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The barrels also had to be modified. Its fine to use an M4 Barrel with a non-N4 (rifle) upper but if you have the barrel already is much simpler to just buy a M-4 upper and just replace the upper the barrel is harder to build..I have even cut ramps on a rifle upper and it really wasent needed That is before I knew better.Then I guncoted the ramps before I found out about Aluminum Black treatment. *Must have a registered ARFCOM account to win. I like getting another Upper idea then you could end up with two rifles! I have a non ramped barrel in a ramped upper, feeds fine. You need to match up barrels to receivers for optimum performance. Im an old vet, now retired and looking to build some ARs as a hobby to keep me doing something that I will enjoy. 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 Do you have an AR barrel or feed ramp tip? You also repeated yourself. Barrel customizations are also available. A closer look at uppers and barrel extensions. So, an M4 feed ramp includes the barrel extension and the upper. Feed ramps being m4 or. Our 6mm ARC barrel come standard with 1-7.5 Twist, M4 Feed Ramps and gas tube. [ARCHIVED THREAD] - M4 feed ramp barrel in a non M4 ramp upper. Looking to spend $180-250 (depending on condition, forge mark and if a rear sight is included or not.) May 17, 2008 in The Armorer. Now move move the on deck cartridge forward to the 3/8 of inch position and again note the position of the tip of the bullet in relationship to the barrel extension. The information provided here does not represent the views of Cheaper Than Dirt! 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. If you ever have an issue, then look at getting a correct barrel for the upper. I had seen these pix years ago and dismissed the idea of mix and match. Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more. 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 All NFA rules apply. Since the M4 barrel is one and a half inches shorter than the minimum legal barrel you can install in an AR15, the M4 gas tube will be, of course, smaller. I cant advise on that one folks. I guess it depends on what your relationship to the necessary shop activities is. A feed ramp is a basic feature of many breech loading cartridge firearm designs. I bought a .458 upper to go with it, with the extra internal clearance cut before anodizing. It has ran flawlessly (barring tuning of the gasblock when new) with several different brands of magazines and ammo. 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. For a better experience, please enable JavaScript in your browser before proceeding. Does it make a big difference? Powered by Invision Community, M4-style barrel extension with Rifle-type upper. Barrel, sight and trigger work on most pistols and shotguns. 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. Rifles, Uppers, Lowers, Barrels, and more, [ARCHIVED THREAD] - Rifle vs m4 feed ramps, http://i135.photobucket.com/albums/q125/PursuitSS/Postings%20photos/c0d26170b75c3e6f9ea65a7d0862247e.jpg. So, what is the difference between M4 feed ramps and regular ones? And that is the important thing! Your link has been automatically embedded. Caught a deal on a matched barrel and bolt. M4 feed ramps are not an original design, they were designed for the M4 In fact, the . Instead, I just loaded up each mag with two rounds, and pushed the rounds forward by hand until the tip of . A couple of times I ended up with the OK set up from the picture above. Lol. I have a 723 build (w/ C7 upper) and a 727 build (A2 upper) that use 14.5" Colt M4 barrels. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. The rifle-platform M16s dont use them. I wouldn't be concerned at all with any wear after modifying an upper receiver. If your upper isn't showing signs of bullets rubbing on the aluminum under the barrel extension, you should be good with M4 ramps. Full M4 feed ramps start on the upper and continue onto the barrel extension. and add them to non-m4 barrels.? I've seen that pic, it is a good reference. Gun smith said , not head spaced properly. The barrel Throat is the second most critical component after angles and should be polished with utmost care. To conclude, the M4 feed ramps bring a lot of improvements to the AR-platform firearms. The last is using the best and right ammo for the job. An older-version (or A2-style) feed ramp is cut only on the barrel extension itself (top). Founded by Frank Galli in 2000, Snipers Hide has been offering informational videos, podcasts, and other support to its users in one location. On AR9's, I understand the distance between the Mag Follower and the Feed Ramp is a known complication in the design. instead of mil-spec. Ar-15 Manufacturers Should Be Avoided: Which Should You Buy? However Ive built numerous ar15 and lr308 rifles and pistols. Looking For Bear Creek Arsenal Barrels Review? So there's a lot more going on with rounds bouncing up and down in the mags etc. pictures would help. #2. This includes M4 feed ramps, barrel nut, front sight tower and sight post, and -28 threads for a muzzle device. Most of barrel assemblies and upper receivers on the market now have a present of M4 feed ramps. 