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adding m4 feed ramps to barrel
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm. Share it in the comments section. AR Tech Tip - Checking M4 Ramps for overhang School of the American Rifle 84.8K subscribers Subscribe 2.9K 90K views 2 years ago AR Tech Tip - Checking M4 Ramps for overhang Show more Show more. Featuring hand lapped 1/8 twist rate button rifling and M4 feed ramps barrel extensions, the 410 stainless barrel gives the shooter the best balance of weight and accuracy. You can put a M4 barrel and non-M4 receiver together, but you can't mismatch them the other way. Does it make a big difference? By my estimates, the tip of the bullet first hits the barrel extension about 1/3 of the way up the respective feed ramp on the barrel extension. So I'm working on my first build, and I'm a little confused. Barrel Length: 16" Barrel Material: 4150V Chrome Moly Vanadium Steel Barrel Finish: Phosphate Barrel Profile: M4 Chamber: 5.56 NATO Twist Rate: 1 in 7" Extension: M4 Gas System: Carbine-Length Gas Block Type: Low Profile .750" Diameter Upper Receiver: Forged 7075 T6 Aluminum Receiver Style: M4 Flat top with feed ramps Receiver Finish: Hardcoat Anodized Dec 17, 2020. I've modified barrel/receivers even before M4 cuts came out and done some receivers when the barrels had cuts. Thread: Adding M4 feedramps to A1/C7 upper. I am having a tough time finding an in-stock barrel (18 or 20 incher) with a rifle extension on it. Modern Series Barrels. Thats why AR10s- And Scar heavies exist for. M4 16", SBN, 1:7, 5.56 NATO Barrel Specifications: - Caliber: 5.56 NATO (.223 REM) - Gas Tube: Car Add to Cart. You absolutely do not want it the other way around however. 5. No need to alter the upper. They are also 1/7 twist, 4150 steel, chrome lined, and button rifled like the real deal! Come join the discussion about racing, builds, pro mods, hot rods, events, turbos, nitrous, superchargers, and more! I notice that's a Gibbz (or Gibbz-type) upper. The barrels also had to be modified. M16's fed pretty well before the M4 feed ramps were introduced. ago Costs about $40-50 to have the feed ramps reprofiled from what I can gather. I've been thinking about doing sort of an "Early Diemaco C8 carbine" clone build with a C7 style upper receiver. Which Model Colt 1911 is For Me? By accepting all cookies, you agree to our use of cookies to deliver and maintain our services and site, improve the quality of Reddit, personalize Reddit content and advertising, and measure the effectiveness of advertising. This includes M4 feed ramps, barrel nut, front sight tower and sight post, and -28 threads for a muzzle device. So, what youre saying is that an M16 upper (not M4 cut) will work with either barrel, but an M4 cut upper will only work with an M4 cut barrel. The barrel extension and the receiver both have to have the cuts. Get The Best Trigger Pull Gauges To Make Every Shot Count. A4 Complete Upper Receiver. I think your mistaking that with adding ramps to the receiver. pm me at BOG or PG, or get in touch with my number 09177542777 if you're interested. I would just make sure to order rifle upper with rifle barrel extension or M4 upper with M4 barrel extension. Mil-spec is good for the masses, and if you want the job done it is a great start. This is why you can use a barrel with an extension with M4 feedramps with a receiver that does not have feedramps, but you cannot use a receiver with M4 feedramps with a barrel with an extension with rifle feedramps. Powered by Invision Community, M4-style barrel extension with Rifle-type upper. AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types. Sorta. From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm. and add them to non-m4 barrels.? How long your barrel "lasts" depends on what your accuracy threshold is before you decide it is too bad to keep using. Good call. By the time you made it work you spent more time, money, and effort than if you just bought a new barrel or upper. If this is your first visit, be sure to I will check with compass lake. Semi autos run slower than full autos. Earlfillmore 13 hr. Guess what? can you buy feed ramps individually? In this episode of Gun Stock Reviews, we look at the difference between M4 Ramps and the old standard ramps of the past. I'd get jams from bullets hitting the back of the upper so I took a small round file and made the M4 ramps in the upper. Change the angle so that the ramp ends at the exact same point. Finding the proper upper receiver is your best option. This includes M4 feed ramps, barrel nut, front sight tower and sight post, and -28 threads for a muzzle device. By rejecting non-essential cookies, Reddit may still use certain cookies to