New To Semi-Autos

[Wolf762x51]

I decided I wanted a lighter-weight precision platform since I live in New England and long sight lines are scarce at best, especially since my .308 is a 18lb beast of a rifle. I put a 16" 1:7 Green Mountain barrel on my upper and grabbed some Fed GMM 77gr match loads and went to the range. I know the GM isnt a match barrel, but getting 3 MOA groups that wander at 100 seems less than the rifle should perform. Im not a pro shooter by any stretch and im 110% sure most of that is me. The question I suppose Im asking is; what should I expect from a platform such as this? I figured 2 MOA is more than enough for man size targets at 800yd and in, but Id definitely be happier if me and my system were more accurate. Thoughts? Everything is appreciated and thanks in advance folks.

 

[RTV]

What?
are we talking about a .308 or an AR15 in 5.56?

its not unrealistic to expect 1 MOA or even less from a high quality Semi auto these days.
the military specs the MK12 as a 1 MOA rifle as the MINIMUM. if that means anything to you.

 

[Wolf762x51]

Sorry, its just my personal AR15 in 5.56. Topped with a Vortex Strike Eagle 5-25x

 

[Carlos0311B4]

I have a FN Tac2 with a gov profile chrome lined barrel that will shoot just under 1” with quality ammo.
I’m not familiar with GM but I would say it should be more accurate than that. I’ve also had a BCM that would shoot just about anything around 1 moa. My wife’s first time out at 500meters / 546 yards. She shot a 7” shot group with 77g and the BCM.

who built the rifle? Did they play legos or do they know what they are doing?

Look up Malon’s post in SOCOM barrel accuracy

 

[Wolf762x51]

I have a FN Tac2 with a gov profile chrome lined barrel that will shoot just under 1” with quality ammo.
I’m not familiar with GM but I would say it should be more accurate than that. I’ve also had a BCM that would shoot just about anything around 1 moa. My wife’s first time out at 500meters / 546 yards. She shot a 7” shot group with 77g and the BCM.

who built the rifle? Did they play legos or do they know what they are doing?

Look up Malon’s post in SOCOM barrel accuracy

The rifle started life as a Smith M&P15, just upgraded trigger, new barrel and handguard. Nothing special.

 

[Carlos0311B4]

The rifle started life as a Smith M&P15, just upgraded trigger, new barrel and handguard. Nothing special.

Did you build it?

 

[Wolf762x51]

No. Local shop threw the parts on.

 

[Carlos0311B4]

Do they specialize in AR’s? Or are they a general smith? Even some so called specialty smiths are a no-go

Not to be a dick but, most of the time build a budget gun, get budget results.

look up:
School of the American rifle (YouTube)
Ar build junkie (hodge defense interviews, SOLGW, BCM interviews)
Trajectory arms

They do a better job of explaining how things should work.

 

[Wolf762x51]

Thats not being a dick, its what I need to know. Next move will be to a Douglas match barrel, well see if that improves things.

 

[Carlos0311B4]

Have you herd of School of the American Rifle?

if you havnt you’re going to thank me later...and hate me...you’ll see what I mean.. lol

 

[tuckybill]

Go to compass lake engineering web page and get the Douglas ready to ship barrel. Go to fleabay and get some Loctite 609 retaining compound. Go to Larue and get the MB2 trigger. Take the GM barrel out. Glue in the CLE barrel. Don't worry about ever getting it apart just toss the whole kit and kaboodle when the barrel is shot out. Everyone with a AR should have a spare upper or three. Put in the Larue trigger, no its not a Geisslie Hi speed but its the best value out there.

Now you have a 1 MOA ar. Oh and you'll need some GOOD ammo. Putin's pew pew won't shoot MOA. Oh and don't do like all the guys on ytube and test it in 20 mph winds.....

 

[Wolf762x51]

Go to compass lake engineering web page and get the Douglas ready to ship barrel. Go to fleabay and get some Loctite 609 retaining compound. Go to Larue and get the MB2 trigger. Take the GM barrel out. Glue in the CLE barrel. Don't worry about ever getting it apart just toss the whole kit and kaboodle when the barrel is shot out. Everyone with a AR should have a spare upper or three. Put in the Larue trigger, no its not a Geisslie Hi speed but its the best value out there.

Now you have a 1 MOA ar. Oh and you'll need some GOOD ammo. Putin's pew pew won't shoot MOA. Oh and don't do like all the guys on ytube and test it in 20 mph winds.....

I have a Geissele 2 stage in already but thatnks for the reccomendation

 

[Slevin182]

Definetely too big a group if you're doing your part. Scope mount/rings tight?

 

[Wolf762x51]

Definetely too big a group if you're doing your part. Scope mount/rings tight?

Yes, rings were done correctly and with a torque wrench. Cantilever base was done "good n tight" with a torx allen.

 

[tuckybill]

Hmm.......should beat that. GM barrels arn't the greatest but they should be 1.5 inch at 100 yrs with that scope,trigger, good ammo on a still day. uhhhhh.....have you had someone else shoot it? Do you wear good hearing protection? Could be a flinching issue. That sneaks up on us all and is hard to get rid of once you get it. <------like a lot of things in life.

 

[Wolf762x51]

Hmm.......should beat that. GM barrels arn't the greatest but they should be 1.5 inch at 100 yrs with that scope,trigger, good ammo on a still day. uhhhhh.....have you had someone else shoot it? Do you wear good hearing protection? Could be a flinching issue. That sneaks up on us all and is hard to get rid of once you get it. <------like a lot of things in life.

It very well could have been me. First two boxes of ammo through it did 1.5 or better at 100. The next trip was like night and day. 2.5-3" groups and they shifted all over the place

 

[Greg Langelius *]

I agree with one thing (at least) out of all the above; get someone else's eyes behind the sights and see how they do with the gun. In times of trouble, two sets of eyes are nearly always better than one. The likelihood of both of you being shaky shooters is not impossible, but it's a lot less.
There's no need to make this more complex than it has to be.

Next try same varmint ammo, 50-55gr or thereabouts, or 69gr FGMM, and see if the problem continues. If so, the barrel becomes far more suspect, especially if it's still doing the bad things with that other shooter. It may be something as simple as the barrel being mismarked regarding twist. For the clincher, try borrowing another, proven Upper, and seeing how it compares.

It's the wandering zero that has me baffled. It could be a barrel mounting issue, a floating barrel or gas block that's making contact with something rigid (like the handguard), a scope mounting or internals problem, or something as simple as an inconsistent cheekweld.

Also examine the crown with some moderate magnification to rule out any jagged damage at the juncture between the bore and the muzzle face.

Also along those lines, if here's a muzzle brake, especially a new, separately mounted one, that's a possible source of brake baffle strikes. Examining the inside surface of the brake exit should exhibit strange marks on the muzzle's interior surface if strikes are occurring.

Finally, does the fired brass look strange....?

Greg