2. 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? When carrying out feed ramp polishing, it is crucial to prioritize the frame's angles, which is a critical part of the feed ramp. 30 cal. Hasn't misfed yet, through initial break in up through 1k rounds, and that's mag length ammo. I replaced the M4 feed ramp barrel with a monolithic feed ramp barrel and no more problems. From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm. This gave it a longer point for the magazine to allow the rounds to come out of the magazine and feed into the chamber. "C" stamp and CAGE code available. My experience with ARs is all A-1s. Costs about $40-50 to have the feed ramps reprofiled from what I can gather. But, as with anything else, this work can go too far. 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. It's best to have M4 ramps on both the upper and barrel. Please allow 5~10 days for assembly and testing before ship date. I didnt think anything about it having M4 feed ramps. Display as a link instead, Regular feed ramps are cuts into the barrel extension only, which allows guiding the round into the chamber during loading, making them a fundamental feature of many breech-loading firearm designs. By the time you made it work you spent more time, money, and effort than if you just bought a new barrel or upper. 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. Barrels are Douglas 416 stainless steel with 1-7 twist with M4 feed ramps Additionally, in this increasingly specialized world of AR-15 parts that we live in, there are proprietary feed ramp cuts used for some alternate cartridges, such as .458 SOCOM. Seems counter intuitive to recommend an M4 cut upper, especially if the barrel Im looking at has the rifle feed ramp (not M4 cut). What is an m4 feed ramp? If you consider this article useful, share it with anyone in need! 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. Feed ramps on barrel extensions are a good example. I too built a .458 SOCOM carbine . It's best to use rifle/rifle combo or M4/M4. Ready to drop onto a complete lower receiver. Also, barrel life is relative. The Bullet ~ Handguns, Rifles and Shotguns, http://thearguys.com/ar-facts/m4-feed-ramps/. Create Account; Log Out ; Log In ; Wishlist 0; Shopping Cart 0; Home; About So, lets glide down these lines below to erase your misconceptions about them. You will be able to leave a comment after signing in, AR15Armory.com That puts the cartridge in a position where the extended feed ramp improves the breech-loading design. The upper is designed to have two levels of top rails for mounting of night vision in front of scopes. 308 m5 using m4 feed ramps, which I belive are for the smaller round like. Can I use a barrel with M4 feed ramps with an upper that isnt M4 matched? AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own. Then the manufacturer discontinued the barrel. I put together a second AR9 that is having a feeding issue, even if using similar parts as the first one. Related: If you are using a Ar rifle, best green laser sight is good choice for hunting. The M4, and the CAR-15, before it have had similar problems like the ones you mentioned. The barrel extension and the receiver both have to have the cuts. We have four combinations here: Another reason is that any commercial receiver and parts makers want to tool up to make upper receivers and barrel extensions, especially when shorter guns are becoming more popular. Snipers Hide is a community of Snipers of all kinds, focusing on long range shooting, accuracy, and ballistics. Don't forget read more information about it here! Any use of this content without express written consent is prohibited. They . 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. There's no downside to having M4 feedramps on your carbine, but they are not as necessary without full auto and when using followers that will not tilt (or in a 20 AR15). They guide the bullet up and into the chamber. It's best to use rifle/rifle combo or M4/M4. 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. 410 stainless is also harder and more corrosion resistant than conventional 416 stainless found in other commercially available precision barrels. Mil-spec is good for the masses, and if you want the job done it is a great start. We want you, our readers, to be able to make informed decisions. Product Description Surplus Colt 14.5" SOCOM, carbine length gas system barrel from Colt. well.. it's kinda hard to get stuff in this part of the world. The difference between standard feed ramps and M4 ramps is easy to see. Go back to writing school. The angle is going to be key, alot of people attempt to mimic the angle of the barrel feed ramps, this is incorrect. Thanks! M4 extension with .350 M4 style feed ramps 11 Degree Target Crown Threaded Muzzle 5/8"x24 TPI Weight: 26.5 ounces Backing up a ton: Any and all AR-15 barrel extensions have feed