AR 'low profile' uppers - where does the brass go?

[socalbeachbum]

smooth sided uppers with no forward assist, no dust door, and no brass deflector, where does the brass end up upon ejection?

DPMS makes one I'm considering:

http://www.midwayusa.com/product/13...w-profile-flat-top-matte?cm_vc=ProductFinding

I notice the deflector protrusion on my MP15 gets hit with the brass every shot.

 

[MachIVshooter]

It ends up in the 4 to 5 O'clock position. If you're right handed, no problem. If you're a Southpaw, get a LW upper from Anderson or Aero Precision that has a deflector.

 

[socalbeachbum]

thanks. and is it a bad deal to not have the M4 feed ramps?

I do see the slick sided uppers for 458 SOCOM with M4 ramps

 

[Arizona_Mike]

Rainier Arms also sells a no-FA upper as well that has a FA and dust cover.

Mike

 

[NWcityguy2]

I don't know much about 458 Socom, but for the AR15 in general, you need to match the feed ramps on the barrel to your upper. So if the barrel has M4 feed ramps, the upper should as well.

 

[Arizona_Mike]

My SDM-R build has a rifle receiver and the barrel has M4 feed ramps and it works just fine (the original SDM-R is rifle/rifle). The converse is a problem as bullet tips can get hung up at the end of the M4 receiver cut if there is no corresponsing deep barrel cut.

I disagree with the person that made this picture. I think Rifle/M4 is a little bit better than Rifle/Rifle. M4/Rifle is the combination to avoid.

Mike

 

[gotigers]

I have an Aero Precision slick side upper. M4 feed ramps and not one issue in 2000 rounds since last June. Ejects no different than any other upper.

 

[MachIVshooter]

I disagree with the person that made this picture. I think Rifle/M4 is a little bit better than Rifle/Rifle. M4/Rifle is the combination to avoid.

Whether you agree or not, the author was correct. A rifle extension with M4 cut receiver means the bullets feed up the M4 ramps and get caught under the rifle extension. Ergo, that combination is bad.

 

[Arizona_Mike]

Whether you agree or not, the author was correct. A rifle extension with M4 cut receiver means the bullets feed up the M4 ramps and get caught under the rifle extension. Ergo, that combination is bad.

We seem to be in "violent agreement". Reread what I wrote.

My difference of opinion is on the order of preference of the good combinations. As far as Receiver/Barrel Extension combinations, the author seems to thing that both rifle is as good as both M4 and that a rifle receiver with an M4 barrel extension is not as good. I would put both M4 as best and an M4 barrel extension with a rifle receiver as good as or possibly slightly better than rifle/rifle as it is a little more open.

I think all three of us agree that you should never use a M4 receiver with a Rifle barrel extension.

Mike

 

[MachIVshooter]

We seem to be in "violent agreement". Reread what I wrote.

I read it fine. You wrote rifle/M4, which indicates the 3rd image, labeled rifle extension/M4 receiver. If you were referring to the 4th image (M4/rifle), then yes, we are in agreement. Functionally, there would really be no difference between the rifle BE with rifle receiver and M4 BE with rifle receiver, except that some build up would develop in the cavities where the barrel extension cuts dip below the receiver edge.

 

[Arizona_Mike]

I read it fine. You wrote rifle/M4, which indicates the 3rd image, labeled rifle extension/M4 receiver. If you were referring to the 4th image (M4/rifle), then yes, we are in agreement. Functionally, there would really be no difference between the rifle BE with rifle receiver and M4 BE with rifle receiver, except that some build up would develop in the cavities where the barrel extension cuts dip below the receiver edge.

Here is what I wrote: "My SDM-R build has a rifle receiver and the barrel has M4 feed ramps and it works just fine (the original SDM-R is rifle/rifle). The converse is a problem as bullet tips can get hung up at the end of the M4 receiver cut if there is no corresponsing deep barrel cut."

Mike

 

[Jeff White]

I wouldn't worry about the M4 or no M4 receiver cuts in a semi auto. One thing I would never do is have any type of AR without a dust cover. It doesn't weigh that much and you want to keep the crud out of the action.

 

[popper]

All my uppers are slick sided, 300BO had the extra stuff and dented the case mouth every shot. PITA if you reload. Changed to a slick side for the BO, solved problem. Don't take my rifles into the sand pile so no worry. Ejector spring usually puts them at 5 o'clock.

 

[Arizona_Mike]

I wouldn't worry about the M4 or no M4 receiver cuts in a semi auto. One thing I would never do is have any type of AR without a dust cover. It doesn't weigh that much and you want to keep the crud out of the action.

If you are worried about weight, you can get an aluminum dust cover door ($37) and rod ($8) from V7 weapon systems. I prefer no FA but always want a dust cover personally.

Mike

 

[chris in va]

One thing I would never do is have any type of AR without a dust cover. It doesn't weigh that much and you want to keep the crud out of the action.

What 'crud'? It's fully open after the first shot, unless you snap it closed every time you fire. No issues with my Sport's lack of dust cover. You get a lot of dust storms in Illinois?

 

[Jeff White]

Yes I do snap it closed after EVERY string of fire. It's a habit I picked up in a 28 year and 11 month career as an Army Infantryman.

If you run your AR wet dust, dirt and other crud WILL get into the the action if you run around with your dust cover open unless you shoot indoors all of the time.

I was issued my first M16A1 in December of 1974 and between then and when I retired in November 2003 I used them in every climate found on Earth from the temperate areas of CONUS to the arctic in Alaska, the jungles of Central America to the high desert.

During that time I think I have seen every kind of stoppage there is. Get enough crud blown into that open action and it will stop running.

Why do you think the dust cover was put there? Unlike the forward assist that was added as a solution to a non-existent problem, the dust cover serves a very useful purpose.

That's my personal experience with the weapon, obviously you don't use yours the way an Infantryman would. I doubt you spend a lot of time low crawling dragging your rifle through the dirt by the front sling swivel.

 

[kwg020]

I have the DPMS slick sided upper. I am not dragging my rifle through every mud hole and dust pocket on earth so I don't have foreign body stoppages with mine. I think it's got that "cool" factor. If you want a simple no frills rifle, you start with this upper.
kwg

 

[USAF_Vet]

It ends up in the 4 to 5 O'clock position. If you're right handed, no problem. If you're a Southpaw, get a LW upper from Anderson or Aero Precision that has a deflector.

I disagree. As a southpaw who has that exact upper on my rifle, I have had an altogether different experience with brass.

5.56 usually jumps out directly at 3 o'clock, .223 maybe a few degrees closer to 4.

I've never once been kissed by brass casings or steel.

I'll agree with the Aero or Anderson upper. The DPMS isn't bad, but at almost $90, you can do better with your money.

ETA: That actually isn't my upper. mine is a complete slab side, no shell deflector, and as a lefty I'm still not getting hit with spent cases.

 

[chris in va]

Deleted, not worth discussing.

 

[NWcityguy2]

Some people benefit from a dust cover, some people do not. There is no point in having a debate between the two groups.