Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

4" groups not acceptable!!' Help Please


j.peace

Recommended Posts

I recently assembled my first lr-308.

I have assembled a few ar's with no issues all three ran around 1 to 1 1/2 groups at 100 yds.On Bipods. Not the case with my 308.

Before ordering parts I knew accuracy is a must so I sprung for the mega 18" guaranteed sub 1 moa at 100.

Before I got my scope in I sighted in with mbus sights. 4" groups was my best. I thought it was me and I needed a scope.

So I put a brand new redfield battlezone. 3 x 9 x 42 and for a base I used a nikkon m-223 1 piece mount.

The scope has bdc for 168 gr. Bullet.

I ran PMC 145 gr. And winchester 150 gr. Both with same results. I also ran a bore snake through a few times between mags.

It seemed the first couple were very tight after allowing to cool. Then as it got hotter the poi would shift.

I really don't think its the scope because same results were seen with open sights at 50 yds.

I also triple checked scope mount bolts for torque .

It is possible that my barrel nut may be a little loose the holes aligned up at 30 lbs of torque even after loosening and tightening it several times.

But my free float rail won't move by twisting it by hand.

And there is some play between upper and lower.

Tomorrow I will remove rail and gas tube and recheck barrel nut torque (several times I'm sure), and I have an extra wedge so I'll put that in.

And I will also try and run down some heavier bullets pref. 168 gr.and I will try it again at 100 yds.

And I known it ain't me cause I had no problems performing with the ar today. I was shooting a mag. Of 308 then a mag of .223 rotating back and forth between weapons on different targets. 223 2" groups all day long.

.308 4" the best prolly closer to 6"

Again it seems the poi is moving. A coople or three will be close then poi shifts.

Please help. This is my first .308 and I'm very proud of it and I know its capable of performing better.

Any ideas or help is very appreciated

You guys have helped me make sure I ordered the right parts. Please help again and let's make this thing a heyholer!!

Edited by j.peace
Link to comment
Share on other sites

  • Replies 50
  • Created
  • Last Reply

Top Posters In This Topic

Something in the upper is moving - barrel nut definitely check.  That barrel, or the optics, are moving on you. 

 

How your shooting technique?  I can't imagine it's bad, because the .223 is putting down 2" groups at the same distance.

Link to comment
Share on other sites

Hey J at 100 you ought to have just one big ol hole....get yourself some privi match 168 and get the barrel nut tight..even 80 lbs on the torque wrench is fine...most of mine line up bout 60 or so   I was at the range Friday shooting two of my rainier 16" barrels out to 500 using a nikon 308 bdc on one and a monach ed with custom turret for 168 on the other......fired 60 rounds out of the nikon 308 and never missed a swinger

it aint the barrel...well im fairly sure....and your scope might be a problemo too   :)  Wash

Link to comment
Share on other sites

I agree with all of the above. Barrel nut first. I had one that I had to get extra tight in order to get the accuracy that was expected. Also check that your muzzle device is secure. Also check the muzzle for any nicks at the exit.

 

I am familiar with the handguard that you have. I had one that I could never get tight enough. By hand, it may feel tight, but under the recoil it can move slightly, which is enough to throw off your shots. Clamp it in the vice (protect the finish) and wiggle your stock latterally to check tightness.

 

Of course, throw some 168 or 175 match ammo through it as previously mentioned. However even will ball ammo, you should be getting significantly less than 4 MOA.

Edited by Owl21
Link to comment
Share on other sites

J I wouldnt be clamping my rifle in a vice and trying to wiggle the forend.....not a real sound idea.

use a torque wrench to tighten the barrel nut....and then leave it alone put the handguard back per mfg instructions :) Wash

go get a 5/8x1/2x1/16 o ring at hardware store and place it on the front post //takedown of your upper....that will snug it up....dont need no stinkin accu wedge

Edited by washguy
Link to comment
Share on other sites

J I wouldnt be clamping my rifle in a vice and trying to wiggle the forend.....not a real sound idea.

use a torque wrench to tighten the barrel nut....and then leave it alone put the handguard back per mfg instructions :) Wash

 

 

Oh yeah? Why is that? Would a rifle take more or less abuse in actual combat? You know, clanging in and out of vehicles, being pounded on the ground while sprinting to new positions, etc., etc. Regardless of whether this rifle is a safe queen, bench rest paper shooter, or something less than its intended purpose, it is still a battle rifle. And a battle rifle should be able to withstand abuse.

