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Posted: 3/31/2007 1:30:25 PM EDT
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Gents, I found a M-16 upper without the forward assist and a bird cage flash suppressor but no bolt . It looks to be in excellent condition and I was thinking it would be great for a retro build. The hole in the lug that hooks it to the lower receiver appears to be larger than the ones found on the lower receivers. What pin do I get to hook the large hole upper to the small hole lower, or is there such a beast? Can I get a new bolt to use in the upper, or is this dangerous? How do I check the head space? I remember in basic the DIs told us not to get our bolts mixed up when we were cleaning our rifles. What is a fair price to pay? Thanks for any help. G57 |
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Offset Bushing Any new bolt will work. To check the headspace you will need a "Field" headspace gauge. Your upper sounds like a Colt SP1 upper. |
| What you found is a Colt SP1 upper, the M-16 uppers have the small hole. They make a bushing for the large hole so it can be used with small hole lowers. You need gauges to check headspace, but a new bolt should be fine. $250-300 is a good ballpark. There are plenty of A1 barreled uppers in the $200-250 range these days and they have the correct size hole. M16 uppers can be found as well. |
+1. Note that when you get the bushing the hole is a bit offset. That's to allow you to set the thing so that the upper will lie evenly along the lower. Start with the thin edge of the bushing straight up, and make any slight adjustments forward or back, so that the upper lies straight accross the top of the lower. If your bushing is a snug fit in the upper hole, you can coat the outside with high strength Loctite and make the fit permanent. The unit I got was a bit to loose in the upper I had for Loctite to work, so I used a putty type epoxy around the outside. Two years and about 800 rounds later, the adapter is still fine 
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