M&P 15 Gas Block Question

Tom S. · #1 02-16-2023, 03:49 PM

A friend won a new MP-15 in an auction. He want to put an optic on it but it has that huge honking front sight/gas block sticking up in the way. He would like to retain a front swivel but many of the gas blocks I looked at don't seem to have them.

Can you guys recommend a replacement? It doesn't need to tacti-cool with 87 rails attached, just a replacement with a sling or sling attaching point.

Pisgah · #2 02-16-2023, 04:04 PM

If the optic is 3x or greater, he will never see the front sight. Otherwise, you could cut off the front sight or install a free-float fore-end with a low gas block.

Tom S. · #3 02-16-2023, 04:24 PM

Quote:

Originally Posted by Pisgah

If the optic is 3x or greater, he will never see the front sight. Otherwise, you could cut off the front sight or install a free-float for-end with a low gas block.

It's a non magnified red dot type sight. I figured changing the gas block would be the simplest/cheapest solution. Pretty sure he doesn't want me to cut off the front sight!

Eric300 · #4 02-16-2023, 05:18 PM

You should have BUIS on the rifle in conjunction with an optic. Just have him get used to seeing the FS in his optic. If it's a pinned-on FS, even better (than ones that attach with set screws). It's not going to hurt anything being there. With no BUIS, if your optic is rendered inoperable for some reason at least you'll have iron sights to use.

Tom S. · #5 02-16-2023, 06:02 PM

Quote:

Originally Posted by Eric300

You should have BUIS on the rifle in conjunction with an optic. Just have him get used to seeing the FS in his optic. If it's a pinned-on FS, even better (than ones that attach with set screws). It's not going to hurt anything being there. With no BUIS, if your optic is rendered inoperable for some reason at least you'll have iron sights to use.

This optical has a permanent ring and dot that can be seen even w/o illumination. It's a older Leopold sight. His planned use is short range on small game and the factory honker of a front sight just takes up too much real estate. This isn't a EOTWAWKI rifle.

ColbyBruce · #6 02-16-2023, 06:20 PM

The first photo is of a Rock River Arms gas block. The second photo shows Windham Weaponry pic rail with a bayonet lug on the left and one in the middle without a bayonet lug.

Tom S. · #7 02-16-2023, 07:33 PM

Quote:

Originally Posted by ColbyBruce

The first photo is of a Rock River Arms gas block. The second photo shows Windham Weaponry pic rail with a bayonet lug on the left and one in the middle without a bayonet lug.

Thanks - I'll look into those!

Eric300 · #8 02-16-2023, 10:01 PM

Quote:

Originally Posted by Tom S.

This optical has a permanent ring and dot that can be seen even w/o illumination. It's a older Leopold sight. His planned use is short range on small game and the factory honker of a front sight just takes up too much real estate. This isn't a EOTWAWKI rifle.

Alrighty then, how about something like a Yankee Hill folding front sight/gas block? The sight post will fold down and be mostly out of the FOV. Plus, it has a sling swivel attached.

Tom S. · #9 02-17-2023, 05:09 AM

Quote:

Originally Posted by Eric300

Alrighty then, how about something like a Yankee Hill folding front sight/gas block? The sight post will fold down and be mostly out of the FOV. Plus, it has a sling swivel attached.

Well shoot - everyone is showing it discontinued.

Fishinfool · #10 02-17-2023, 06:01 AM

Tom - Pisgah's idea about trimming the front sight post is a good one. Easy to do with a hacksaw and a file or Dremel tool to smooth and contour. Touch up with cold blue.

It looks good, lets you maintain the delta forend system, front swivel, and saves the expense and hassle of changing gas blocks.

Most low profile gas blocks I have seen are designed for free floating forends, and do not have swivels. And that is the other option - a low profile block with a free float forend, and a swivel system that attaches to the forend via rail / M lock.

Maybe more expense and hassle than the owner wants for a informal small game rifle?

For what its worth, I have an AR with a red dot and the standard triangle front sight / gas block. You can see the front sight when aiming, but it does not block the target, or overwhelm the red dot. Similar to a red dot on a handgun with co-witness irons. I think it works OK as is, but I know some like a clear sight picture, so that's a personal preference.

Larry

Tom S. · #11 02-17-2023, 07:30 AM

Quote:

Originally Posted by Fishinfool

Tom - Pisgah's idea about trimming the front sight post is a good one. Easy to do with a hacksaw and a file or Dremel tool to smooth and contour. Touch up with cold blue.

It looks good, lets you maintain the delta forend system, front swivel, and saves the expense and hassle of changing gas blocks.

Most low profile gas blocks I have seen are designed for free floating forends, and do not have swivels. And that is the other option - a low profile block with a free float forend, and a swivel system that attaches to the forend via rail / M lock.

Maybe more expense and hassle than the owner wants for a informal small game rifle?

For what its worth, I have an AR with a red dot and the standard triangle front sight / gas block. You can see the front sight when aiming, but it does not block the target, or overwhelm the red dot. Similar to a red dot on a handgun with co-witness irons. I think it works OK as is, but I know some like a clear sight picture, so that's a personal preference.

Larry

If it was my gun, I would go that route, given what I've seen and read so far. I have access to saws and a mill so lopping it off wouldn't be a problem. I'll talk to my friend and see what he says.

bamashooter · #12 02-17-2023, 09:06 AM

There are multiple options like swapping barrels, "shaving" the FSB, etc. Cutting the base is no big deal if desiring to maintain the factory GB. Any option will require a level of knowledge and skills along with necessary tools. Here's examples of shaving the FSB:

cut off front sight ar-15 - Google Search