ramps. True, which is why they're not even needed in semi autos. Using an upper with M4 feed ramps with a barrel that does not have them will lead to feed problems as it creates a ledge/lip that can catch the bullet tip as it tries to feed. if you are OK with 3MOA, you might go 20,000 rounds! Thanks for explaining the feed ramp topic in a couple of different ways. I don't have much to add re: feed ramps, but. I found the article very informative. You are using an out of date browser. Single Action and Double Action Which One Is Better For You? Either way is good and both types work great with semi auto only guns. However the DD 14.5 are ideally meant to mate up with M4 style upper receiver feedramps. Any use of this content without express written consent is prohibited. aaargh.. that's the setup I hate to see. A couple of times I ended up with the OK set up from the picture above. Shopping with us is absolutely safe - you never have to worry about credit card safety when shopping here Share your latest AR build or photos from the range with #RangeDayFriday for a chance to win a new firearm! In this episode of Gun Stock Reviews, we look at the difference between M4 Ramps and the old standard ramps of the past. 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). Reach in through the ejection port and slide the on deck cartridge about 1/4 inch forward and observe the tip of the bullet in relationship to the barrel extension. Some suggest taking a grinder to the extension area. 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. I checked what I have now. We're a little past that point as I already own both the barrel and receiver, both of which cant easily be replaced or swapped for a decent price. The mil actually only specs M4 feed ramps for use in its M4s. By Yamil Sued August 6, 2021. Semi autos run slower than full autos. I have looked and looked and looked. Clear editor. My alternative plan is to do exactly as you describe. In general, all you need to understand is that the M4 feed ramps include the barrel extension and upper receiver. Higher pressure equte to parts (bcg, buffer, buffer spring, ROUNDS, etc) experiencing much higher wear/tear. Sorta. This Kit is made to cut or polish the STEEL Feed Ramps on your Barrel Extension ONLY. Some gun owners believe that the M4 ramps can help for some of the larger-diameter cartridges in use. Try this little exercise: 1. They are better! Pasted as rich text. is the m4 feedramp common in barrel extensions? Insert the barrel and sharpie the cut area, then use the right bit on a dremel. AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types. Metal cases ammunition such as Wolf through an M4 clone? Good call. . The parts are interchangeable. I would only add the feed ramps to the receiver if I had feeding issues, which you should not have. I suggest you get a rifle receiver. 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. Would not feed to save its life! I notice that's a Gibbz (or Gibbz-type) upper. Remember less is more, little by little. You have the option of barrel type, thread, fluting, finish type and to add a match bolt. By 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. 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. DSA has fat top, Mueller, non feed ramp uppers for $40. It is milled out of 6061 T6. 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. Oh well, as I tell my lovely and understanding bride, guns are relatively free. it's the ammo and training that cost real money. This can lead to a rare but odd situation; barrel and receiver mismatch. This is one time it's better to go a little too far than to leave an edge for the . are all barrels w/ m4 feed ramps?? Its also recommended you polish the ramps once youve achieved the appropriate angle. 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, its rare now to find an upper receiver or a ready-to-go barrel that doesnt have the M4 cuts. For use by barrel manufacturers. Jams and misfires. It's going to a gunsmith to be shortened and rethreaded anyways, can they just grind/polish the feed ramps to match or is it more involved than that? I can assure you that most mods that deviate from the original design aren't 100% reliable. One new winner* is announced every week! You can put a M4 barrel and non-M4 receiver together, but you can't mismatch them the other way. Its not a big deal but still an important thing to remember and understand. Proper maintenance and lubrication. Modern Series Barrels. You can run M4 cut barrels with rifle receivers, but not the other way around as it will create at catch that can hang up the bullets. Little polish. hey bro nice to see you here!!! Please be respectful of others. All Rights Reserved. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Owning Best Ruger SR9c Accessories Can Change Your Life. Add 3% to the total cost for credit card purchases. There are now thousands of upper receivers and ready-to-use barrels that have the cuts of M4 feed ramps. Is it kosher to add M4 feed ramps to a standard upper to match an m4 ramped barrel? Went back to the sellers website and found I was not the only one with problems. Come join the discussion about racing, builds, pro mods, hot rods, events, turbos, nitrous, superchargers, and more! A shorter gas tube means reduced gas pressure, and we all know what happens when there isn't enough pressure to cycle the bolt carrier group properly. 