mark75101
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Posts posted by mark75101
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Kept me entertained.
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I'll pull the handguard/increase torque.
Might order a new stripped upper too.
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Is there a way to post pics from my iPhone?
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Seemed pretty tightHow was the fit of the barrel extension in the upper? I've seen some billet uppers that were disgustingly oversize in the bore. That can not have a good impact on accuracy.
That's a subjective term. Did it need a rubber mallet to fit, did the muzzle wobble back and forth prior to the nut being tightened?
Yes I guess it is subjective. It did not seem loose but it slide right in. No mallet needed.
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Ok. So, the lower has no effect on accuracy. You say that you have shot better groups with the ammo you have tried in the RRA upper, so this should indicate that your ammo is a known component. You have tried more then one shooter and scope, so this is all quite good in getting down to the heart of the issue. There is the possibility that you have some kind of gas tube binding or misalignment going on. This would likely contribute to SOME of the issue. I would however check and make sure that your gas block has plenty of clearance inside of your hand guard. I would also check and see how easy it is to move the barrel inside the hand guard and in general make sure everything is tight. If there is gross movement, you would see and or feel it. I highly doubt that the barrel is the issue, especially if you are on your second one.
I suspect that something is not right with hand guard installation or your upper is out of spec.
You are not bridging the upper and rail with your scope / mount are you? the scope(s) should only be on the receiver.
Knock on wood I have not had an issue with an AR build to date.
Pictures please...
No bridging.
Scope mount for the leopold is not great lol but seems to work. Its the set up I use whenever I get a new rifle just for checking loads. The Acog has a LaRue mount and the Vortex has a ADM mount.
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Are you shooting factory ammo or reloads? What kind of pattern are you seeing at 100 yards? Random or stringing of shots?
Is there a chance the gas key is rubbing the gas tube?
Have you tried shooting the gun without the compensator installed?
When installing the barrel nut, did you torque and release, then repeat, and then torque a final time to align the gas tube? Are you comfortable torquing the barrel nut a bit more? If I remember correctly, MarkCO in another thread indicated he went as high as 80 ft-lbs on some uppers.
Is the gas block fixed in place with a set screw? If so, did you dimple the barrel for the set screw?
When you installed the gas block did you leave a slight gap between the barrel and the rear end of the block? (I position a credit card between the two before I tighten the gas block.)
These were all the things I covered when I had problems with a barrel last fall. Turned out its just a mediocre barrel.
Bill
1. Both factory and reload. Random groups at 100
2. Slight rubbing on the gas tube with the fail zero bolt. The RRA seems smooth as silk, its a old BCG with alot of rounds through it though.
3. Yes. No change.
4. Torque, release, no repeat. Maybe thats it? The first barrel I torqued to 40, after seeing bad accuracy I pulled the forend and torqued to 45, no change. Haven't tried re-torqueing the second barrel though. If you think it might help I'd have no problem torqueing to a higher ft/lb.
5. Yes, 3 set screws. The barrel came with one dimple which did line up. I did not dimple the other two, just tightened till it hit the barrel and called it good for now.
6. Yes, probably not credit card thickness though. Just a slight gap because thats where it ended up with the factory dimple for set screw.
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How was the fit of the barrel extension in the upper? I've seen some billet uppers that were disgustingly oversize in the bore. That can not have a good impact on accuracy.
Seemed pretty tight
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About a month ago I put together another upper using a Rainier Arms Select 16" 1/8 mid length. I've tried 52, 55, 62, 68 and 69 grain ammo and it seems to shoot about 3 1/2"-4" at 100 yards. I tried 3 scopes and two shooters, got frustrated and sent the barrel back for replacement. The replacement is just as bad. I can put my 16" RRA upper on the lower and at least cut the group size in half.
Is there something I missed in the assembly? I really don't want to believe its the barrel.
The only thing I can think of at this point is the upper itself. Its a flat top thats been in my safe so long I don't remember where I got it. Can the upper reciever itself make a difference?
The rest of the specs:
Giesselle Mk 4 rail, barrel nut torqued to 40 ft/lbs as per instructions.
MI low pro gas block (3 set screws)
A2 flash hider, althought I did try it without a flash hider just to take it out of the equation.
Tried two lowers, RRA with 2 stage NM trigger and Spikes with Fail Zero trigger.
Leopold 12X with fine target dor
TA31RCOM4 acog
2.5X10 Vortex.
Any ideas?
Thanks
Mark
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Yes, I was just discussing this the other day. Running several business' is stressful, with travel and making sure everything is just so. I find that when I go to the range, or when I'm hand-loading 500 .45's, I don't think of anything else. I'm not cognizant of the clock or anyone around me. I seriously believe it's more than a 20 point drop for me. I'm in the NE now on a trip and missing the range....
I don't get that from hand loading, wish I did....I'd probably load alot more
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The good thing about the .223 shell plate is that it will work for 9x23. It won't work for .38 super, though.
Liota
Cool, I've been looking for an excuse to buy one
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IIRC .223 is a different plate, 9mm will work for .40 though.
Thanks, I guess I'll need the 223 powder funnel anyway.
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Will the 9mm shellplate work for 223? Or do I need both?
Thanks
Mark
bad accuracy with new AR 15 barrel
in Rifle - Technical
Posted
Got a break in the weather and went back out.
Tried increasing torque, shooting without the rail/ shooting without the gas block and tried the barrel on another upper receiver. No change.
Also tried three more loads: Hornady super match 75 gr, a 77 gr handload a buddy had and a 60 grain sierra loaded with data 68. The 75 gr group was about 3 1/2" at 100, the 77 gr was 1 1/4" the 60 was just under 1 1/2".