Comparison Chart of Major AR Brands

**C4IGrant** · 08-07-07, 14:20

Originally Posted by AR15barrels

I put together a 14.5" LMT upper this evening dated 6-7-07 on the QC tag.
It has straight pins.

Please post a photo of these taper pinned LMT barrels.
I don't believe it without seeing it.

Got one better than that. Just built a 16" upper with the date on the QC tag reading 07-19-07

C4

**dangertree** · 08-07-07, 14:48

Originally Posted by rob_s

Keep in mind, RRA is famous for simply dremmeling-in "feedramps" after the complete rifle is assembled.

We've had a few Colt LE6520s come through the shop in the last year with receiver ramps cut post anodizing. I really haven't examined many RRAs up here, so I can't comment on what they do.

Good job with the chart referencing who does what. Flow of info is always good.

For my personal use, on semi-auto guns, I'll admit I'm not particularly concerned with the type of feed ramp on the gun, as long as it is correct (ie: no M4 receiver with rifle barrel extension). The newer CF C8 carbines apparently run with M4 type barrel extensions in A4 type uppers, I've not heard of feed issues. Some of our rifles (Stag/CMT mainly, disclaimer, which we sell) have M4 extensions/M4 uppers, most have rifle ramps/A4 uppers.

I see reference to hollowpoint ammo issues, I don't have personal experience with problems feeding HP that I could trace to extended ramps preventing (ie, misfeeds impacting the front of the mag, rather than the receiver below the barrel extension), but I sincerely take peoples word on it, particularly so with longer heavy bullets. However, 97% of what I shoot is 62gn ball ammo, with a bit of 68gn BTHP.

I understand the reasons issued for the use of M4 ramps, particularly with full auto, and certainly don't object to them or anything (!), just not something I've had cause to think about. I request M4 ramps/uppers on full auto carbines and custom orders.

On the Colts I referenced above, properly done, the bevel in the receiver is not much aluminum to displace, I reckon they're working fine.

All the best.

Walt

**rob_s** · 08-07-07, 14:54

Colt 6520s have come with the ramps after-machined for at least two years as I have two that are that old. I don't mind their version as much because they are actually using an M4 barrel extension and are doing a damn good job of machining the ramps into the receiver.

The RRA attempts that I've seen have been rather abysmal. Basically they've just scratched off the anodizing and not much more. Hopefully the forthcoming pics will shed some light on this.

**AR15barrels** · 08-07-07, 14:58

Originally Posted by rob_s

The RRA attempts that I've seen have been rather abysmal. Basically they've just scratched off the anodizing and not much more. Hopefully the forthcoming pics will shed some light on this.

Recent RRA uppers have shown actual MACHINED (like with an endmill) feedramps.
MUCH better than the dremel jobs we are used to seeing.

**C4IGrant** · 08-07-07, 15:13

Originally Posted by dangertree

We've had a few Colt LE6520s come through the shop in the last year with receiver ramps cut post anodizing. I really haven't examined many RRAs up here, so I can't comment on what they do.

Good job with the chart referencing who does what. Flow of info is always good.

For my personal use, on semi-auto guns, I'll admit I'm not particularly concerned with the type of feed ramp on the gun, as long as it is correct (ie: no M4 receiver with rifle barrel extension). The newer CF C8 carbines apparently run with M4 type barrel extensions in A4 type uppers, I've not heard of feed issues. Some of our rifles (Stag/CMT mainly, disclaimer, which we sell) have M4 extensions/M4 uppers, most have rifle ramps/A4 uppers.

I see reference to hollowpoint ammo issues, I don't have personal experience with problems feeding HP that I could trace to extended ramps preventing (ie, misfeeds impacting the front of the mag, rather than the receiver below the barrel extension), but I sincerely take peoples word on it, particularly so with longer heavy bullets. However, 97% of what I shoot is 62gn ball ammo, with a bit of 68gn BTHP.

I understand the reasons issued for the use of M4 ramps, particularly with full auto, and certainly don't object to them or anything (!), just not something I've had cause to think about. I request M4 ramps/uppers on full auto carbines and custom orders.

On the Colts I referenced above, properly done, the bevel in the receiver is not much aluminum to displace, I reckon they're working fine.

All the best.

Walt

On the 6520's, Colt is using M4 barrel extension (not rifle) and then machining the M4 cuts into the receiver (not some guy with a dremel tool).

Only a small run of Stag/CMT AR's have ever had M4 barrel extensions and M4 upper receivers. All non special ordered Stag's come with rifle barrel extensions and A3 receivers.

C4

**Pat_Rogers** · 08-07-07, 15:14

Caveat- i am not a mchinist, gunsmith or armorer.

I truly love coming here for the amount of qulaity information being passed.
One doesn't have to agree with everything of course, but when people who actually do this for a living can share information like that above, good things happen.

Nice work guys!

**C4IGrant** · 08-07-07, 15:14

Originally Posted by AR15barrels

Recent RRA uppers have shown actual MACHINED (like with an endmill) feedramps.
MUCH better than the dremel jobs we are used to seeing.

Haven't seen any of these, will be on the lookout for them.

C4

**C4IGrant** · 08-07-07, 15:15

Originally Posted by rob_s

Colt 6520s have come with the ramps after-machined for at least two years as I have two that are that old. I don't mind their version as much because they are actually using an M4 barrel extension and are doing a damn good job of machining the ramps into the receiver.

The RRA attempts that I've seen have been rather abysmal. Basically they've just scratched off the anodizing and not much more. Hopefully the forthcoming pics will shed some light on this.

Like this?

C4