View Full Version : Colt AR15A4 front sight base and receiver markings
Would I be correct to assume that the AR15a4s were all supposed to have F-marked FSBs after around 2015? And what receivers have they been using. I just got mine today from Brownells and it has a NON-marked FSB and a receiver that says "AR15A4 Lightweight LE Carbine". I'm just curious.
Which model did you buy, the 20" AR15A4 with the fixed a2 stock, or the 16" 6720 with collapsible stock because my 6720 has a .625" diameter (for the lightweight barrel) non f marked front sight post and is rollmarked AR15A4 lightweight LE carbine. My AR15A4 20" government model bought last fall has a f marked sight and is rollmarked just AR15A4.
Which model did you buy, the 20" AR15A4 with the fixed a2 stock, or the 16" 6720 with collapsible stock because my 6720 has a .625" diameter (for the lightweight barrel) non f marked front sight post and is rollmarked AR15A4 lightweight LE carbine. My AR15A4 20" government model bought last fall has a f marked sight and is rollmarked just AR15A4.
It's the full 20" AR15A4 rifle. I noticed that earlier 20" sometimes had the 6720 lower receiver, but supposedly all of that has been fixed. It's a 5 digit serial, but I need to look up the barrel date and see.
EDIT: I pulled the handguards off and the barrel is dated June 2017... apparently Colt is back to using non f-marked FSBs probably to keep up with demand.
Mrgunsngear
08-17-17, 19:17
Would I be correct to assume that the AR15a4s were all supposed to have F-marked FSBs after around 2015? And what receivers have they been using. I just got mine today from Brownells and it has a NON-marked FSB and a receiver that says "AR15A4 Lightweight LE Carbine". I'm just curious.
I just got another from Brownells and it has a non C marked carrier as well. I realize this has been discussed at length but just adding another data point.
I just got another from Brownells and it has a non C marked carrier as well. I realize this has been discussed at length but just adding another data point.
Yeah, I just noticed that while doing the deep clean. I didn't know if there was a discussion on the recent ar15a4s that had come out. I had not found many recent threads on it. I just found a member on another board that got a rifle exactly like mine three weeks ago from another retailer. Colt stated that the receiver and fsb were confirmed mistakes and took his rifle to give a replacement within two months.
The wait time isn't worth it to me. I can always replace the fsb and my paperwork matches the receiver serial, so I'll have prove it isn't a pieced together rifle.
Good luck with the FSB replacement.
Yeah, I just noticed that while doing the deep clean. I didn't know if there was a discussion on the recent ar15a4s that had come out. I had not found many recent threads on it. I just found a member on another board that got a rifle exactly like mine three weeks ago from another retailer. Colt stated that the receiver and fsb were confirmed mistakes and took his rifle to give a replacement within two months.
The wait time isn't worth it to me. I can always replace the fsb and my paperwork matches the receiver serial, so I'll have prove it isn't a pieced together rifle.
Good luck with the FSB replacement.
Haha. Is it as bad as removing a BCM one? I've done both (off a 6920 and a BCM LW barrel) before during an armorer course and in my free time.
Like I said, it's not a big deal to me. I was just curious if others with recently built rifles are seeing the same. I'll play with the idea of calling colt.
Removal isn't hard with the right tools. It's trying to install one on a barrel where an FSB was already in place.
Haha. Is it as bad as removing a BCM one? I've done both (off a 6920 and a BCM LW barrel) before during an armorer course and in my free time.
Like I said, it's not a big deal to me. I was just curious if others with recently built rifles are seeing the same. I'll play with the idea of calling colt.
Ah, that is true.
Removal isn't hard with the right tools. It's trying to install one on a barrel where an FSB was already in place.
Talked to Colt about this. Latest batch has unmarked carrier and non F-marked FSB. It's not an issue.
Colt uses whatever parts they have lying around. No big deal. if you can zero it, then here is no issue!
Colt uses whatever parts they have lying around. No big deal. if you can zero it, then here is no issue!
Agreed. I was just curious if that was how they are shipping. I'm guessing the spare parts are from 6720s given the FSB and receiver.
