand loads with now flyers or any other trouble. I was wondering if anybody else has had this happen to them? I'm hoping that this is just a matter of a "break-in" period and that the groups will tighten up. Both barrels are 16in 1:7 twist shooting 55gr ammo. Anything helps. Thanks.

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[v0lcom13sn0w]

try a heavier bullet. generally, 1/7 likes the heavies

 

[monkeybutler]

...

 

[Member 34319]

Some guns just don't like the same stuff another similar gun do. I can't tell you why, it's just the way it is. Keep trying out different things and you will likely find something that works.

 

[P7M13]

What's your optic / or sights?
Torque everything to spec?
First build? If not, how many have you done?
Gas block tight?
Did you check head space?
What's the chamber look like?
How tight (or sloppy) is the round when seated in the chamber?
Muzzle device? Screwed on or pinned? Tight (i.e. you cannot wiggle it by hand) ?
Any damage to the crown?
Are the primer strikes all concentric and consistent?

I'd
Check you torque settings
See if you can wiggle anything
Verify your alignment of the upper receiver and the handguard.
Check you optic mount
I'd remove the muzzle device if not pinned and re-test with that left off.

 

[Kruel J]

try a heavier bullet. generally, 1/7 likes the heavies

This. Try some 68-75 grain projectiles.