ensure the proper functionality of our platform. Press J to jump to the feed. The barrel is supposed to have the M4 feed ramps. Upper Receiver, A4, Flat Top, USGI, Numbered, AR-Stoner Upper Receiver Stripped AR-15 A3 Flat-Top Matte, Black River Tactical 16 Cold Hammer Forged Optimum Barrel Accuracy Evaluation. Looking to spend $180-250 (depending on condition, forge mark and if a rear sight is included or not.) FN AR15 barrels are hammer forged using the same proprietary high-grade Chrome Moly Vanadium steel used in FN's venerable machinegun barrels produced to handle the punishment of . The upper I want to rebarrel is modified for Service Rifle competition so it's not quite as cheap as buying another $89 upper from Aero. I cant advise on that one folks. from my service in the 70s to my personal weapons, all of my ARs are early 1970 slab sided Colt SP1s. Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more. Clear editor. Upload or insert images from URL. M16s and M16-A1s run at 750 rounds per minute in full auto. That puts the cartridge in a position where the extended feed ramp improves the breech-loading design. SKU: BCM-URG-M4-16 Features: M4 Feed Ramp Barrel Extension Caliber: 5.56 NATO Barrel Length: 16in Barrel Style: Standard Handguard: None BCM M4 Handguards (Double Heat Shield) - Black + $15.00 PKMR (Polymer KeyMod Rail) Carbine Length - Black + $24.95 PKMR (Polymer KeyMod Rail) Carbine Length - Flat Dark Earth + $24.95 Stock Status: Out of stock I wont buy a barrel that isnt a wylde 223 556 but Im only now noticing. Will my A3 upper reciever work with my M4 barrel extention.According to some or your posts they will.Thanks Bill. For this test, I used a Colt upper with M4 feed ramps and a SOCOM heavy 14.5 barrel, just like what is used in the military. I had seen these pix years ago and dismissed the idea of mix and match. . Home Firearms Figuring Out Feed Ramps. To measure just where the round makes impact on the feed ramps, I did not use any sort of micrometer to measure. In most cases the ramps only help during full auto mode while cycling at a high rate. Olympic Arms Upper receiver with rear sight assembly and forward assist and dust cover has M4 feed ramps $260 View attachment 1016575 View attachment 1016576 April 23, 2014 in Rifle - Technical. We want you, our readers, to be able to make informed decisions. You wrote that much to make a point that should have taken about 100 words? Everything that you have on your side to make any weapons more reliable and work when it absolutely needs to is a plus. The M4, and the CAR-15, before it have had similar problems like the ones you mentioned. A closer look at uppers and barrel extensions. aaargh.. that's the setup I hate to see. Either way is good and both types work great with semi auto only guns. One of the AR15 engineers under Gene Stoner pretty much said that the M4 isn't a good platform, especially once the gas port erodes a bit. If your magazines are set up correctly, and the feed lip edges polished smooth, each round fed from the magazine will go directly into the chamber. While I've got everything apart, I'm thinking I just want to put an M4 barrel extension on. If a barrel comes with the feed ramps could I take them off? I bought a .458 upper to go with it, with the extra internal clearance cut before anodizing. No feed ramps. Brevity matters. Press question mark to learn the rest of the keyboard shortcuts. A forum community dedicated to drag racing drivers and enthusiasts. In short, if you have a Dremmel you can do it yourself. Paste as plain text instead, I can still use the combination. If you aren't 110% comfortable with doing the job, and you do not have all the tools and equipment to do it properly, then have a smith do it for you. Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. He had more to say and added some more engineer and gun designer speak too. Its also recommended you polish the ramps once youve achieved the appropriate angle. The best case is to have both an upper and barrel that have the feed ramps. I am glad to know that I need to look for changes in design and the differences in the A2 and A4 feed ramp / rails. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Not all mil-spec features advertised on the product information are the real mil-specs. Damaged Ak front end Barrel in Trunnion with or without sight bases. The best case is to have both an upper and barrel that have the feed ramps. I can probably get the upper reciever first. The Shooter's Log, is to provide informationnot opinionsto our customers and the shooting community. I've thought about it myself, and I'd like to see test results if any exist, displaying what reliability effect M4 ramps have on other barrel lengths. But, as with anything else, this work can go too far. Please allow 5~10 days for assembly and testing before ship date. Use this M4 Barrel extention with M4 feedramps. I will attest that a rifle upper and a barrel with the M4 feedramps works just fine. Remember less is more, little by little. There are several, but Steve and the guys at ADCO in OH are one such option (they use the Dremel method, but they do it right as I have seen several first-hand examples of their work and its performance after the fact). Feedramps, proper staking of castle nuts, forward assist (yep went there)S-happens seen it. M4 can better explain their benefit, although they help with more reliable feeding. Is it kosher to add M4 feed ramps to a standard upper to match an m4 ramped barrel? I have seen it done many, MANY times and if done right, it works/functions 100% without issue. BrianEnos.com Im an old vet, now retired and looking to build some ARs as a hobby to keep me doing something that I will enjoy. If it was some flat top + 16" FSB barrel id just swap upper/barrel, but this is a little more challenging to do that with. Looking for a black stripped A1 upper with non m4 feed ramps (just realized the upper I have wont work with my barrel). I recently built an AR9 (Glock Mags) that has been running flawlessly for about 3-400rds. So, I had purchased a 458 upper. By Proper maintenance and lubrication. Here's some info from Randall Rauch aka www.ar15barrels.com, if your barrel extension has M4 ramps you should have an upper receiver also with the ramps. I'm a machinist in the aerospace industry and lucky enough to have unrestricted access to a really nice machine shop so the modification from rifle to M4 feed ramps is no sweat, I've done it once before a few years back with a .250" carbide cutter in the mill for a friend and it came out looking indistinguishable from a true M4 extension. However Ive built numerous ar15 and lr308 rifles and pistols. Product Details Douglas 18" Flat Dark Earth Cerakoted 416 stainless steel barrel with 1-7 twist and M4 feed ramps. These Mil-Spec M4 feed ramps are part of the original CNC manufacturing process. I wouldn't be concerned at all with any wear after modifying an upper receiver. upper recievers and barrels are hard to comeby. I'd get jams from bullets hitting the back of the upper so I took a small round file and made the M4 ramps in the upper. Does NOT include pin By using the M4 feed ramps for your firearm, you could pick up an increased percentage of the rounds, and feeding reliability would be improved. Your discussions, feedback and comments are welcome here as long as they are relevant and insightful. - The Shooter's Log, 2012 SHOT Show Special Report: Del-Ton TRX Rifle and More! Somwhere in the 1990s I believe, Colt designed the M4 feed ramps, where they took some of the material out of the upper receiver, cut two little ramps in it and then cut the ramps in the barrel extention a little further forward. So there's a lot more going on with rounds bouncing up and down in the mags etc. are all barrels w/ m4 feed ramps?? Press question mark to learn the rest of the keyboard shortcuts. I don't have much to add re: feed ramps, but. Most of barrel assemblies and upper receivers on the market now have a present of M4 feed ramps. Any use of this content without express written consent is prohibited. Description. This 20" BCM barrel is machined from SS410 stainless steel. This USGI modification was done to both the barrel extension and the upper receiver, creating a longer and steeper feed ramp. Again, youll find plenty of videos on spooling up hand grinders to remedy feed ramp and ejection port issues with these larger cartridges, but I strongly suggest going factory-done aftermarket. We have four combinations here: If you consider this article useful, share it with anyone in need! Experts advise on 31 degrees+30 minus-zip. With the increased use of larger-diameter cased cartridges, the M4 feed ramps are proving their values when using them in those cartridges. They are better! M4 Feed ramps on barrel extensions are a solid example. Create an account to follow your favorite communities and start taking part in conversations. I read in Bravo company that there are 2 kinds of flat top upper. Those ramps line up with the barrel, which are cut deeper than on a rifle barrel. First, the M4 barrel and non-M4 upper isnt likely to cause issues, but due to the relief cut on an M4-spec upper, there will be a gap that works like an edge that most definitely can snag the bullet and stub the round. Full M4 feed ramps are on both the upper and barrel extension. so it is better to have an upper reciever that's designed for non-m4 feed ramps since you can put in standard barrels right? . AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own. AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types. 