To Grind or Not To Grind ???

[mildcustom2]

So your assembling your AR and notice your upper receiver has M4 feed ramps but the barrel has standard rifle feed ramps on the barrel extension. Do you.....

A) Whip out the Dremel tool and start making those suckers conform on the barrel extension.

B) leave it, try it, praying you don't have a failure to feed.

C) Give up and buy a new barrel.

D) take it to a gunsmith and pray they can install a new barrel extension without screwing up your barrel.

E) Buy a new upper receiver without the M4 feed ramps.



A pic for reference as to what I'm talking about. It's the bottom left image in the pic, M4 Receiver with rifle extension.

 

[Ar180shooter]

D or E. I would not dremel it. A gunsmith may also be able to cut the rifle feed ramps to M4 feed ramp specs.

On that note, I'm looking for a stripped AR upper.

 

[mwjones]

I don't see why you couldn't do that yourself with a fine round file. The other options listed are to get a new one, which costs money, take ti to someone, which costs money, so if you bugger it, you were going to buy another one anyway or spend a bunch of money having it done. Not much to lose there.

 

[RUSTSPOT]

friend done it with gremel and it looked nice and polished up. perfectly smooth feed ram from receiver to barrel extension

 

[09outlander]

If you do your self use a round file as was stated by mwjones, I wouldn't use a dremel, it would be to easy to remove to much material. Slow and steady is the way to do this.

Andrew.

 

[Striker66]

A) Whip out the Dremel tool and start making those suckers conform on the barrel extension.

I'd say this is your best scenario if you're confident with the dremel, or get a gun plumber to do it. A file more then likely won't cut
very well since the extensions are case hardened 8620 steel.

D) take it to a gunsmith and pray they can install a new barrel extension without screwing up your barrel.

IMO Not at all likely a new extension would orient correctly relative to the gas port. Even if one is close then you're either shimming it to
orient properly (increasing head space, potentially dangerous) or facing material off of the shoulder and end of barrel (reducing head space and needing a clean up with a chambering reamer- assuming it isn't chrome lined or melonited, but also changing the relationship of the gas port/tube to the rest of the gun)

E) Buy a new upper receiver without the M4 feed ramps.

Another albeit "ghetto" solution would be to coat the barrel extension with release agent and fill the gap with Devcon or something
similar so the tip of a cartridge wouldn't be able to get trapped there.

 

[ted_dent]

Dremel, NO! Things can go too wrong too fast. Go slow and steady with the proper diameter round file and it's a pretty simple job. You could use the Dremel to polish the blended ramp/extension with a fine Cratex tip but that's the only place I would use a Dremel for a job like this. Or I'll sell you a proper M4 barrel extension for $25.

 

[8 ball]

Personally, I'd take the Dremel to it. Go slow and take it cool and I know I could do a good job of it. YMMV!

 

[metcalfe]

Take it to a trusted gunsmith or sell the barrel and get another with m4 feed ramps.
Don't dremel it!

You're building a sub moa ar, right?
Tolerances matter.
Don't dremel it!

You're not a gunsmith
Don't dremel it!

 

[mildcustom2]

Alright so this was more a question on what you would do when encountering what is a very common problem when people go to install a rifle length barrel into a upper receiver with M4 feed ramps. All rifle length barrels come with standard barrel extensions installed unless you specifically order, pay and wait to get one with an M4 barrel extension. There are only two correct answers here and I will break it down.

Option:

A. Break out the Dremel tool and grind away making the feed ramps conform is the only way to fix a barrel with a standard barrel extension installed and is very common. You are removing very little material so its a task that takes a matter of minutes. You can not use a file to do it as the hardened steel will eat up your file before you even put a scratch in the barrel extension, must be done with a fine grinding stone slowly. Sending it to a gunsmith and having them do it means they will do the exact same thing with a grinding stone. How do you think they polish feed ramps? It's all done by hand.

B. can't leave it, while in some very rare cases it does not cause a feeding issue, most of the times it does. The tip of the projectile or rim of the case will catch on the edge protruding over the feed ramp causing a jam. So it must be modified.

C. Sure buying a new barrel with a M4 extension is an option but a very costly one impractical one. Plus you will have to wait 5-6 months for a new barrel. Waste of time and money for such a simple problem.

D. Installing a new barrel extension is a definite problem and disaster. Barrel extensions are drilled and pinned in one shot, trying to install a new barrel extension will the majority of the time end up with a alignment issue or head spacing issue, typically an alignment issue though.

E. buying a upper receiver without M4 feed ramp cuts is an option, costs a couple bucks but not a big deal. The problem is that many many manufactures these days are manufacturing there upper receivers with M4 feed ramps as its the latest hype. M4 feed ramps were started by Colt, They figured the extended ramps " would " increase the reliability of the rifle and prevent failure to feed. M4 feed ramp design and concept is or was patented by Colt however many others use this style in there Rifles.




