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Posted: 11/8/2007 7:39:04 PM EDT
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Just put a new A1/C7 upper from JT Dist. on a Double Star lower I have been using with another upper. Now there is a gap between the upper and lower. The good thing is even with the large gap there is very little play when the upper and lower are closed. I have 4 other AR's and have never had this problem before. Not sure who the maker of this upper is, can't find a forge mark anywere on it. I just got the upper from JT Dist. and they don't show the name of the maker on the website. So I want to know will this gap hurt anything or should I get over it. It just bugs the hell out of me, since I just spent money and time getting this upper built by gun smith in another state. Thanks!!! |
since it doesn't wobble. 
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Aw, that just sucks...but if you can mix JB Weld to where it sets up good and hard, you can make the receivers fit tight. Simple stuff like modeling clay, candle wax and masking tape keep the job within reach of anyone. Get the above stuff plus a can of carb cleaner (or brake cleaner). One of those rubber inserts (Accu Wedge) can be of use here, only to tension the receivers while curing...take it out after finished. Step 1. Clean the upper. Just the flat area where it contacts the lower receiver. Clean it well with the brake/carb cleaner. Then clean again with a Q-tip soaked in the cleaner. This surface needs to be white glove clean for the JB Weld to adhere. Step 2. Apply a THIN layer of candle wax to the mating surface of the lower. Heat it with a hair dryer to thin it out, then wipe it down. Step 3. Mask and fill. Mask off all areas of the lower on the outside and magwell. Step 4. Mix and apply a THIN layer of JB Weld to the UPPER mating surfaces. Very thin, just thick enough to cover the finish, no drips. This is critical, too much is a PITA, too little and it won't fill. Step 5. Let it set up UNASSEMBLED for at least 45 minutes. Then assemble, making sure the takedown pins are free of any JB Weld. Let cure for at least 4 hours before trimming squeeze-out. Use a knife made from a scrap brass case, it will not damage hard anodized finish. Do not disassemble for at least 6 hours. Step 6. After 6 hours, disassemble the upper from lower, pushing both pins out. Pull the upper off the lower. Use the brass knife to trim any squeeze-out from the inside. Remove masking and modeling clay, clean with a good copper solvent to remove the marks from the brass knife. You should not be able to see any JB Weld unless you pull the receivers apart. It will last for years. |
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It's normal. Some the most accurate M16s I qualified with were a very, very loose fit. You dont want it too tight anyway. If you were really force recon you would know better than worrying about something like that.  If you put JB weld on that weapon you are going to make Eugene Stoner's ghost cry. It's not a fudd gun for crying out loud, it's not supposed to fit tight. |
No, I am not ex Force Recon. Just use the name in memory of a friend who was. Thanks for your help |
Seriously, if you want I will do a video clip of the loose upper/lower fit on my new Colt LE6920. A sqeaky tight fit is really someting that is new to the civilian market because in most civilian firearms, loose is bad, and consumer desires are often catered to. If you were to examine a cross section of LE and Military AR15s, M4s and M16s, you wuld find that the upper to lower fit varies from snug to downright wobbly. This is a different system entirely from a standard hunting semi or bolt gun. Put a few thousand range rounds downrange. After a while it will seem completely normal when you see it functions as it should. |
Just ribbin' ya
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Good plan. As to the "cosmetics" that everyone whines about - Christ you'd think this place was a high school girl's locker room the way people obsess over looks. Makes you wonder if they ever SHOOT thier rifles/"safe queens" (or only shoot pictures for the internet?!?!). IT'S AN F-IN RIFLE - IF IT SHOOTS, THEN QUIT COMPLAINING. You did fine on your build. Now get to the range & enjoy it as it was meant to be enjoyed (happiness is a warm gun. And a large pile of spent brass). |
Your right " More time shooting less time worring about how it looks" I was just wondering about the gap beacuse the last one I had built was a Mega upper and lower and fit was GREAT. Now I know that this normal. Thanks!! |
You must kidding. Why would anyone do this to a perfectly good AR? |
Because it is INVISIBLE and perfect. When you are shooting at targets 600 yards distant with iron sights, ANY variable means something, if only mental. |
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