4. Either way is good and both types work great with semi auto only guns. All comments are held for moderation and will appear after approval. Create an account to follow your favorite communities and start taking part in conversations. I was planning on using a Daniel Defense 14.5 pencil barrel, because like the C8 they are CHF, lightweight profile, and .750 at the FSB (And also because quality carbine pencil barrels with .625 gas blocks seem to be in short supplyor else I'd just build a 723 clone.) . By my estimates, the tip of the bullet first hits the barrel extension about 1/3 of the way up the respective feed ramp on the barrel extension. It's not worth changing the barrel extension on an already finished barrel, getting the new barrel extension to line up correctly with the gas port will probably cost more in gunsmithing/machining fees than buying a new barrel. Given that most of us dont always have perfect access to truly genuine Mil-Spec, mil-standard parts (those actually used in issued fighting tools), were shopping based on a little part trust and a bigger part knowledge. You need to match up barrels to receivers for optimum performance. Rear side of a CZ-75B pistol barrel showing the (here dirty) feed ramp. For someone who is new at trying to understand feed ramps it helps to read a couple different explanations. You want them to match. And it appears that the bolt is slamming into the top of the bullet. Some gun owners believe that the M4 ramps can help for some of the larger-diameter cartridges in use. They were not intended to be super long range man killers. Just put it in and shoot it. This can lead to a rare but odd situation; barrel and receiver mismatch. It's an interesting question. It may not display this or other websites correctly. The magazine lips cannot move, so with these larger diameter cartridges, the bullet tips down lower about the centerline of the bore (half of the diameter increase to be exact). All Rights Reserved. Try this little exercise: 1. However, if youre wanting to rebarrel a non-M4-cut upper with an M4 feed-ramp equipped barrel, or going the other direction: you have a new upper thats been relieved to fit with the M4 ramps, and a non-M4-cut barrel extension, and that wont work! Issues can arise when receivers and barrel extensions are mismatched. #2. Thats receivers, bolts, and on down the list of the 100 or so parts that can make up an AR-15. which is basicallly an m16a1 cut down. They guide the bullet up and into the chamber. However, I have seen more than a few basement gunsmith hackjobs using a dremel, some Jack Daniels/liquid courage, and an unsteady hand that have made a total, unrepairable mess of the job. Is one better than the other? which is bad combo. 308 m5 using m4 feed ramps, which I belive are for the smaller round like. Don't forget read more information about it here! In general, all you need to understand is that the M4 feed ramps include the barrel extension and upper receiver. Costs about $40-50 to have the feed ramps reprofiled from what I can gather. For a better experience, please enable JavaScript in your browser before proceeding. I've seen several places say you just need a 1/8" chainsaw sharpening bit and a Dremel to fix it. For instance I was looking at the BCM upper receiver, and it said it had M4 feed ramps machined into the upper. The barrel blanks available are made from 416 Stainless Steel. Can someone recommend or point me in the right direction of a good quality upper receiver for an SPR build that does not have M4 feed ramp cuts in it? There is a picture of the various options, hopefully another poster can link them. You CAN modify a rifle/A2 barrel extension to an M4 style extension, but it isn't always the best way to go unless you just have to do it. i have the rifle barrel. Most work performed while-you-wait, evening and saturday appointments available. On the other hand, I wouldn't consider them as a deal breaker, and they would not pass up a good deal with an upper only because it did not have them - the M4 feed ramps. M4 extension with .350 M4 style feed ramps 11 Degree Target Crown Threaded Muzzle 5/8"x24 TPI Weight: 26.5 ounces The only one I found is LaRue's upper, but it won't work with the hand guard I'm using (Geissele MKIII). If I can correct an issue before it's an issue that is preferred. With a larger diameter case body sitting down in the magazine, the tip of the bullet sits lower in relation to the chamber/bore centerline than with a .223-size round. All things being equal and having used both weapons extensively, Id rather have the