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1/25/2018 7:38:29 AM
Posted: 10/20/2003 10:49:47 AM EST
Hello. I need some help. I have a Bushmaster upper receiver that has a BMAS Carbine forearm (actually it is made by Yankee Hill Machine company secure.valinet.com/~yankeeh/cgi-bin/web_store/web_store.cgi?page=forearm.html&&cart_id=2864642_24290). I have purchased an ARMS #45C SIR forearm to install on this upper. I have to replace the BMAS barrel nut with a standard barrel nut and install a Delta ring assembly. I have purchased a vise action block to secure the receiver assembly and also a combination barrel wrench from Brownell's. I know that I will need also some moly lube for the threads on the nut. What I need now are suggestions and recommendations on anything else that I need or may need. This is the first time that I am removing a barrel but I am good at mechanical things so I shouldn't have trouble in that area. I just need someone to check me to make sure I haven't forgot anything. Thanks.
Link Posted: 10/20/2003 8:35:59 PM EST
you need to remove a ff handguard from your upper? just trying to clarify this as you don't need to remove anything to install a SIR unless it's the M version. if the ff tube isn't worth much i'd dremel the bast%^d off. but that's just me. [:D] if it is worth it (to sell or whatever) someone else will give you better advice.
Link Posted: 10/20/2003 8:46:17 PM EST
I have to remove the ff handguard because the barrel nut that it uses would not allow the ARMS #45C to fit. So I have to remove it and install a standard barrel nut and delta ring assembly.
Link Posted: 10/21/2003 12:54:02 PM EST
hell, i'd just sell it and buy a new upper. trade it on the EE or something. but i'm lazy like that.
Link Posted: 10/22/2003 8:20:11 PM EST
Sounds like you have everything, you might want to grab a few gas tube retaining pins (roll pins) they can be reused but sometime flare when removed and installed. I like the 1/16" punch to realign my gas tubes with sight housing. The roll pin holder set is nice but not a requirement. Watch those friggen small blind holes on the sir, the screws are "captured" so it is difficult to see the alignment when starting these small friggin fine threads. Snap ring pliers for delta ring also a luxury not a nessesity. Email if there is problems, always willing to help a ar15'er Robert
Link Posted: 10/22/2003 8:41:23 PM EST
Thanks for all the suggestions. I got my SIR in today. The barrel nut came of quite easily and the new barrel nut went on easily also (I was very surprised at that). I was able to torque to 35 lbs and then had to turn the nut just a slight bit more to line up one of the barrel nut grooves with the receiver gas tube hole. I attached the SIR, secured the screws and I am good to go. The SIR is abso-fricking-lutely amazing. Super high quality and extremely stable and strong. The main reason I decide to buy a SIR is because the FF forearm that I had would shift because the jam nut that was supposed to keep if from moving would always come loose. I wanted a very solid FF forearm and the SIR fits the bill. Thanks alot.
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