Ah, that is true.
Your new FSB will not be drilled and reamed and a used one that has been drilled will not fit the holes in your barrel. For practical purposes your FSB is part of the barrel.
Your new FSB will not be drilled and reamed and a used one that has been drilled will not fit the holes in your barrel. For practical purposes your FSB is part of the barrel.
Yeah, I forgot about all that until IG brought it up. I've pulled and placed them back on to replace end caps and such but never put a brand new one on a barrel.
Colt uses whatever parts they have lying around. No big deal. if you can zero it, then here is no issue!
While I want to agree that a non-F FSB is much ado about nothing, SMEs have frequently stated otherwise. Even quite recently (https://www.m4carbine.net/showthread.php?188626-Need-some-help-on-BCM-markings&p=2381825#post2381825)...
Not really, just garbage. Incorrect FSB, shit barrels, out of spec chambers, etc...
The FSB issue is real. Go ask guys who do training to include PD's who have guys that have issues getting weapons zeroed.
Although, it wasn't brought up this time around. Can't imagine why. Maybe something's changed.
Basically I quit bashing every dead horse that's been bashed. Considering there are multiple front sight posts, etc.. if stuff isn't right it's an issue. I've had numerous LE agencies concur the same issues in my courses.
While I want to agree that a non-F FSB is much ado about nothing, SMEs have frequently stated otherwise. Even quite recently (https://www.m4carbine.net/showthread.php?188626-Need-some-help-on-BCM-markings&p=2381825#post2381825)...
Although, it wasn't brought up this time around. Can't imagine why. Maybe something's changed.
While I want to agree that a non-F FSB is much ado about nothing, SMEs have frequently stated otherwise. Even quite recently (https://www.m4carbine.net/showthread.php?188626-Need-some-help-on-BCM-markings&p=2381825#post2381825)...
Although, it wasn't brought up this time around. Can't imagine why. Maybe something's changed.
Flat top uppers zero fine with A2 FSBs.
Have you had a different experience?
New incoming member Alex112358 sent this to me via PM. He contacted Colt via Facebook regarding the issue. He also got his through Brownell's. Here is the message:
Alex
Hi. Recently purchased a new 20" AR15A4.
The lower receiver is marked "Lightweight LE Carbine" Just curious as to why on this 20" rifle? The fsb, bcg, and buffer are all unmarked as well. Are they the same as the marked parts? Thanks
Colt
Colt That marking is an anomaly. Regarding the other components - the FSB and buffer don't currently feature any marking, and there was a batch of factory BCG's to leave here without the expected marking recently, but they are the real thing.
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I'd be curious to measure these FSBs to see if maybe they just didn't get marked, but are "F-marked" fsbs.
Flat top uppers zero fine with A2 FSBs.
Have you had a different experience?
Personally. No, I have not.
Just think it's funny that FSB hysterics seem to be solely dependent upon roll marks.
The wait time isn't worth it to me. I can always replace the fsb and my paperwork matches the receiver serial, so I'll have prove it isn't a pieced together rifle.
Wrong
Colt frequently does not use F marked front sight bases on commercial flattop 20" rifles. Several 6700 HBARs are also built this way. This has been going on since 1994.
You cannot replace a FSB with another one. The holes not interchangeable. You will ruin the value of your barrel if you remove the FSB. The average person does not have the tools to remove it successfully.
No, the shitty orange hockey puck thing sold by Brownells doesn't not work and neither does any other jig or fixture offered to consumers.
I appreciate the replies, guys. Even the "wrong" above. We've already ascertained this and have since moved on. To some people, it matters, hence my question. People sure do get testy over this, eh?
Colt frequently does not use F marked front sight bases on commercial flattop 20" rifles. Several 6700 HBARs are also built this way. This has been going on since 1994.
You cannot replace a FSB with another one. The holes not interchangeable. You will ruin the value of your barrel if you remove the FSB. The average person does not have the tools to remove it successfully.
No, the shitty orange hockey puck thing sold by Brownells doesn't not work and neither does any other jig or fixture offered to consumers.
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