feed Ramps. so im thinking I might as well just get the unramp upper. May 17, 2008 in The Armorer. Was sort of worried about how it would run with an 11.5" barrel and mismatched ramps, but it sounds like it should be good to go either way. colt A1E1 733 uppers didn't have extended carbine feedramps ? Powered by Invision Community. A feed ramp is a basic feature of many breech loading cartridge firearm designs. To conclude, the M4 feed ramps bring a lot of improvements to the AR-platform firearms. Feels like a silly question now that it makes sense. Go back to writing school. Its not a big deal but still an important thing to remember and understand. FN AR-15 5.56X45mm Nato . Both. Go slow and you'll be done in no time. AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own. It is a tightly machined and polished piece of metal which guides a cartridge from the top of the magazine into the firing chamber of the barrel. Then you can get a regular rifle barrel for the upper with no ramps. The tip of the cartridge rarely comes into contact with the upper receiver. I think my question would be why rifle receiver+M4 barrel is just "ok" rather than "good", unless the point is that in a carbine-gas gun M4 ramps are just considered an improvement over no ramps. 2. The M4 receiver feed ramps are cut at a steeper angle and, as a result, extend down into the receiver wall. DSA has fat top, Mueller, non feed ramp uppers for $40. Does anyone have a follow up that confirms or denies my claim? The dimensions are different between the two, so theyd have to change some things to the feed ramps dimensions. Now, theres nothing wrong at all with a little polish on any and all feed ramps, which can not only be done fairly easily, it can be successfully done by most at home. 16" Pre-Ban M4 Profile Barrel Assembly CARBINE Gas System About Upper assembly comes completely head spaced and test fired. Rifles, Uppers, Lowers, Barrels, and more, [ARCHIVED THREAD] - Rifle vs m4 feed ramps, http://i135.photobucket.com/albums/q125/PursuitSS/Postings%20photos/c0d26170b75c3e6f9ea65a7d0862247e.jpg. M4 feed ramps were created during the development of the xM4 carbine for the original Army requirement of a carbine rifle that used the then current M16A2 upper receiver, 14.5" Barrel and had featured a collapsible sliding stock. *Must have a registered ARFCOM account to win. BEFORE YOU GO MODIFYING IT, check your headspace.I have a Gibbz upper in my junk drawer because the upper -- for some reason -- wouldn't allow a perfectly good bolt (as checked by Criterion) to headspace correctly on a Criterion barrel, with the bolt installed in the carrier. Anodized red parts. Having been in military supply, I know that what the mil-spec means: it gets the minimum job done for thousands (millions) of parts/systems. What is the difference between Modern, Performance, and Premium Series Barrels? For new construction barrels only. M4 feed ramps are not an original design, they were designed for the M4 In fact, the . instead of mil-spec. It's best to use rifle/rifle combo or M4/M4. Add 3% to the total cost for credit card purchases. It's best to have M4 ramps on both the upper and barrel. Seems like it should work to me, but be a real challenge to keep clean and be damned ugly to boot. While this gun is a more of novelty build than a "serious use" AR, I intend to use good parts and want it to run as well as my other ARs. LanceRiley, Notice how the ramp starts on the barrel extension and not in the receiver. Create Account; Log Out ; Log In ; Wishlist 0; Shopping Cart 0; Home; About Well, over the course of 5,000 rounds at .40 a round, you spent two grand on ammo. Its easier to add feed ramps to the receiver not so easy to add them to the barrel extension. Reliability is the main concern for me when I re-barrel this rifle. Machined from 4150 Chrome Moly Vanadium Steel and feature a QPQ corrosion resistant finish and QPQ coated M4 feed ramp extension. You cannot paste images directly. 338 and others not the .308 76251 or 6.5 creedmore which o think should have a.30cal feed ramp.? "A Bad Day At The Range Is Better Than A Great Day Working". If you have a m4 ramped upper but not barrel you can cause problems as there's a lip of steel barrel extension in the way that can cause feeding problems. EDIT: Okay, I understand now! The mil actually only specs M4 feed ramps for use in its M4s. Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. And that is the important thing! Some barrels I see for sale say they include M4 feed ramps, and some uppers say they include them too. I have done the same, protect the Barrel extension with a layer of electrical tape and carefully file or Dremel the ramps into the aluminum receiver. However, they do have M4 feed-ramps which is not clone correct. Recommend using a gunsmith this route too if you are not comfortable. An older-version (or A2-style) feed ramp is cut only on the barrel extension itself (top). CARBON-15 Stripped Lower Receiver Amazing what happens in a thread over a simple question. "It will last 5k rounds instead of 4k. You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers. Gun smith said , not head spaced properly. Just because you can, doesn't mean you should. We reserve the right to edit as appropriate, delete profane, harassing, abusive and spam comments or posts, and block repeat offenders. Oh well, as I tell my lovely and understanding bride, guns are relatively free. it's the ammo and training that cost real money. I'm planning on replacing my forearm with a Larue 13.5. Notify me of follow-up comments by email. You need to match up barrels to receivers for optimum performance. what does it do?? And that the M4s and M4A1s are issued M855 which has a slight difference in bullet shape vs. the older 55gr M193 BALL. I picked up a side charging upper from Sundevil last year. There's a 7 degree difference between standard and M4 ramps. Founded by Frank Galli in 2000, Snipers Hide has been offering informational videos, podcasts, and other support to its users in one location. The M4 was the first (allegedy) carbine length gas system. The rifle receiver, doesn't have ramps on the receiver, they are only cut into the barrel. Man, its crazy how many of yall have absolutely no idea why you do what you do. If you have a bolt that you would like to use you are welcome to ship it to us for accurate headspace. In military situations, it is advantageous for rifles to function with damaged, worn, or less than ideally serviceable magazines. Copyright 1996-2023 AR15.COM LLC. practical_man Add M4 cuts to Barrel Ext $15.00 We can modify your rifle extension to match the M4 cuts in an upper receiver. If I was concerned with precision, I would seek out parts from well-known gun makers and customizers Baer comes to mind, Hart barrels, etc etc. I'm assuming that you only need the ramps from one or the other. Ok, So, in short, I've got a barrel on my Armalite upper (with M4 feed ramps in the upper) that has standard AR-15 (non-M4) ramps. There is no way to make a carbine barrel extension out of a rifle barrel extension, period, full stop. Its highly recommended to put any AR-platform firearm together with a matching M4 barrel extension and upper receiver set. I got my help from this thread, and thank you again to ORD. The first reason is that they are, indeed, better. I think you will find that the tip of the bullet clears the M4 cuts in the upper receiver by a wide margin. They provide a lower, wider, and smoother entry for any round of ammo, whether its necessary or not. On AR9's, I understand the distance between the Mag Follower and the Feed Ramp is a known complication in the design. Its a miracle! All uppers are assembled cleaned and tested before shipping. Copyright 1996-2023 AR15.COM LLC. well.. it's kinda hard to get stuff in this part of the world. The M4 ramps, if I am not mistaken, were originally made to help reduce malfunctions on the M4 carbine. For a better experience, please enable JavaScript in your browser before proceeding. By I've seen uppers with and without anodizing on M4 ramps . it seems to me to be about 50/50 with and without. http://www.ar15fornoobs.com/wp-content/uploads/feedramps.jpg. All NFA rules apply. Being a Newbie AR owner ((Ive been an avid gun owner for nearly 50 years), I appreciate the information and visual aids that Im sure will be a big help in enjoying and using this gun platform. The M-16/M4 are great weapons. By rejecting non-essential cookies, Reddit may still use certain cookies to ensure the proper functionality of our platform. check out the. M4 Barrel Extension (M4 Feedramps) $22.95 (4 reviews) SKU: Barrel-Extension-M4 Stock Status: Quantity: Add to Wish List Description For your AR15, M16, M4. You can always buy a non-m4 extension and have the new barrel retimed and headspaced, but it will probably cost more than a new upper receiver. An upper without feed ramps can be used with a barrel that has them as the majority of the ramp is on the barrel extension. Some suggest taking a grinder to the extension area. 's blog. Site towers are not "F" marked SPECS: Length- 14.5". The upper is designed to have two levels of top rails for mounting of night vision in front of scopes. This is a big tip, by the way, for pistol-caliber ARs. if you are OK with 3MOA, you might go 20,000 rounds! Thanks! Buy AR 15 16" .350 Legend Nitride M4 Profile Barrel 1:16: GunBroker is the largest seller of AR15 Parts Gun Parts All: 974000728 .