Please clear up this AR F-marked thing for me

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DirtyBrad

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Jun 13, 2005
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Location
Maryland
Hello,

Still new to the AR world and am in the process of building one up. I ordered an M4 flattop upper from CMMG. I ordered everything with the default options.

The one thing I didn't really understand was the "F-marked front sight". I didn't realize until a minute ago that this was actually a different size. My plan was to buy a detachable carry handle somewhere a little cheaper. Does it matter which handle I buy or will anything work? If it does matter, what am I looking for?

Can someone give me a quick lesson on the F-marked vs. regular sights or point me in the right direction?

Thanks very much. Sorry if this is a bonehead question.
 
Ha ha... another homey from MD. What area are you in?

The difference in f- front sites and the regular civilian height is minimal. All that it takes is a screw in replacement front site for the f-marked height. You can get them from bushmaster and I'm sure a bunch of other sites. Im almost certain that my Rock River guns have the civilian front sites and I have no problem with both my carry handle on the 5.56 and the larue tactical back up site on the 9mm.

I would imagine that you wouldnt have a problem with any A2 style carry handle because they have elevation adjustments. On back up site systems (like the flip ups), there may be more of an issue. Again, I havent noticed any, but on my 5.56 I have an A2 handle and the 9mm has an aimpoint cowitnessed with the larue. Im not exactly engaging tango's at 300 meters with the 9mm, though :D .

That said, I dont believe you will have a noticeable problem. For all you could ever want to know about AR's, go to http://www.ar15.com. They have helped me out on many of occasion.

Oh yeah, are you going the Hbar route to avoid the "assualt weapon" waiting period or do you already have the lower???
 
Welcome to the AR world and the money pit that it is.

You should be fine with any rear sight you purchase. The problem is when you replace an A1 or A2 upper with an A4 upper and don't change the front sight base (FSB). Bushmaster did not use F marked FSBs and chose instead to just use a taller front sight post on their flat top rifles (or so I hear). Hope that helps.
 
Eleven minutes for two replies at 3:00 in the morning? You guys are getting slow.

I'm around Rockville. I'm currently waiting on the lower. Got an RRA from Atlantic last week and am hoping to be cleared to pick it up on Saturday. I'm excited, but slightly dreading all the tightness issues I've read about with them fitting the upper.

I have the LPK and stock and just ordered the M4 upper from CMMG. I know what you mean about it being a money pit. I started off trying to build the cheapest reliable rifle possible, but have -- shockingly -- gone over budget a little. I opted for the CMMG after talking to a Marine friend who strongly suggested I get a chrome-lined bore and chamber. It was about a hundred bucks more than the Stag I was originally planning on getting. I also splurged on three C Products mags. Just barely kept everything under $900.

Do you mean if I get a complete rifle with an HBAR that there's no waiting period? What a wacky place this is.

I did a search and saw a couple of things on AR15.com, but still wasn't clear. While they're the AR experts, THR has them beat for speedy responses and I'm trying to get everything ordered tonight.

Thank you for the responses. Sounds so far like I'm in the clear on the sights. Keep 'em coming, though.
 
The Stag upper will have many of the same features as the CMMG upper including the chrome bore and chamber as well as F marked front sight base.
 
Victor,

Now you tell me. I looked around, but couldn't find any information about that and didn't see specs for it on their website. Well, the shipping was a bit cheaper and I got a good deal on the carry handle, so it wasn't too much worse.
 
I've pretty much decided on going with the Stag just because I promised myself when I started this that I would be doing it on a budget and not get sucked into extras.

Still, it's only like ten percent more for the upper, so I may still do it. What is that magnetic particle testing?
 
Victor, you are the man.

I'd been waffling on this all day (and driving all my friends crazy). Ten Percent has them fifty bucks cheaper than from Stag direct, which means it's the clear winner. I could maybe talk myself out of fifty bucks for the 1:7, but not $100.

I just placed the order and got the very last one. Should be here next week. Thanks again everyone for all of the fantastic help. I'll post pictures when I get it built up and will buy Victor a beer if we ever meet.
 
DirtyBrad, is there any particular reason you arent going the RRA upper route... the RRA upper would fit the lower like a glove and you would have a color matching rifle. I love my two built RRA guns.

How much exactly are you looking to spend on an upper??? Reason I ask is because you can get a RRA complete flattop chrome lined 16" M4 upper for around $450 shipped if you know where to look (Legal Transfers on AR15.com).

Oh yeah, if you would have bought the full rifle in the HBAR configuration, there would have been no waiting periods... it would have worked like any shotgun or hunting rifle. Apparently we can't be trusted with government profile barrels... the weight of the HBAR must make it less suitable for slaughtering young children or something...:banghead:
 
Whoops...

Didnt see your post when I made mine. I guess you got what you wanted and supported a fellow THR member in the process.:cool:

The wait is going to be the worst part of it all... I couldnt stand waiting for my upper. It seemed like forever.

Congrats man... but be warned that AR15's are a mans Coach Purse... gotta have one of every style, ya know.
 
Zero, if I cancel another order today, I'm going straight to hell.

I wasn't originally going to get the RRA lower. I had planned on buying a cheaper one from Del-Ton, but my FFL holder dropped off, so I checked local shops and found the RRA for what it would have cost for the DPMS plus the transfer fee.

I was going to get the cheaper Del-Ton upper, but then thought I'd spend a bit more on the nicer Stag, then got hung up on this chrome chamber thing.

I did look at the RRA uppers, but wasn't seeing quite what I wanted. I didn't see any M4 style barrels, I read that not all of their receivers are chrome-lined, and the wait was like 4 - 8 weeks.

That's fantastic about the HBAR. It almost seems like the laws make no practical sense at all. But that couldn't be the case...
 
Ha, and now I'm posting overtop of you. Yeah, I'm very satisfied with the Stag upper at $525 shipped. I think that I can finally settle and stop second-guessing myself. I remember after I bought my car and did all the research, I said I'm not going to look at any prices for them now that I've paid for mine.

Good analogy about the purses. I'll definitely be using that one on my girlfriend in the future. She has a purse that came with a keychain miniature version of itself.

I'm already thinking about how my next one will have a gas-piston system, or maybe a 20", or maybe OD furniture or...
 
On the subject of CMMG uppers, are their extended feed ramps actually M4 ramps, or are they just barely visible in the upper like RRAs?
 
The feed ramps on the Stag are the normal style. Not sure there is much advantage to having M4 ramps on a semi-auto. Anyone with more info on this?
 
I was just reading up on this on AR15.com. There are the usual "I have jams without them every third round"/"I've never had them, never had a jam"/"They're for mall ninjas like" responses.

It seems like they definitely don't hurt anything and that they sometimes help.

Oh, several people mentioned adding their own with a file or Dremel. Not sure how good of an idea that is.
 
The feed ramps on the Stag are the normal style. Not sure there is much advantage to having M4 ramps on a semi-auto. Anyone with more info on this?
Click to expand...

The feed ramps were originally introduced because the faster cyclic rate of the M4 carbine meant that the magazine didn't always push the round into the optimum position before the bolt came back and they would occasionally strike below the feed ramps (especially with suppressors increasing the back pressure).

I don't have the feed ramps on any of my semi-autos; but from what I've seen they do seem to offer a tiny bit more margin of error if you are using long OAL rounds and/or marginal magazines. You can also opt to use the heavy-duty magazine springs to get the rounds into place quicker.
 
Does this result in a signature failure? I mean, will I be able to tell that's what's happening so that I need to try heavier springs?
 
frontsightbase2sw8.jpg
 
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