HELP accuracy issues!!!

[Blinds]

Hey guys just joined the forum. Hope I don?t sound like a complete idiot.
Anyways Have built a few ar15s but built my first one chambered in Grendel 2 years ago using some new parts and some parts I had laying around.
Anderson lower
Smith and Wesson mp no forward assist no dust cover upper
Alexander arms light 16 inch barrel and Alexander arms bolt.
WMD bolt carrier
Jp adjustable gas block
Vltor rail
Idk if you guys need to know any of the other parts I used or not? Anyways this build put 5 rounds inside a nickel at 100yds with factory Hornady ammo.
I didn?t like the no dust cover look and bought an Anderson upper with FW/dust cover. Got a wmd nickel boron Coated upper kit. And got a new seekins rail and also changed out the gas block for a non adjustable aero Precision gas block all the other parts are the same. This build will put 5 rounds inside a baseball at 100yds which is extremely depressing. Can anybody help me figure out what?s wrong or what could be different?
I don?t know if you guys need more info or not. I built this rifle strictly for blacktail hunting in western Oregon.

[Bigs28]

Optic not mounted correctly.
Barrel nut not torqued to spec.

[Blinds]

I let a buddy borrow my vice block and never got it back and I did have a local gun shop torque my barrel this time. I mounted the optics exactly the same and have never had issues before. Optics were my first thought as well but everything seems fine in that department

[lazyengineer]

Some folks seem to think the matting of the barrel to the upper matters. In particular, lapping the face of the front of the upper, for a uniform mating/pressure to the barrel extension flange. I've been less convinced about this, but sometimes wonder if maybe they are onto something. Basically, this is the only variable you just changed, and sure enough, switching to the more budget brand upper corresponds to that proven barrel now opening up.

Could also be torque or the muzzle device since you had to reattach that with the build, but I wonder all the same. So please, keep us updated on your progress, particularly if you adjust torque on the BBL nut, muzzle device, and let us know if that changes anything.

Also, try a couple more range trips - being able to shoot a nickle sized groups isnt easy, and could have just not been your best day at the range this last time.

[A5BLASTER]

First thing I would check is if the gas tube is binding up in the bcg or the hole through the barrel nut.

If that checked out good then I would break it lose, lapp the reciver face so you have a square lock up for your bolt lugs.

I then I would check the muzzle device and it's torque setting.

Look for gas leaks around the gas tube entrance to the gas block. Around the gas block and barrel. Gas being out of balance could be effecting the groups due to the rifle working harder.

I personally would go back to the adjustable gas block myself.

If the barrel has a loose fit in the upper reciver you can bed it as well.

Hope this helps sir.

I have one of the AA 16 inch fluted light weight barrels myself. To bad they don't make them anymore those barrels can flat out shoot.

[Blinds]

Sorry if I sound dumb. But lapping the upper face to the barrel?
I have a range setup at home and do most of my shooting there. After shooting about 100 rounds on paper over a few shoots I moved to my steel targets. I have 8? by 8? steel plates out to 350yards. I could pretty much hit the plate every shot at 350 which is as far as I?m likely to harvest a deer and good enough for me. After 100 rounds on paper with this new build (none of which felt very good to me) I moved out to the plates and past 150yds I had trouble consistently hitting the plates. At 350 I could hit the plate 1 out of every 5 shots.
Just changed things around for cosmetics and now I?m extremely disappointed with the rifle after all the money and time I?ve put into it.
I?m also using a Leupold vx3i if that matters to anyone.

[A5BLASTER]

Sorry if I sound dumb. But lapping the upper face to the barrel?
I have a range setup at home and do most of my shooting there. After shooting about 100 rounds on paper over a few shoots I moved to my steel targets. I have 8? by 8? steel plates out to 350yards. I could pretty much hit the plate every shot at 350 which is as far as I?m likely to harvest a deer and good enough for me. After 100 rounds on paper with this new build (none of which felt very good to me) I moved out to the plates and past 150yds I had trouble consistently hitting the plates. At 350 I could hit the plate 1 out of every 5 shots.
Just changed things around for cosmetics and now I?m extremely disappointed with the rifle after all the money and time I?ve put into it.
I?m also using a Leupold vx3i if that matters to anyone.

Yep you can buy a tool that will remove and square up the face of the reciver so when you torque down the barrel nut the barrel extention and reciver torque down square.

It's good for the bolt lugs to lock and unlock square.

If it shoot great the way it was first built I would start reversing what I did one part at a time and shoot it before I changed back to anouther part.

That will tell you what the problem is are you will end up with what you started with and it will be shooting good again.

Old saying still stands. (If it ain't broke don't fix it)

[FLshooter]

AR15 upper receiver lapping tools run $35 on Brownells.I lap all my upper receivers before barrel installation.I have never found one to be off.But,anything is possible.

[rabiddawg]

You done flubbed up that barrel. I will give you $3.50 for it. And if a5 tries to out bid me beware. His money comes from s xerox machine.

[VASCAR2]

You changed gas blocks which can affect barrel harmonics. I suggest you make sure the gas block is not able to contact the hand guard during recoil. Did you bed the new gas block with Loctite? As others said the gas tube and/or gas block could be a little out of alignment.

[Six5x39]

This might take a while , but I guess you can eliminate it by going back to original configuration first . Then isolate it by installing 1 item at a time ? I would try that if there are no obvious signs . This way your not spending anymore hard earn money . Just need to invest some labor n range time

[Blinds]

Thanks for the info guys I?ll take use what you gave me and give you guys an update.

[Blinds]

Ok so I worked on my rifle a bit last night. I took my rail off to look things over and I noticed my gas tube touches my barrel nut just a tiny little bit. Could that be messing with my gas system?
I already put the jp back on and the gas tube doesn?t touch with that gas block. I took the jp off in the first place because the adjustment screw seized up and I can?t adjust the gas system with it. I?ll be doing some shooting on my lunch break and we will see If that changes anything.

[Mad Charlie]

AR15 upper receiver lapping tools run $35 on Brownells.I lap all my upper receivers before barrel installation.I have never found one to be off.But,anything is possible.

Three out of four of mine have been off, one quite a bit. From various manufacturers. To me, lapping and bedding is just part of the build procedure.

[Mad Charlie]

Ok so I worked on my rifle a bit last night. I took my rail off to look things over and I noticed my gas tube touches my barrel nut just a tiny little bit. Could that be messing with my gas system?
I already put the jp back on and the gas tube doesn?t touch with that gas block. I took the jp off in the first place because the adjustment screw seized up and I can?t adjust the gas system with it. I?ll be doing some shooting on my lunch break and we will see If that changes anything.

I am assuming that you have adjusted that gas block in the past, there seems to have been some confusion about which screw is which on some models of gas block. Just an idea I had when you mentioned "seized up".