Knowledge Base - Topic : Questions Regarding Upper Receivershttp://www.bushmaster.com/faqs/afmmain.aspxWelcome to our knowledge Base Center. Here you will quickly find answers to some of our most commonly asked questions.FAQ # 2699 : Has the barrel for the 6.8 upper always been SpecII or did it used to be SAAMI? Has the barrel always been 1:11 or did it used to be a different twist? Thankshttp://www.bushmaster.com/faqs/?f=2699Thu, 09 Sep 2010 00:00:00 GMTFAQ # 2695 : I have the XM15 E2S with a 16" barrel i am using the midwest industries picatinny for grips and yankeehill front folding sight with bayonet lug. Will the piston conversion fit/work with they 2 mods?http://www.bushmaster.com/faqs/?f=2695Tue, 07 Sep 2010 00:00:00 GMTFAQ # 2574 : Will a bushmaster 6.8mm upper fit on a S&W M&P15 lowerhttp://www.bushmaster.com/faqs/?f=2574Sat, 10 Jul 2010 00:00:00 GMTFAQ # 2557 : I have a Bushmaster M4A3 carbine with removable carry handle. I think this is a stupid question, but how do you remove the "removable" carry handle? Do I need any special tools to do this?http://www.bushmaster.com/faqs/?f=2557Thu, 01 Jul 2010 00:00:00 GMTFAQ # 2548 : Can your .308 rifle be converted to a .223 by simply changing out the upper and putting a magazine block in the magazine well?http://www.bushmaster.com/faqs/?f=2548Tue, 29 Jun 2010 00:00:00 GMTFAQ # 2533 : CAN I BUY A COMPLETE UPPER ASSEMBLY IF I LIVE IN CALIFORNIA.http://www.bushmaster.com/faqs/?f=2533Tue, 22 Jun 2010 00:00:00 GMTFAQ # 2503 : I have a Bushmaster Model XM15-E2S. Will the 7.62x39mm Carbine M4 Type Upper Receiver will fit the lower receiver of my AR?http://www.bushmaster.com/faqs/?f=2503Fri, 04 Jun 2010 00:00:00 GMTFAQ # 2497 : I purchased a BURA3B-16F upper assembly from Midway. It arrived with no manuals or paperwork other than the invoice from Midway. The Midway stock number is 935289. Are there any markings on the upper assembly to let me know this is a Bushmaster upper? How do I know I got the real thing? Thanks, Georgehttp://www.bushmaster.com/faqs/?f=2497Wed, 02 Jun 2010 00:00:00 GMTFAQ # 2482 : I have a Bushmaster 20" A-2 purchased new in late 1999. Looking to replace upper receiver with A-4. Did this model come with A-4 Feed Ramps/barrel? Just want to make sure new receiver is compatible with original barrel etc...Thank you.http://www.bushmaster.com/faqs/?f=2482Wed, 26 May 2010 00:00:00 GMTFAQ # 2481 : I would like to mount a Bushmaster AR 15 flattop to a Colt M16A1 Full Auto lower. Is this possible without many alterations or do I have to change the bolt and buffer spring as well?http://www.bushmaster.com/faqs/?f=2481Tue, 25 May 2010 00:00:00 GMTFAQ # 2450 : we just bought a bushmaster upper 6.8spc and went and bought a box of Remington ammo . the problem is it won't eject the shells after they are fired you have to manually eject them I check to make sure that the gas block was not plugged and even put a vacuum hose on the gas tube while it was installed and blew threw it with no problems what else can it be I read that some ammo has this problem but at 35.00 a box you think it would be good stuff http://www.bushmaster.com/faqs/?f=2450Thu, 06 May 2010 00:00:00 GMTFAQ # 2445 : I just recently acquired a 6.8mm SPC bolt carrier group but the firing pin is missing. I hear the bolts are different, but can I use a firing pin from a 5.56mm on a 6.8mm bolt?http://www.bushmaster.com/faqs/?f=2445Wed, 05 May 2010 00:00:00 GMTFAQ # 2419 : Will your C15 P21 pistol parts interchange with my Professional Ordnance, Inc. Carbon 15 Pistol? I need bolt an carrier,charging handle an buffer spring for my Carbon 15 Pistol.http://www.bushmaster.com/faqs/?f=2419Fri, 23 Apr 2010 00:00:00 GMTFAQ # 2418 : i have a bushmaster m4 with 16 inch barrel and collapsible stock. Can i put a 20 inch upper on my lower reciever.http://www.bushmaster.com/faqs/?f=2418Thu, 22 Apr 2010 00:00:00 GMTFAQ # 2417 : What is the sight radius of your 20" and 24" National Match Target Model Upper Receiver/Barrel Assembly?http://www.bushmaster.com/faqs/?f=2417Wed, 21 Apr 2010 00:00:00 GMTFAQ # 2404 : I have ordered a 450 bushmaster upper that I wish to put on my CAR 15 lower unit. Is it possible to obtain the