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Posted: 12/13/2008 3:53:14 AM EDT
Here are a few things to improve the accuracy of your AR, some well known, some not so well known....
I bought this from a guy that said it shoots like a shotgun, the rounds scatter all over the target, here is a picture of the rifle as i got it, sans the Eotech. 
I ordered a MI freefloat to replace the UTG handuards... The Mi instructions say to cut off the Delta ring, i figured by the time i took out the dremil and used the fragile 27 cutoff pieces that it would take to cut it off, it was easier to take the barrel off instead... The first problem i noticed was that the barrel was very over torqued, (over 125ft. lbs.), and while i had it off i proceeded to do accuracy trick #1 Put the bare upper receiver on a flat surface, i use a machinist block, you can use a piece of glass, and use a quality square or a straight edge and put it against the picatinny rail, see the gap? I've had them from a slight lean to as bad as the "Leaning tower of Pisa" I found that billet ones(LaRue, Vltor) seem to be perfectly straight... This is a picture after i straightened it.... Now i will show you how i did it...Brownells sells a tool so reasonable that i bought instead of making it, my trade cost was $17, yours retail is $21... 
Here is a picture of the tool in use, you put some grinding compound on the face of the receiver or on the tool, and the long part of the tool is the guide, so it makes it foolproof, and you put the other end in a drill and you do it for 10 seconds.... 
In this picture the tool is not quite in, it goes right up to the threads... Notice in this picture the finish is only removed from the receiver at the 2 and 8 o'clock positions, thats the part that was crooked.... 
Now i reinstalled the barrel to 35lbs of torque, then the freefloat, so now i have my bolt in line with the receiver, which is in line with the barrel, which is properly torqued, and my sling won't change my POA..( military habits die hard)... 
I also while i was at it, replaced the extractor spring with a BCM 5 coil, with black insert, and a 2 stage trigger....Here is a completed picture... 
I have rail covers and ladders that have to install yet, the rifle is also a lot lighter.. Also while i shot it before i made the changes and the guy was right, it shot all over the place, i haven't been able to shoot it yet, but i have done this many times before and i always have seen an improvement.... |
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Posted: 12/13/2008 4:12:34 AM EDT
[#1]
some very cool tips.. thank you
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Posted: 12/13/2008 6:27:43 AM EDT
[#2]
That's quite interesting, and addresses something I've never checked but will be looking at.
Wow! 125 ft. #! How'd you get it off? |
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Posted: 12/13/2008 8:23:25 AM EDT
[#3]
Quoted:
That's quite interesting, and addresses something I've never checked but will be looking at. Wow! 125 ft. #! How'd you get it off? With a breaker bar and a pipe!! |
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Posted: 12/13/2008 10:01:57 AM EDT
[#4]
I've done this to all three of my builds. I don't check first, instead use the tool right off and check the pattern. Two of my receivers were off, one more so than the other. Good tip, I believe it's similar to bedding a barrel.
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Posted: 12/13/2008 10:06:52 AM EDT
[#5]
I'd like to see more pics of your tool board!
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Posted: 12/13/2008 10:13:58 AM EDT
[#6]
What is the name and catalog number of that tool from Brownells?
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Posted: 12/13/2008 10:50:04 AM EDT
[#7]
Quoted:
What is the name and catalog number of that tool from Brownells? Its Brownells stock number is 080-000-182 . Might well be worth it. |
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Posted: 12/13/2008 12:48:50 PM EDT
[#8]
Quoted:
I'd like to see more pics of your tool board! Hows this? 
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Posted: 12/13/2008 12:55:55 PM EDT
[#9]
the pics don't work. ar-jedi |
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Posted: 12/13/2008 1:11:05 PM EDT
[#10]
Quoted:
the pics don't work. ar-jedi ditto...only the second pic works. mince |
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Posted: 12/13/2008 2:15:21 PM EDT
[#11]
Quoted:
the pics don't work. ar-jedi +1 
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Posted: 12/13/2008 3:10:31 PM EDT
[#12]
Quoted: the pics don't work. They did a few hours ago when I first read this post. I sure hope the OP'er can get them fixed, 'cause this is some good info for us beginners. |
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Posted: 12/13/2008 5:49:43 PM EDT
[#13]
Still seeing nothing but XXXXXXXXXXXXXXXs...
