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Posted: 6/9/2017 7:48:20 PM EDT
| I'm going to put together an upper for the first time. I have got everything I need, except for a torque wrench. Some people tell me I need one, and others don't... I heard good things about the Harbor Freight 1/2" Torque Wrench for 20$... Since the tolerences on the the AR according to torque specifications are pretty large, I don't really need an expensive torque wrench. Keep in mind, I don't need a torque wrench for anything except for putting barrel nuts on. How well will the Harbor Freight wrench do, or should I muscle up and pay for a real torque wrench, or do I need one at all? |
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It's a pretty big range, and if you're using a standard barrel nut, you're not tightening to a value. You're tightening to a minimum then advancing till the teeth align with the gas tube.
I'll not tell you it is a bad idea, particularly if you're new to building uppers. Neither will I tell you that you absolutely need one, or need some mondo quality wrench to hit such a wide window. |
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I'm going to put together an upper for the first time. I have got everything I need, except for a torque wrench. Some people tell me I need one, and others don't... I heard good things about the Harbor Freight 1/2" Torque Wrench for 20$... Since the tolerences on the the AR according to torque specifications are pretty large, I don't really need an expensive torque wrench. Keep in mind, I don't need a torque wrench for anything except for putting barrel nuts on. How well will the Harbor Freight wrench do, or should I muscle up and pay for a real torque wrench, or do I need one at all? I've put 3 uppers together with it. |
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I work on my cars a lot so buying a tool can be justified due to the other uses I'll have for it.
Do you need a TW to build an AR? No. I like to use one because I like to know it is within specs beyond a shadow of a doubt. I had one that would not line up and had I not been using a TW I would not have known I had hit the max Ft/lbs. A couple of barrel shims later and it was well within specs. 
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| Another vote for the HF wrench. If you're worried about the accuracy you can check it by mounting the drive in a vise and hang a weight from the handle. I've had mine for several years and when I checked recently it's only 2 - 3 ft lbs off when set at 45. You can also of course use it for a lot of other things, in particular torquing nuts on aluminum wheels. I believe I paid $12 about 10 years ago. They are currently $10 on the website. |
| You should be gtg with hf. I was going to buy a hf one for the same reason as you, but i ended up getting a craftsman for cristmas from my morher in law before building my upper. I don't work on torque sensitive stuff much and am usually of the tight is tight, too tight is broke school of torque. I did want to be specific with my rifle though. |
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I have built uppers with torque wrench free barrel nuts (ALG EMR) and those with a specific value.
When I need a torque wrench that I don't have, my alternative I like is to actually measure out the distance x weight and hang it at exactly 90 degrees from the nut. Example: Weight a bag of stuff at exactly 45 lbs. Place bag on the end of wrench handle exactly 12 inches from pivot point. 45 lbs x 1 ft = 45 foot pounds. If you have a 9 inch long arm, then just add more weight. 60 lbs x .75 ft = 45 foot pounds. It's just a thought, but for something with as wide of tolerances as AR barrel nuts, it gets the job done. |
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What's the best size to buy? 1/2"? 3/8"? The 1/4" drive torque wrench is most often calibrated in in/lbs and metric equivalent, the 3/8" torque wrench is generally in ft/lbs nd metric equivalent, as is the 1/2" drive torque wrench. For firearms, the 1/4" torque wrench would be useful for tightening scope rings and so forth. The others for higher torque applications. One thing I have found useful is to de-grease the numbers and lines on the handle and scales, and then rub some paint onto the numbers and lines. Makes things a lot more visible. Use different colors for inch and metric scales, to lessen chance of confusion. Here's how you can calibrate them at home for cheap: Calibrate Torque Wrench |
| Harbor freight 3/8" torque wrench is fine for what we do. I always recommend having one. They go through the trouble of giving you torque specifications for a reason and if you also get the 1/4" one in in/lb it can be used for clamp on gas blocks and scope rings. You run the risk of damaging a scope if you over tighten the rings. |
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just don't forget to have your torque wrench angled at 90 degrees to the actual wrench for accurate torquing  Here is A Link with info and formulas for unusual situations. Another point to mention is that there is Wet Torque, as when there is some sort of lubricant on the threaded fasteners, and Dry Torque, as when the fasteners are completely clean. In almost all instances, torque figures supplied are for dry fasteners. Oil under the head of the fastener, or the surface which mates to the head of the fastener has a very great "wet torque" effect; more so than oil on the threads of the fastener(s). Here's a Torque Chart giving wet and dry torque values for common fasteners. There is a great deal of disagreement/discussion about whether Loctite changes things from dry torque to wet torque. I have read presumably informed posters suggesting anywhere from zero to 20% reduction of torque applied to LocTited fasteners. Your call. |
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considering how wide the torque spec range is, you almost don't even need a torque wrench. It's a really nice thing to have though. I don't think I have ever used a torque wrench on the AR barrel nut. |
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If you mean the barrel retention nut, I agree. I have always used a proper wrench to tighten (the captive action) barrel nut to a significant level, and then moved the barrel nut so as to completely clear the gas tube. The minimum torque specs allow this to be easily within the capability of all but the most feeble. I don't think I have ever used a torque wrench on the AR barrel nut.  .
I only bust out a torque wrench for precision builds. Everything else is done by "feel" now. |
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