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Posted: 6/26/2010 5:51:28 PM EDT
| I recently finished my first AR...the barrel is a yhm 16" hbar and I have a rifle length free float diamond yhm forearm with the yhm endcap..I installed the barrel nut and forearm per YHM instructions, everything lined up with the upper reciever perfectly...I installed the endcap...I noticed the barrel is off center coming through the endcap....is the forearm bent? it doesn't appear to be...the feedramps in the barrel and the upper receiver align perfectly...the rails are aligned...is this a cosmetic issue or is the barrel crooked?...or am I missing something? |
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I'm quite sure someone with more experience will chime in...but:
1. Pictures 2. How far out of alignment is the bbl/forend cap? 3. Could the front of the receiver (the surface that the bbl shoulder mates to) be out of true and needs to be lapped? 4. How did it shoot before the YHM install? Any one else have a thought? Bruce |
| little update...thanks for the replies, I still have not torn the upper down had a little incident of small dog attacks...my boston terrorist nipped a ladies golden retriever (sun am), said lady then reported to animal control that the dog bit her and showed the animal control officer a 1/4" long scratch on her ankle that broke the top layer of skin but didn't draw blood...long story short...dog in quarantine...me breaking lease to leave apartment after being told dogs have to leave, fast forward 3 days, house located offer made...shock training collar purchased....expensive lesson (they usually are) learned |
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Forget the shock collar for what you are trying to teach the dog.
Use the reward/fear of death treatment instead. When you command it to sit, it better do such no matter what, even if eating or mid stoke of humping. Also down and stay means just that, and it does not stand back up until released from that command. You train a dog with a shock collar and it knows when the collar is not around it neck, it not going to get zapped. Also, if the dog has any speed to it, will get out of range really quick to prevent from being zapped as well. On the other hand, if the dog knows that you are alpha male, and does not respond to your commands, it's going to get a beating hard enough to met God personally really quick. Trust me, I have had Rottweilers and Dobermans, and if you can not get then trained to such levels, it's either time to find them a new owner that can, or put them down. |
| I have a boston terrier, he is completely lethal to small animals, birds and will nip bigger dogs that try and get in his business...he does not bite, attack, growl or show any aggression towards people whatsoever...in fact if I so much talk to him in a loud voice he flops over on his back in fear...the fear of imminent death thing is how I trained my both my dogs but it hasn't worked for leash training...believe me I have tried... |
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She has a large friendly dog that is like a lab (read loves to lick everyone to death and sees nothing as a threat), while you have a pocket dog that loves to chase squirrels, and when the larger dog rushed your dog, he thought that the shoe was on the other foot, with him being squirrel.
No harm, not foul and instead of getting in between the two, she should have just given her dog a tub on his leash to back him away to begin with. You can train your dog to do about anything if push comes to shove, but it will not over ride self-preservation(fight or flight), and the fact that your dog did not draw blood from here when she went to handle it the wrong way, tells me that she was not the dog intended target for the aggression. About the only thing I can add, is see if you can find a few friends with larger dogs that you can bond your dog to so he gets over the fear of larger dog around him if you have not done such already. This will calm him down on normal encounters when it comes to other large dogs so he is not so stand-off'ish from the start with flight or flight kicking in even before the normal ass sniffing that all dogs love to do as a greeting. |
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finally got the upper disassembled, the barrel and reciever appear to be correctly attached together...there is a lot of "thread slop" with the forearm...when screwed onto the barrel nut even all the way, I can loosen off the nut that holds the forearm in place and the forearm wobbles in and out of "true" is this normal?
When everything is assembleyed: -the barrel is about 2mm off center in the endcap -if I loosen the nut that holds the forearm in place the foream will wobble in and out of true but when it is tightened down it pushes the forend and makes it crooked -the feed ramps in the upper and barrel align perfectly and the barrel is extremely tight in the upper |
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Quoted:
finally got the upper disassembled, the barrel and reciever appear to be correctly attached together...there is a lot of "thread slop" with the forearm...when screwed onto the barrel nut even all the way, I can loosen off the nut that holds the forearm in place and the forearm wobbles in and out of "true" is this normal? When everything is assembleyed: -the barrel is about 2mm off center in the endcap -if I loosen the nut that holds the forearm in place the foream will wobble in and out of true but when it is tightened down it pushes the forend and makes it crooked -the feed ramps in the upper and barrel align perfectly and the barrel is extremely tight in the upper Sounds like either the barrel nut or tube was either off axis threaded, and the end of the tube no square to the threads. Give the manufacture a call to discuss a solution to the problems since it does sound like something is out of square.. |
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The problem is most likely the front of the threads on the upper receiver are not squared to the action. Most are not, not even on the $235 billet uppers. I have dozens of ARs and I have yet to find an upper of any make that does not benefit from lapping the front of the threads. What that does is square the front of the threads so the barrel extension butts up nice and square and your barrel is not pointing off in some goofy direction.
I just did an upper on a Rock River and it is the worst I have ever encountered. The rear sight was all the way to the right and still three inches out of zero at 50 yards. I had not lapped the front before because the lapping bar would not enter the upper receiver's bolt carrier raceway. The lapping bar did not want to go into the upper so I had no choice but to lap the bolt carrier raceway just to get the lapping bar in. Once the raceway allowed the lapping bar to enter, the front of the threads required a solid 10 minutes of lapping with 325 grit lapping compound to get it squared up. I normally use 600 grit and it takes only a two or three minutes to true them up. Once done though, the rifle was zeroed with the rear sight just three clicks off center. When you encounter a rifle that will not zero and the front sight is not canted, or a barrel that is not centered in the forend, it most usually will be the front of the threads on the upper are not perpendicular and squared to the axis of the bore. The Brownells/Midway AR lapping tool will square things up and get that barrel pointing in the direction it is supposed to be pointing. There are several threads here about lapping the front of the AR upper receiver so if the search engine is working it should turn them up. http://www.brownells.com/.aspx/pid=20220/Product/AR_15_M16_UPPER_RECEIVER_LAPPING_TOOL |
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Not a fan of the lapping tools since it just easier to lathe the receiver up and take a quick cut if needed off the face of the barrel extension socket to square it to the upper receiver center line.
But if you don't have a lathe, then the lapping tool would work if that is the problem at hand (read has seen some uppers that even the barrel socket has not been milled square as well). If you do plan on going with the lapping tool and is going to be a one time thing, then post in your home town forum to see if anyone around you has one (or a lathe) that can give you a hand. |
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