Soooooooo if anyone else has anything to add or if I've left something out please feel free to comment.

 

[cn_1]

Alright so this was more a question on what you would do when encountering what is a very common problem when people go to install a rifle length barrel into a upper receiver with M4 feed ramps. All rifle length barrels come with standard barrel extensions installed unless you specifically order, pay and wait to get one with an M4 barrel extension. There are only two correct answers here and I will break it down.

Option:

A. Break out the Dremel tool and grind away making the feed ramps conform is the only way to fix a barrel with a standard barrel extension installed and is very common. You are removing very little material so its a task that takes a matter of minutes. You can not use a file to do it as the hardened steel will eat up your file before you even put a scratch in the barrel extension, must be done with a fine grinding stone slowly. Sending it to a gunsmith and having them do it means they will do the exact same thing with a grinding stone. How do you think they polish feed ramps? It's all done by hand.

B. can't leave it, while in some very rare cases it does not cause a feeding issue, most of the times it does. The tip of the projectile or rim of the case will catch on the edge protruding over the feed ramp causing a jam. So it must be modified.

C. Sure buying a new barrel with a M4 extension is an option but a very costly one impractical one. Plus you will have to wait 5-6 months for a new barrel. Waste of time and money for such a simple problem.

D. Installing a new barrel extension is a definite problem and disaster. Barrel extensions are drilled and pinned in one shot, trying to install a new barrel extension will the majority of the time end up with a alignment issue or head spacing issue, typically an alignment issue though.

E. buying a upper receiver without M4 feed ramp cuts is an option, costs a couple bucks but not a big deal. The problem is that many many manufactures these days are manufacturing there upper receivers with M4 feed ramps as its the latest hype. M4 feed ramps were started by Colt in an attempt to get a patent through on the M4 platform. They figured the extended ramps " would " increase the reliability of the rifle and prevent failure to feed.




Soooooooo if anyone else has anything to add or if I've left something out please feel free to comment.

Completely untrue. They were a necessary addition to prevent failures to feed, not to get a patent through or start a hype. And not all rifle length barrels come with standard barrel extensions.

 

[mildcustom2]

Completely untrue. They were a necessary addition to prevent failures to feed, not to get a patent through or start a hype. And not all rifle length barrels come with standard barrel extensions.

The debate over wether or not M4 feed ramps has anything to do with reliability is a debate that's been going on for a very long time and not one I am interested in getting into. The concept and design was or still is patented by Colt and the design was incorporated into the original M4 rifle they presented to the US Department of Defense when they were looking for a replacement for the M16.

As for wether rifle length barrels have standard or M4 barrel extensions, let me clarify. A majority of off the shelf barrels including Kreiger, Rock River Arms etc etc utilizing the rifle length gas system has standard barrel extensions installed unless ordered with an M4 barrel extension.

 

[cn_1]

The debate over wether or not M4 feed ramps has anything to do with reliability is a debate that's been going on for a very long time and not one I am interested in getting into. The concept and design was or still is patented by Colt and the design was incorporated into the original M4 rifle they presented to the US Department of Defense when they were looking for a replacement for the M16.

As for wether rifle length barrels have standard or M4 barrel extensions, let me clarify. A majority of off the shelf barrels including Kreiger, Rock River Arms etc etc utilizing the rifle length gas system has standard barrel extensions installed unless ordered with an M4 barrel extension.

M4 feed ramps can help reliability under certain conditions. There's really nothing to debate about that...

 

[mildcustom2]

M4 feed ramps can help reliability under certain conditions. There's really nothing to debate about that...

Ok then prove it and explain to me why companies with Defense and Law Enforcemet contracts like Stag Arms include it in some receivers and not others.

 

[09outlander]

Ok then prove it and explain to me why companies with Defense and Law Enforcemet contracts like Stag Arms include it in some receivers and not others.

I don't think M4 feed ramps do anything for a semi auto rifle, I think and I may be wrong, but there usefulness is for full auto.

 

[mildcustom2]

I don't think M4 feed ramps do anything for a semi auto rifle, I think and I may be wrong, but there usefulness is for full auto.

You are 100% correct. This is when M4 feed ramps are useful and why Colt put them on there first M4 they presented to the US department of Defense when they were looking to replace the M16.

But this is why I was saying its a huge debate on AR15 forums as to wether they increase reliability given a majority of the AR's in civilian hands in North America can't go full auto. And this is why many rifle length barrels don't have M4 barrel extensions unless ordered that way. Precision AR15's for matches don't need them because they will never go full auto.