upper with an unthreaded muzzle and no brake or flash supressor - simply a crowned muzzle?http://www.bushmaster.com/faqs/?f=2404Thu, 15 Apr 2010 00:00:00 GMTFAQ # 2401 : Can you please explain the main differences in these 2 bushmaster uppers, thanks. Model: PUR VMB 20PRED 8 Model: PUR VMB 20FPRED 8 Thank you for your timehttp://www.bushmaster.com/faqs/?f=2401Wed, 14 Apr 2010 00:00:00 GMTFAQ # 2386 : Hello, What is the lead time on your complete uppers? Specifically, I was looking at a PURVMB 24FVAR9 Thank You, Kenhttp://www.bushmaster.com/faqs/?f=2386Thu, 08 Apr 2010 00:00:00 GMTFAQ # 2382 : I am looking at buying a Bushmaster AR-15 caliber 7.62x39. Using the lower receiver of that rifle, would I be able to use a .223 upper receiver so that I would have the option of using either caliber?http://www.bushmaster.com/faqs/?f=2382Wed, 07 Apr 2010 00:00:00 GMTFAQ # 2357 : RE: 3 rail gas block. I have a First Samco FAS-2 detachable mount for my Surefire 6P flashlight. It fits on Weaver sight bases but it will not fit on the rail on the gas block rail on my rifle. Why not? http://www.bushmaster.com/faqs/?f=2357Sun, 28 Mar 2010 00:00:00 GMTFAQ # 2278 : my gas key shows some rough edges do I need to replace it? What do you mean by staking the key?http://www.bushmaster.com/faqs/?f=2278Sun, 28 Feb 2010 00:00:00 GMTFAQ # 2268 : I am looking at purchhasing a new bushmaster complete bolt & carrier assembly, what is the difference between ar15 and m16 options? How do I know which to get?http://www.bushmaster.com/faqs/?f=2268Thu, 25 Feb 2010 00:00:00 GMTFAQ # 2265 : i have model xm15-e2srifle 20 inch barrell can i convert to a 16inch carbine upper an keep my lower?http://www.bushmaster.com/faqs/?f=2265Wed, 24 Feb 2010 00:00:00 GMTFAQ # 2254 : what are the markings of authentic flat top upper receiver of a real bushmaster?http://www.bushmaster.com/faqs/?f=2254Sun, 21 Feb 2010 00:00:00 GMTFAQ # 2232 : I have a bushmaster model xm15-e2s serial number L370648. Can I buy an A-3 upper receiver from bushmaster with all the parts insided so all I have to do is remove the old upper receiver and place the new one on. I was thinking that the 14.5" M4 or the 14.5" heavy Barrel A3 models would work with my lowere receiver with out any other part changes. Will they accept the bolt I have now?http://www.bushmaster.com/faqs/?f=2232Sun, 14 Feb 2010 00:00:00 GMTFAQ # 2229 : If I place the 20" predator upper on a lower with a collapsible carbine butt stock and buffer will it function properly? Or I could ask it the fore mentioned upper tuned to a rifle butt stock and buffer? Thanks for the answer in advance.http://www.bushmaster.com/faqs/?f=2229Sat, 13 Feb 2010 00:00:00 GMTFAQ # 2214 : If i buy a new V Match "Flat-Top" upper reciever do i need a smith to put the barrel and other parts from my current upper or can i do it myself?http://www.bushmaster.com/faqs/?f=2214Thu, 04 Feb 2010 00:00:00 GMTFAQ # 2213 : Regarding your new 6.8 SPC SPCII 1/11 Upper assy which I never knew you offered, why can I not find ANY information anywhere on this? I just purchased one over the phone with your sales dept for my BM M4A3 lower. They assured me it will be the SPCII 1/11. Can I be assured of this and when do you expect literature and website info/specs to be available? The guys at the 68Forums.com and AR15.com have no info either and several have been looking for one. I can imaging sales lost due to lack of advertizing the new model. Your most current catalog has little if any spec's info on the old style either. I'm looking forward to this but wish I knew when I ordered it that I could have added the piston retrofit and a rail system. http://www.bushmaster.com/faqs/?f=2213Wed, 03 Feb 2010 00:00:00 GMTFAQ # 2196 : Will the mags for the 6.8 upper receiver work and fit in the 223 lower receiverhttp://www.bushmaster.com/faqs/?f=2196Wed, 27 Jan 2010 00:00:00 GMTFAQ # 2190 : I bought a 16" M4 profile 6.8 mil upper from bushmaster, and I want to put the gas piston retrofit conversion kit on this upper. Is this possible and do I have to specify the barrel length in the order? Is this a standard barrel? http://www.bushmaster.com/faqs/?f=2190Sun, 24 Jan 2010 00:00:00 GMT