's blog. ago Costs about $40-50 to have the feed ramps reprofiled from what I can gather. The ramps on the regular rifle-type extension are cut just to the edge of the extension. 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 . M4 Feed ramps on barrel extensions are a solid example. The rifle receiver, doesn't have ramps on the receiver, they are only cut into the barrel. The barrel is supposed to have the M4 feed ramps. And that the M4s and M4A1s are issued M855 which has a slight difference in bullet shape vs. the older 55gr M193 BALL. Upload or insert images from URL. Full M4 feed ramps are on both the upper and barrel extension. Dec 17, 2020. I've shot a good deal of rounds through 20" A2's and I realize they run but you are describing issues that the M4 feed ramps alleviate, that would probably be good to reduce on A2's as well. Get The Best Trigger Pull Gauges To Make Every Shot Count. The best case is to have both an upper and barrel that have the feed ramps. In most cases the ramps only help during full auto mode while cycling at a high rate. M4 Feed ramps on barrel extensions are a solid example. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Some argue that, factually, its a step to enable a smoother feeding. pm me at BOG or PG, or get in touch with my number 09177542777 if you're interested. 16" Pre-Ban M4 Profile Barrel Assembly CARBINE Gas System About Upper assembly comes completely head spaced and test fired. I'm a machinist in the aerospace industry and lucky enough to have. Copyright 1996-2023 AR15.COM LLC. As suggested, its best to match the upper and barrel extension no worries that way. BUT, I DO NOT TRUST MY LIFE TO THAT WEAPON. They were not intended to be super long range man killers. M4 M-4 Feed Ramp Jam with 55 gr grain Bullets, Solution, Fix, AR15 AR-15 Stuck Cartridge iowaunemployment 21K views 10 years ago Comparing AR15 barrels -Faxon vs. Bear Creek arsenal-. First of Im not a gunsmith or firearms professional. It may not display this or other websites correctly. Feedramps, proper staking of castle nuts, forward assist (yep went there)S-happens seen it. I'm lookin for a clear definition as to what they are, and what they do to enhance a given rifle's performance? Will my A3 upper reciever work with my M4 barrel extention.According to some or your posts they will.Thanks Bill. It is removeable with a special wrench and a barrel clamp/vise. The M4 style feed ramps and barrel extension provide consistent feeding and the matte black Manganese Phosphate finish resists external corrosion and oxidation. The Shooter's Log, is to provide informationnot opinionsto our customers and the shooting community. Your previous content has been restored. The rifle receiver, doesn't have ramps on the receiver, they are only cut into the barrel. And it appears that the bolt is slamming into the top of the bullet. ago KrinkyDink2 9 hr. The extension is the part at the end of the barrel that fits inside the upper. Press J to jump to the feed. FN AR-15 5.56X45mm Nato . These units actually feature the NON-F-Marked (correct) front sight base. UPPER RECEIVER: AR-15 Mil-Spec Machined out of 7075-T6 Forged Aluminum, M4 Feed Ramps, Cerakoted Magpul Flat Dark Earth (FDE) Color with Forward Assist and Ejection Port Cover Installed BARREL: 22 inch, 223 Wylde Caliber, 4150 CMV, 1:7 Twist, Heavy Bull Barrel Profile, Straight Fluted, Melonite/Nitride Finish - made for us by Tactical Kinetics HAND So, I had purchased a 458 upper. BrianEnos.com 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. I wont buy a barrel that isnt a wylde 223 556 but Im only now noticing. Its highly recommended to put any AR-platform firearm together with a matching M4 barrel extension and upper receiver set. All this basically means is that the ramps continue from the barrel extension down through the upper receiver tonthe magazine. Supposedly you'll only notice issues with rapid/auto fire with a configuration like this. Any body need a anchor for a very small boat? For those who have actually done it will a new barrel with the M4 feed ramp extension function properly with an old school rifle-type upper receiver? Should not be too hard. I didn't forsee that we'd ever see the day when replacement parts would be so hard to get. Seems like it should work to me, but be a real challenge to keep clean and be damned ugly to boot. Looking for a black stripped A1 upper with non m4 feed ramps (just realized the upper I have wont work with my barrel). It gives a longer ramp that is less steep into the chamber. If you want precision, dont look to the mil-spec gun, look to the one that is popular in 3-gun competitions, at Thunder Ranch, etc. AR9 - Help diagnosing feeding issue. Bullets tend to bump, snag, and stub on these guns. If it's happening regularly, check the magazines you are using for serviceability. This USGI modification was done to both the barrel extension and the upper receiver, creating a longer and steeper feed ramp. 