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Posted: 12/13/2008 6:54:40 PM EDT
[#14]
much interest in this thread, but the red x syndrom isn't helping.
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Posted: 12/14/2008 1:50:19 AM EDT
[#15]
Quoted:
Quoted:
the pics don't work. They did a few hours ago when I first read this post. I sure hope the OP'er can get them fixed, 'cause this is some good info for us beginners. I'm glad this is helpful to you guys that are just starting out, it is pretty foolproof, and it will encourage you to do more....I fixed the pictures......
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Posted: 12/14/2008 3:40:03 AM EDT
[#16]
Very nice tips,.....
Thnaks for the info!
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Posted: 12/14/2008 4:09:31 AM EDT
[#17]
Great post. I'm going to get one of those tools just for general principle. Stupid question time. How does one accurately measure the amount of torque applied to the barrel nut? What tools? I'm using the DPMS multi-tool to install and remove barrels. I just snug it up, tight but not hardcore, cheater bar tight. I use the Panther Claw to work on AR's. Obviously a Panther claw won't work with the Brownell's tool. How are you securing the receiver in the vise? |
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Posted: 12/14/2008 4:35:41 AM EDT
[#18]
Quoted:
How does one accurately measure the amount of torque applied to the barrel nut? You use a Torque Wrench. |
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Posted: 12/14/2008 4:39:08 AM EDT
[#19]
Quoted:
Quoted:
How does one accurately measure the amount of torque applied to the barrel nut? You use a Torque Wrench. How is the torque wrench attached to the DMPS tool, to get an accurate measurement? |
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Posted: 12/14/2008 4:39:27 AM EDT
[#20]
Quoted:
Great post. I'm going to get one of those tools just for general principle. Stupid question time. How does one accurately measure the amount of torque applied to the barrel nut? What tools? I'm using the DPMS multi-tool to install and remove barrels. I just snug it up, tight but not hardcore, cheater bar tight. I use the Panther Claw to work on AR's. Obviously a Panther claw won't work with the Brownell's tool. How are you securing the receiver in the vise? Hi Zeke, The barrel for the AR should be torqued between 30 and 80 ft lbs, i found that less torque produces better accuracy for me, overtorqueing is especially harmfull, because you are distorting the aluminum receiver... You are right about the panther claw and others to be able to use the tool, what i do is mount it sideways in a leather jawed vise, what ever you do, don't hold it in your hand when you do it, (ask me how i know lol ) Also make sure your dustcover is open, the tool is a very precise fit...Hope this answered your questions..Tom |
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Posted: 12/14/2008 4:41:58 AM EDT
[#21]
Quoted:
Quoted:
Quoted:
How does one accurately measure the amount of torque applied to the barrel nut? You use a Torque Wrench. How is the torque wrench attached to the DMPS tool, to get an accurate measurement? I use the GI one with the square hole it it for the torquewrench... 
In the first picture you can see it hanging on the top on the pegboard.. |
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Posted: 12/14/2008 4:57:12 AM EDT
[#22]
OK. The fog is clearing up now. The DPMS tool has the same attachment point. Questions answered. I'm getting one of those first thing Monday AM Thanks for giving me a reason to buy more tools and hole up in the garage. ZM |
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Posted: 12/14/2008 7:54:27 AM EDT
[#23]
The DPMS tool has a 1/2" socket hole for use with the torque wrench, just like the GI tool does. But since the DPMS tool engages so much more of the barrel nut, I think the nut gets more even pressure and thus it's easier to properly torque.
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Posted: 12/14/2008 8:14:50 AM EDT
[#24]
Quoted:
But since the DPMS tool engages so much more of the barrel nut, I think the nut gets more even pressure and thus it's easier to properly torque. This has been my experience as well. |
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Posted: 12/14/2008 10:00:20 AM EDT
[#25]
Some excellent info:
Thanx, rjw |
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Posted: 12/14/2008 10:57:59 AM EDT
[#26]
dbl tap
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Posted: 12/14/2008 10:59:38 AM EDT
[#27]
Thanks for the info. I'm going to check my builds. Never saw that before.
