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Tonester2

Replace stock gas block with iron sight

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My Bushmaster Varminter doesn't have a front sight nor any rails on the hand guard for me to mount one but I want a set of iron sights. So I'm looking to replace the stock gas block with one that has an iron sight build in along with a sling loop. It has a .750" barrel. Is this what I need? I understand I'll need to get a rear sight as well but that's easy because there's is a Picatinny rail back there.

https://www.opticsplanet.com/cmmg-inc-f-marked-tri-frt-sight-base-ass.html

Thanks

opplanet-cmmg-inc-f-marked-tri-frt-sight-base-ass-55da338-main.jpg

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6 hours ago, Tonester2 said:

My Bushmaster Varminter doesn't have a front sight nor any rails on the hand guard for me to mount one but I want a set of iron sights. So I'm looking to replace the stock gas block with one that has an iron sight build in along with a sling loop. It has a .750" barrel. Is this what I need? I understand I'll need to get a rear sight as well but that's easy because there's is a Picatinny rail back there.

https://www.opticsplanet.com/cmmg-inc-f-marked-tri-frt-sight-base-ass.html

Thanks

opplanet-cmmg-inc-f-marked-tri-frt-sight-base-ass-55da338-main.jpg

You're going to have to drill this front sight for the taper pins, and you better hope they line up with the original cuts already in the barrel AND it looks a true 90 degrees. 

 

Order the JP front sight instead. The set screws usually align with the taper pin holes on the underside of the barrel. 

 

 

 

 

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12 minutes ago, Parker said:

You're going to have to drill this front sight for the taper pins, and you better hope they line up with the original cuts already in the barrel AND it looks a true 90 degrees. 

 

Order the JP front sight instead. The set screws usually align with the taper pin holes on the underside of the barrel. 

 

 

 

 

Cool. Got a link?

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1 hour ago, High Exposure said:

Does that hand guard use a standard barrel nut?

I recommend changing the hand guards out to something that uses the same barrel nut, that has a free-float tube and a rail at 12 o’clock, then put a folding BUIS up front.

Messing with gas blocks is always my last resort. 

Unfortunately the hard guard doesn't use a standard barrel nut with a spring. I thought about replacing the guard with one that has the rails but I can't get the stock guard off. I'm still contemplating on what to do and explore my options. Maybe I'll just get a red dot or scope and be done with it.

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The barrel nut doesn’t have a spring and ring. That an add on to the barrel nut on a mil-spec carbine.

That gun is made for optics - specifically magnified scope. You’re trying to put lipstick on a pig and ultimately, the juice is not going to be worth the squeeze. 

I agree with @silverado427’s recommendation - buy a complete 16” upper. I recently saw Colt 16” 6920 complete uppers (includes BCG and CH) for sale for around $500 - can’t remember if it was Aim Surplus or Arms Unlimited….

Look around, deals are out there.

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I would change the upper. In the long run you’ll be better off. While a good AR gunsmith can fit a new gas block to your upper using the original taper pin holes, it won’t be cheap. Combine that with the cost of the gas block, etc, you’re better off buying a new upper. 
 

I think High Exposure was referring to Arms Unlimited for the Colt 6920 upper. 
 

 

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Between existing muzzle devices that are pinned and/or welded, and having to clock it and drill the barrel for a taper pin, the easiest route to a set of iron sights is to replace the forearm with something with a rail. At least without buying a new upper. 

 

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3 minutes ago, raz-0 said:

Between existing muzzle devices that are pinned and/or welded, and having to clock it and drill the barrel for a taper pin, the easiest route to a set of iron sights is to replace the forearm with something with a rail. At least without buying a new upper. 

 

That was my initial recommendation as well. However, that solution only works if you can find a tube that fits on the existing barrel nut. You can’t swap the barrel nut without first removing the gas block. You can’t remove the gas block without removing the muzzle device… it’s a vicious cycle.

I am not sure how proprietary the barrel nut on that model of rifle is.

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6 minutes ago, High Exposure said:

That was my initial recommendation as well. However, that solution only works if you can find a tube that fits on the existing barrel nut. You can’t swap the barrel nut without first removing the gas block. You can’t remove the gas block without removing the muzzle device… it’s a vicious cycle.

I am not sure how proprietary the barrel nut on that model of rifle is.

Stock barrel nut fits over a lot of gas blocks. But there's a fair variety of forends that clamp onto the mil-spec nut. THere's always rails that mount to the pic rail on top too. They are heavy and suck, but it's a varminter.... weight is good right? 

But unless it is something weird, the bushmaster varminter gas block is like a cut down minimalist version of the a2 front sight. It also has no muzzle device. SO they may be able to bash out the taper pins and put an a-2 on it. but if they don't want that the barrel nut should clear the block if you wiggle it right IIRC. 

 

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