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. Not saying a really good gunsmith cant do it, just that theres a bit of an involved process. The dimensions are different between the two, so theyd have to change some things to the feed ramps dimensions. 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. Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. I like all my guns to be reliable. You can modify the upper, but bear in mind that the un-anodized aluminum surface will be very soft and prone to wear if your particular bullet hits it frequently. You wrote that much to make a point that should have taken about 100 words? The M4 Style Feed ramps And Barrel Extension Provide Consistent Feeding And The Matte Black Manganese Phosphate Finish resists External Corrosion And OxidationLength: 14.70"Model: AR-15Finish: Manganese PhosphateBarrel Type: Carbine LengthBarrel Features: Chrome-LinedManufacturer: FN Mfg Number: 20-100405Model: AR-15 . EDIT: Okay, I understand now! Is one better than the other? Our 6.5 Grendel Black Nitride rifle barrels are made from the finest 4150 Chrome Moly Vanadium and precisely rifled for high accuracy at a great price. My factory JP CTR-02 has the appearance of the bottom right picture in the post above, M4 barrel extension in a rifle receiver, and there is not a mark on the aluminum under the barrel extension. Load a magazine with two or three rounds, lock the bolt group back on your rifle or carbine and insert the magazine. Thats an important thing since without the feed ramps, issues can arise when receivers and barrel extensions are mismatched. They offer a lower, more extensive, and smoother entry for any round of ammo, whether its necessary or not. Inadequate knowledge about these feed ramps can lead to lots of problems with barrels because they are essential parts to guide the bullet up and into the chamber. By rejecting non-essential cookies, Reddit may still use certain cookies to ensure the proper functionality of our platform. AAC and anybody else that has any reasonable expectation of quality and reliability use an M4 feed ramp. I read in Bravo company that there are 2 kinds of flat top upper. I should have taken my own advice for once. Whether they materialize or not depends on the direction of the mismatch. It's near impossible to replace the carry handle upper I have these days, and finding a colt chrome lined 20" light weight barrel isn't a walk in the park either. Some barrels I see for sale say they include M4 feed ramps, and some uppers say they include them too. Change the angle so that the ramp ends at the exact same point. Notify me of follow-up comments by email. I recommend putting any AR-platform firearm together with a matched M4 barrel extension and upper receiver set, just because you can. I can probably get the upper reciever first. Its a miracle! FFL Fax: 866-721-8691. However, they do have M4 feed-ramps which is not clone correct. 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. Create an account to follow your favorite communities and start taking part in conversations. Backing up a ton: The ramps on regular barrel extension are cut just to the edges, while the M4 feed ramps have deeper cuts in the M4-spec upper receiver. colt A1E1 733 uppers didn't have extended carbine feedramps ? No need to alter the upper. 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. which is basicallly an m16a1 cut down. Sent back again. Description. 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. I will attest that a rifle upper and a barrel with the M4 feedramps works just fine. That is what I tell people when they try to convince me that they need a stainless barrel instead of chrome-moly. JavaScript is disabled. 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. If you have a bolt that you would like to use you are welcome to ship it to us for accurate headspace. upper recievers and barrels are hard to comeby. Here you can see an upper with "rifle" feedramps. BUT if you find someone to grind your feed ramps and they do a good job, post it up and let us know. Everything that you have on your side to make any weapons more reliable and work when it absolutely needs to is a plus. The M-16/M4 are great weapons. M4 barrel to non M4 receiver is fine, but not the other way around. There is a picture of the various options, hopefully another poster can link them. With the increased use of larger-diameter cased cartridges, the M4 feed ramps are proving their values when using them in those cartridges. 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.) . For new construction barrels only. You must log in or register to reply here. practical_man There are now thousands of upper receivers and ready-to-use barrels that have the cuts of M4 feed ramps. After two months of back and forth, cleaned up the feed ramps.