The Yankee Hill free float nut does not have a hole for the torque wrench. I've been told I can use a standard AR wrench and just line the pegs up different. |
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Posted: 12/14/2008 11:55:59 AM EDT
[#28]
interesting. I have a similarly MOA-challenge rifle that I might try this on.
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Posted: 12/14/2008 4:18:59 PM EDT
[#29]
Quoted:
The DPMS tool has a 1/2" socket hole for use with the torque wrench, just like the GI tool does. But since the DPMS tool engages so much more of the barrel nut, I think the nut gets more even pressure and thus it's easier to properly torque. Just make sure to use the torque wrench perpendicular (at right angle) to the barrel nut tool, otherwise the extra length of the tool will add additional torque above what the wrench is set to. I usually set the wrench to minimum torque, tighten, then align to the next gas tube hole. |
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Posted: 12/14/2008 4:39:46 PM EDT
[#30]
Quoted:
Just make sure to use the torque wrench perpendicular (at right angle) to the barrel nut tool, otherwise the extra length of the tool will add additional torque above what the wrench is set to. Not true. The torque range takes into account for the length of the wrench. The -23 calls this out. 
Colt factory barrel installation. 
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Posted: 12/14/2008 4:55:23 PM EDT
[#31]
Quoted:
Quoted:
Just make sure to use the torque wrench perpendicular (at right angle) to the barrel nut tool, otherwise the extra length of the tool will add additional torque above what the wrench is set to. Not true. The torque range takes into account for the length of the wrench. The -23 calls this out. http://img.photobucket.com/albums/v489/Metroliner/twrench.jpg Colt factory barrel installation. http://img.photobucket.com/albums/v489/Metroliner/torquewrench2.jpg Interesting, the -23 does state that. It also states do not torque past 80 ftlbs. So I assume that is also in combination with the barrel wrench, which would make the actual max more. Hmmm....learn something new every day 
ETA: I was reading the -23 while you were editing your post 
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Posted: 12/14/2008 5:01:14 PM EDT
[#32]
We had a lengthy discussion over this about a year or so ago.
Another thing regarding torque with the barrel wrench straight out from the torque wrench; If you use a torque conversion formula to figure out the added length of the torque wrench with the GI barrel nut wrench attached, you’ll find the added torque is very minimal. ETA: http://www.cncexpo.com/TorqueAdapter.aspx You can see the torque difference using the above calculator. Distance “E” is 2 for the GI wrench, and 1.5 for the DPMS wrench. I always wondered why the -23 called out for the wrench to be attached as it does. This does infact increase the length of the torque wrench arm which in fact increases the torque. But, it’s there in black and white. Also, if the barrel nut torque was THAT critical, why not just rotate the adapter 90 degrees like you stated, or use the calculation as outlined in the link above. |
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Posted: 12/14/2008 5:38:46 PM EDT
[#33]
I agree that it isn't that critical. If it was, they would include the spec for lubed threads or not, which is usually 15%.
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Posted: 12/14/2008 5:50:53 PM EDT
[#34]
Another note on the barrel torque.
If you follow the steps as outlined in the -23, they first have you torque the barrel nut at 30 ft-lbs, stating the barrel wrench and torque wrench are used together. Now using the GI barrel nut wrench, and the torque wrench calculator, this would give us a difference of 3.7 ft/lbs. So in actuality, your initial barrel nut setting, if the torque wrench is set to 30 ft-lbs, would be 33.7 ft-lbs. Continuing on with the -23, they have you go through the 3X torque procedure to ensure the barrel nut is seated correctly on the upper receiver. You then back off the barrel nut, and with the torque wrench still set at 30 ft-lbs, you torque the barrel nut. Now it does warn you not to exceed 80 ft-lbs final torque, but states that the barrel nut can be torqued beyond the 30 ft-lb to align the barrel nut serrations. My experience with barrel nut installation has been that the 3X torque procedure is the key to barrel nut alignment. Most often it takes more than three applications of torque to get the barrel nut serrations to line up. But, with each subsequent torquing, the serrations get closer and closer to alignment. When this procedure is followed, I find it hard to see going over the 80 ft-lb max. |
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Posted: 12/14/2008 5:52:16 PM EDT
[#35]
Quoted:
I agree that it isn't that critical. If it was, they would include the spec for lubed threads or not, which is usually 15%. Another good point. Wet torque is always more than dry torque. |
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Posted: 12/14/2008 9:48:50 PM EDT
[#36]
Quoted:
Quoted:
I agree that it isn't that critical. If it was, they would include the spec for lubed threads or not, which is usually 15%. Another good point. Wet torque is always more than dry torque. Why does it sound so dirty when YOU say it?? |
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Posted: 12/25/2008 7:24:37 AM EDT
[#37]
What grit abrasive did you use with the upper receiver lapping tool? I see Brownell's recommends 180 grit but that seems a bit coarse. Just curious.
