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AR-10/LR308 Gunsmithing?


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Folks, I need two front sight bases installed and need some good guidance/recommendations.  The first barrel is a 20" Rainier AR-10 format barrel that will get a standard A2 FSB, the other is an 18" Black Hole Weaponry DPMS format unit that will get an "F" marked FSB.  Both barrels and both FSB's are .750".  Thanks in advance folks! <thumbsup>

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F marked front sight bases were developed by Colt, for the M4A1 Carbine sight radius. Carbine gas port location on a 14.5" 5.56 barrel.

 

You don't need the F marked front sight base on a rifle with an 18" barrel, considering it's probably not a carbine gas system, and it's not a 5.56 rifle.

Edited by 98Z5V
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You're absolutely correct.  However, I've been working on these two builds since the middle of 2013 and am trying to work with what I've got.  It took forever to get the barrels I needed so now I'm trying to get the FSBs mounted.  The A2 FSB is going on the 20" barrel on an older AR-10B with the carry handle charging handle.  The "F" marked FSB is going onto the 18" barrel (and yes it's a rifle length gas system) which will use a flat-top SI Defense receiver set.  I didn't think the F marked FSB would be that big a hindrance on the flat-top rifle.  If necessary I could always shorten the front sight post.  I thought the carry-handle AR-10 rig would be more critical and should get the A2 FSB.  I just need to find someone that can mount these and do the job properly.

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  https://www.adcofirearms.com/

   Even if your barrels have been set up for the Taper pins for an A2 front sight /gas block , if you are not using the one that was fitted to that particular barrel , might have fitment or gas port alignment problems. 

  Call or email ADCO & they will direct you as to what they or you can do . If using a clamp on or set screw type A2 type sight/gas block , installing will not be a problem & no need to send them off .

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http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1889888#post1889888

I've had issues with two uppers I had ADCO work on. On one the barrel was canted on the other the dd RIS II was not installed correctly. I was able to fix the ris ii myself by simply loosening the bolts and being more careful with the tightening order and torque. When I contacted ADCO, both times they responded to the effect "sorry but that happens sometimes." No offer on their part to make it right. Based on my experience, I would avoid ADCO, clearly not what they once were.

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1892151#post1892151

I had a gas block pinned by ADCO last year. This is how it played out:

After about 2 weeks, I contacted Adco to see if there were any problems. Steve contacted me and advised that my supplied gas block was undersized while my barrel was over-sized and that I would have to either get a new gas block or they could turn down the barrel. I elected for a new gas block. I told Steve, to use his best judgement so long as it is steel and is of good quality. After conveying this, I waited 2 more weeks before asking for another update. When Steve contacted me, he re-hashed the initial gas block/barrel issue, and I AGAIN repeated my instructions for him (still not sure where the disconnect was in that).

After 4 weeks, I got my upper back and upon final assembly, I noticed that the gas block is noticeably canted. On top of that, the gas block I had originally included was now missing its proprietary set screws, roll pin, and gas block pin. Again, I contacted Steve regarding these issues*. He advised it wasn't a big deal and that he would check with the shop about those parts. After nothing came from this, I reached out one more time...no response.

No really BIG problems here, but all those little things added up and my rather mediocre experiences prior to this, I don't have the confidence to use them for any future projects/services.

*to be fair, some of the issues encountered with this barrel might be on the manufacturer and not ADCO

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1892378#post1892378

I've used both and will only be using and recommending Rainier from now on.

ADCO gets a lot of love on the forums but my experiences with them have been much less than stellar, barrel not threaded right after a cut down and gas block came back pinned on backwards . To ADCO's credit they came up with acceptable fixes for both but they shouldn't have happened in the first place.

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1892435#post1892435

I have had both work on my current AR. ADCO screwed up the upper build and put a gas block on the barrel that wasn't small enough to free float the barrel. The gas block physically touched the RISII system and you could move the barrel up and down inside the RISII by hand and it would stay in the position that you left it.

They did offer to take the weapon back and check it out, but instead of taking them up on it I had the guys at Rainier fix the weapon up. I have never had a bad experience with Rainier.

Rick

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1892781#post1892781

I bought an ADCO custom cruiser barrel from ADCO... way back during an earlier panic buying frenzy. It's essentially a 16 inch middy with a fixed FSB in the rifle position... kind of like a KINO upper, dig?

And althouth the barrel and final assembly are functional... the work looks like a fukking high school kid's shop project. They used a grinded down FSB for a lo pro gas block, and the pin job is nasty... using ONE roll pin through one of the FSB loops. Truly looks like a home job to save money.

I would NOT have them work on a gun for me.

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1893369#post1893369

Rainier Arms is top notch. I use them all the time. Great prices and great people. Years ago I had work done at ADCO and it was mediocre at best. I also had a friend that sent them a upper to pin a FH on and they drilled all the way through the barrel.

I would go with Rainier Arms any day.

http://www.m4carbine.net/showthread.php?148573-ADCO-vs-Ranier&p=1894995#post1894995

Have seen three ADCO muzzle device pin jobs that looked as if they were welded by a 3rd grader.

And this is just from one thread...

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OK, so I went and read completely through that whole thread. No pictures, only one paste of an email that actually didn't say what the poster interpreted it as saying, and lots of hearsay across the board. It's gonna take more than that to change my mind. I hate to be contradictory, but I'd rather be that than a lemming. My $0.02 anyways....

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That's perfectly fine if your opinion of them doesn't change, however I think it's important that people know not all is rosy with them. I've been seeing instances (and some very well documented ones) of their shens (both in workmanship and poor attitude) for the past five years and don't have enough customer trust to send any dollars their way.

Edited by FaRKle!
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Unfortunately, or fortunately depending on your point of view, I've only heard of one instance (at AR15.com BTW) where someone wasn't happy with ADCO's work but ADCO took it back and made things right and quickly!  Looks like I found the recommendation that I was looking for.  Thanks folks, especially 98Z5V!  <thumbsup>

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Unfortunately, or fortunately depending on your point of view, I've only heard of one instance (at AR15.com BTW) where someone wasn't happy with ADCO's work but ADCO took it back and made things right and quickly! Looks like I found the recommendation that I was looking for. Thanks folks, especially 98Z5V! <thumbsup>

Let us know how it works out, your experience might help someone else that might be uncertain.

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Folks, I need two front sight bases installed and need some good guidance/recommendations.  The first barrel is a 20" Rainier AR-10 format barrel that will get a standard A2 FSB, the other is an 18" Black Hole Weaponry DPMS format unit that will get an "F" marked FSB.  Both barrels and both FSB's are .750".  Thanks in advance folks! <thumbsup>

 

If you have a drill press you could do this yourself with out too much trouble.

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If you have a drill press you could do this yourself with out too much trouble.

 

 

  Yes , with the proper tapered drill bit  or milling bit & make a jig for port/gas tube alignment . You could do it by eyeing it , but a jig makes things some much less trouble & to proper spec's. Also have to remember that a std A2 sight"s gas port may be made to sit away from the barrels shoulder for a hand guard cap to fit between the sight & barrels shoulder. .

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  Yes , with the proper tapered drill bit  or milling bit & make a jig for port/gas tube alignment . You could do it by eyeing it , but a jig makes things some much less trouble & to proper spec's. Also have to remember that a std A2 sight"s gas port may be made to sit away from the barrels shoulder for a hand guard cap to fit between the sight & barrels shoulder. .

 

Actually all you need is a square, feeler gauge, and $20 reamer. But when in doubt ship it out.

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