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Posted: 5/13/2008 11:14:20 AM EDT
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Here is a quick write-up the Mission Specific Barrel Quick Change System (MSB) from M&A Parts. I had a familiar problem with too many matching lowers to every upper receiver I owned. I decided to look at using a single upper/lower combination and to change out the barrels depending on what my need was going to be for the day. I look at a number of systems, which included the MGI setup, but at $600, it proved to be too cost prohibitive. I ended up ordering the Quick Barrel Change Kit offered by M&A Parts, Inc. The kit itself was simple. It consisted of a replacement barrel sleeve, two barrel nuts, a barrel nut wrench and complete instructions.  The kit comes ready for being able to swap out two barrels to the same upper with additional barrel nuts available for any additional barrels you may have. My target for this build was a 16” M4 carbine on a Mega upper that I wanted to swap out with a 20” 1:8 SS for target shooting I also obtained from M&A. Now to setting up the upper receiver. The replacement sleeve screws onto the upper. Here is a shot minus the weld spring, delta ring and c-clip.  I removed the nut and proceeded to assemble with the delta ring, weld spring and c-clip.  Tip: Try to get the spring and c-clip lined up together somewhat close BEFORE screwing the assembly onto the upper. It makes things a lot easier that trying to chase them around once everything is mounting to the upper.  Now time to attack the barrels. You need to remove the FSB in order to remove the original barrel nut and to slip on the replacement nut that secures the barrel into the newly sleeved upper. Install the nut so that the cutouts for the castle nut are towards the end of the barrel. Now re-read this and check the nut before you get the FSB pinned back on, you’ll thank me. Here is the completed assembly:  This was the really fun part. Take the barrel assembly and slide it into the sleeve on the upper:  Snug up the nut (snug. not torqued) with the supplied wrench, snap on the hand guards and you’re ready to go. The barrel nut is designed to securely hold the barrel with a minimal amount of torque.   The system works fantastic. I can now go from a 7” SBR to a 20” target barrel and back to a 16” carbine in less than a minute per change. After 600 rounds, I found the barrel nut to be as secure and as easily removable as when I first installed it. Here is a quick movie I put together to show a barrel change - VIDEO |
I swapped them out a half a dozen times already and I have not had to re-zero. The iron sights still worked out to 200 yards. I was using a Leupold Mk4 on a 20" barrel and it was still right on. That was an excellent question though. I should have included that in the write-up. Thanks. |
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