Cheers, cc |
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Posted: 12/25/2008 10:15:01 AM EDT
[#38]
I use 800 grit valve grinding compound, unless there is quite abit of correction needed then I'd use something coarse. Most aren't off by much if any.
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Posted: 12/25/2008 10:15:46 AM EDT
[#39]
Oops!
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Posted: 12/25/2008 10:45:17 AM EDT
[#40]
I use valve grinding compound, a left over from my powerplant mechanic days. I do not know the grit.
Truing/squaring the receiver is an excellent tweak to making the AR just that much more accurate. |
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Posted: 12/25/2008 11:22:54 AM EDT
[#41]
What is the OD of the lapping tool where it goes inside the reciever? 1.000"? 0.995"?
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Posted: 12/25/2008 2:32:10 PM EDT
[#42]
Interesting. Good informational post
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Posted: 12/26/2008 2:58:34 AM EDT
[#43]
Quoted:
What is the OD of the lapping tool where it goes inside the reciever? 1.000"? 0.995"? 1.000......... |
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Posted: 12/27/2008 9:42:06 PM EDT
[#44]
Do you know of anybody who makes one of these tools for the AR10/DPMS size receivors?
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Posted: 12/28/2008 3:04:55 AM EDT
[#45]
Quoted:
Do you know of anybody who makes one of these tools for the AR10/DPMS size receivors? I don't know of any offhand, if you know a machinist, it would be fairly simple to make... |
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Posted: 12/28/2008 4:08:09 AM EDT
[#46]
My son just go back from Iraq. As a thank you for his service I'm building him a new AR based on Mega receivers.
Having seen this post I immediately pulled out the upper and did a check.....it seemed to be perfect. Never-the-less Im buying that tool. The Desert Tan receivers are the ones that's being built out. In the photo they look kinda pink however, they are quite "Desert Tan".....should be done about the first of the year. 
Nevadasun PS. Excellent Post |
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Posted: 12/28/2008 6:00:10 AM EDT
[#47]
Very good tips.
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Posted: 1/2/2009 3:57:08 AM EDT
[#48]
Very good post!
Weaponizer, when truing up the front for 10 seconds, do you let the tools pressure do the work or is there a certain amount of pressure you put on the drill? |
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Posted: 1/2/2009 5:22:52 AM EDT
[#49]
125 ft/lbs?
Could this be the cause of the guns accuracy problems? Im new to building AR's but was told high barrel torque will ruin accuracy. To see if that tool makes any difference you would have to 1. Shoot the gun with the barrel at 125ft/lbs to get a base line. 2. Retorque the barrel correctly at 30ft/lbs and test shoot it. 3. Then again after truing the back of the receiver with the barrel at close to 30ft/lbs. Compare results. |
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Posted: 1/2/2009 8:16:33 AM EDT
[#50]
Quoted:
Very good post! Weaponizer, when truing up the front for 10 seconds, do you let the tools pressure do the work or is there a certain amount of pressure you put on the drill? Not Weaponizer here but, the pressure required is determined by how much contact your initial cut is making. Also know that the more pressure you use, it is more likely to get things to go awry. Let the lapping compound do most of the work and don't let the tool stay on contact but afew seconds at a time (lifting and reapplying with drill motor running). They say to look for contact of 80% or better. I go for 100%. |
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