View Full Version : Front Sight Base
Can someone school me on exactly how a standard front sight base is assembled onto a barrel?
I am assuming everything is put on a measured fixture, then drilled through one side of the Front sight Base through the bottom edge of the barrel and then through the other side of the Front sight base. Then the taper or straight pins are driven through locking it all in place solid as can be.
Am I close?
Thanks,
Jack
That's my understanding of it.
OK,
This is why I am asking. I have a guy that bought a bastardized AR. It looks like a nicely machined Front sight base where the sight tower part was cut away and it is used as a gas block. Now the crasy thing is that it has the normal handguard cab just behind the front sight base, and these funky handguards that go over and around the handguard cap.
He is having a hell of a time getting Iron sights that work in unison. I took a level to the upper and the rail section of the handguard at the front end, over the handguard cap, is lower than the height of the rail on the Upper Receiver.
My recommendation for him is to get a F marked front sight base, take off that shaved FRONT sight base, and replace it with a regular one. That way the BUIS on the upper receiver will be the correct height with the with the FSB.
Am I on the right track with this?
I saw BCM sells the FSB, but it would have to be drilled.
Does anyone offer a FSB? and Can I reuse the pins that are in there now?
Jack
At that point I'd anti-up for a Daniel Defense 9.0 rail and just mount the BUIS to it. That or ditch the upper on the internet and start from scratch.
There are some companies that will take a blank FSB and figure out a way to drill it to match your existing holes. Doesn't sound like this would be very cost effective in this case.
Go to this page (http://www.bushmaster.com/products.asp?cat=7) and scroll down to "disspipator". Is that what the FSB/gasblock looks like?
It actually looks like and probably is a Bush Master Optics READY Carbine....
JAck
Yeah, that's the same gas block as the Dissipator. Ugh.
Like I said, get the DD rail and install over it, or dump it and start over. There really isn't a cost-effective way to "fix" that.
I don't know if the DD Omega 9.0 would fit over it, but if it will that would be an option as well. You'd probably at least have to grind off the bayo lug and sling swivel. What a useless product that barrel/upper/gun is.
Does it have those stupid little risers on the upper? They come off, right?
http://www.bushmaster.com/images/catalog/xm_15_zoom/BCWVMF%2016M4ORC.jpg
Rob,
I bet it can be fixed... (does Randall Rausch post here anymore?)
It is a design that does not make sense to me. But then again this poor guy is trying to use this as a Defensive carbine now, I think he got taken, by a crafty salesman...
Jack
Rob,
I bet it can be fixed... (does Randall Rausch post here anymore?)
It is a design that does not make sense to me. But then again this poor guy is trying to use this as a Defensive carbine now, I think he got taken, by a crafty salesman...
Jack
Anything can be fixed, it's just a matter of how much it winds up costing. That's why I suggested just selling the upper and starting over. Unless he got a really fantastic deal on it or got really taken on it, I'd just prefer to start over. I don't now for sure how much the "repair" would cost.
Coincidentally, This is the same gay configuration of the carbines that we have. Ours have YHM aluminum BUIS front/ rear and are select-fire, 14.5 in. guns. The sights are terrible and are a PITA to deal with. I would say ditch the upper somewhere and get a good Noveske, LMT upper for it. If he was an armorer type then there would be more options available.
Yeah, that's the same gas block as the Dissipator. Ugh.
Like I said, get the DD rail and install over it, or dump it and start over. There really isn't a cost-effective way to "fix" that.
I don't know if the DD Omega 9.0 would fit over it, but if it will that would be an option as well. You'd probably at least have to grind off the bayo lug and sling swivel. What a useless product that barrel/upper/gun is.
Does it have those stupid little risers on the upper? They come off, right?
http://www.bushmaster.com/images/catalog/xm_15_zoom/BCWVMF%2016M4ORC.jpg
I would agree with Rob or Iraqgunz.
Ditch the upper first.
If that's not an option, ditch the rail and front sight he has now and go with a good rail that will fit over the gas block and either an LMT fixed rail mount front sight or a Troy folding rail mount front sight. I prefer fixed sights, and would personally go that direction.
Last option would be to send it to ADCO to have the gas block replaced with a standard F marked FSB. This service is listed on their website for $90. Of course their will be shipping either way, etc.
I have used ADCO a couple of times in the past and always had excellent service, a good price, and very quick turn around.
-RD62
Actually a pinned front sight base with the A frame removed makes a good low profile gas block. If it is the type pictured, just grind off the sling swivel tab and the bayonet lug, contour the bottom edges and paint it. Now install a free float rail and front sight and you are set. Or for a low cost solution get the Bushmaster modular accessory system sight that is designed to bolt on over the gas block (part #yhm-9360k).
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