 

My suggestion is not in any way abusive (if properly performed) and is based on experience with his particular handguard and the fact that installing it per the manufacturer's directions may not be sufficient, and testing by hand can be inconclusive. And simply saying "I installed it per the manufacturer's directions" does not actually indicate that it is working as intended; you know, kind of like installing a barrel nut to 30 ft lbs, per the manufacturer's instructions, not necessarily being enough in some circumstances.

Link to comment
Share on other sites

Oh yeah? Why is that? Would a rifle take more or less abuse in actual combat? You know, clanging in and out of vehicles, being pounded on the ground while sprinting to new positions, etc., etc. Regardless of whether this rifle is a safe queen, bench rest paper shooter, or something less than its intended purpose, it is still a battle rifle. And a battle rifle should be able to withstand abuse.

My suggestion is not in any way abusive (if properly performed) and is based on experience with his particular handguard and the fact that installing it per the manufacturer's directions may not be sufficient, and testing by hand can be inconclusive. And simply saying "I installed it per the manufacturer's directions" does not actually indicate that it is working as intended; you know, kind of like installing a barrel nut to 30 ft lbs, per the manufacturer's instructions, not necessarily being enough in some circumstances.

Just ignore him and do whatever you wish to it, and then take that piece of equipment you're staking your life on into battle. Your family can sue Armalite for not designing a vice-friendly upper receiver...

Link to comment
Share on other sites

Just ignore him and do whatever you wish to it, and then take that piece of equipment you're staking your life on into battle. Your family can sue Armalite for not designing a vice-friendly upper receiver...

 

WTF? They make vice blocks specifically for putting your upper (or lower for that matter) receiver into a vice. AR manufacturer's use them hundreds of times per day.

Link to comment
Share on other sites

So here's the update:

This morning first thing I did was strip it down to the upper,barrel but and barrel. I loosened up barrel nut rhen tightened. Then repeated a couple of times. 80 lbs. Was between holes so I backed it off till holes ligned up.after tightening barrel nut I could tell it was one hole tighter tan originally. Reassembled upper and put the wedge in.

Washguy can you post a picture of your o-ring. It sounds like a great idea.

So I couldn't track down any 168 gr. But I found some 165 gr.

After hitting the range.I decided to shoot some 150 gr. And 145 gr. First.

150 gr. Was hitting. 2 moa. 145 gr. 3 moa. And I'm sure you could give me some room for error as I was shooting off bipods.

And blue. I left bipod legs collapsed all the way in. After looking at them I thought it may be possible legs could push back in under pressure.

Link to comment
Share on other sites

Here's a picture of target shooting 165 gr. Fusion. Looks like hunting ammo.

Bottom two holes I was still adjusting scope. I think it was mostly the loose barrel nut causing the poi to shift. And I know my Mega 18" barrel likes the heavy rounds.

I'm Very impressed myself.

Baby's not sick no more. Thanx 308.com forum members. You guys are great!!!

post-14859-0-26279300-1405968974_thumb.j

Link to comment
Share on other sites

WTF? They make vice blocks specifically for putting your upper (or lower for that matter) receiver into a vice. AR manufacturer's use them hundreds of times per day.

The man gave you good advice and you balked at it, I'm just suggesting that if you don't intend to heed good advice go on and do whatever you like. People who ignore good advice are inadvertently good for the economy, so go for it.

Link to comment
Share on other sites

The man gave you good advice and you balked at it, I'm just suggesting that if you don't intend to heed good advice go on and do whatever you like. People who ignore good advice are inadvertently good for the economy, so go for it.

 

What? Who gave me advice on what? I was not seeking advice, nor did I note anyone giving advice to me; though my advice to the OP was disputed by someone else.

Edited by Owl21
Link to comment
Share on other sites

I agree with all of the above. Barrel nut first. I had one that I had to get extra tight in order to get the accuracy that was expected. Also check that your muzzle device is secure. Also check the muzzle for any nicks at the exit.

 

I am familiar with the handguard that you have. I had one that I could never get tight enough. By hand, it may feel tight, but under the recoil it can move slightly, which is enough to throw off your shots. Clamp it in the vice (protect the finish) and wiggle your stock latterally to check tightness.

 

Of course, throw some 168 or 175 match ammo through it as previously mentioned. However even will ball ammo, you should be getting significantly less than 4 MOA.

 You never mentioned about using a barrel vice , receiver block or an upper receiver clamp , the advice was for your advice , the way I see it . The correct device to properly clamp rifle or its components is the proper way to maintain the Finnish & integrity of components .

 

  You did mention them in a later post though I see , but the reposes were before that.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...