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3/27/2012 5:28:54 PM EDT
I currently have a S&W M&P 15. Looking to put on a Midwest 12" once piece free float rail. What size gas block do I get? A .750? I was looking to get a Midwest industries low profile block.
Also, are there better gas blocks to consider? thanks ...

Here's my current setup.

http://i944.photobucket.com/albums/ad281/RYANGEE_photos/photo1.jpg
http://i944.photobucket.com/albums/ad281/RYANGEE_photos/photo2.jpg
3/27/2012 5:30:09 PM EDT
[#1]
seven five zero
3/27/2012 5:31:09 PM EDT
[#2]
thanks!
3/27/2012 7:41:18 PM EDT
[#3]
Without an educated eyeball or caliper here is the ghetto method.

Looking at vendor's sites you probably knew that what you had was either .750" or .625"
Whip out the hillbilly caliper (adjustable wrench) and adjust it to the exposed barrel section
that is in the center of the FSB.

If the open jaws measure  5/8" =.625"
_____________________ 3/4" = .750"

With closer dimensions the hillbilly method is much too crude, but here we have an 1/8" difference
which is enough of a difference.

Basic, electronic calipers are cheap.
Here's the Chicom caliper that gets re-labeled by many brands....
VXB caliper

3/27/2012 7:57:46 PM EDT
[#4]
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!
3/27/2012 8:02:32 PM EDT
[#5]
consider a hand guard with cut out for fsb
3/27/2012 8:12:16 PM EDT
[#6]
Quoted:
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!


This. You'd be better off trimming down your FSB to work under the rail you want.
3/27/2012 8:30:53 PM EDT
[#7]
Quoted:
Quoted:
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!

This. You'd be better off trimming down your FSB to work under the rail you want.

Assuming you never want to go back to the current configuration.

A clamp on type block under a handguard will never go anywhere, it's completely shielded so its "strength" is pretty irrelevant.

I would not recommend a set screw type gas block for use with a barrel with taper pin scars, it's not secure when used on one of those barrels.
3/27/2012 8:33:56 PM EDT
[#8]
Quoted:
Quoted:
Quoted:
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!

This. You'd be better off trimming down your FSB to work under the rail you want.

Assuming you never want to go back to the current configuration.

A clamp on type block under a handguard will never go anywhere, it's completely shielded so its "strength" is pretty irrelevant.

I would not recommend a set screw type gas block for use with a barrel with taper pin scars, it's not secure when used on one of those barrels.


I figured this was obvious, but yes.
3/27/2012 8:36:49 PM EDT
[#9]
Quoted:
Quoted:
Quoted:
Quoted:
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!

This. You'd be better off trimming down your FSB to work under the rail you want.

Assuming you never want to go back to the current configuration.

A clamp on type block under a handguard will never go anywhere, it's completely shielded so its "strength" is pretty irrelevant.

I would not recommend a set screw type gas block for use with a barrel with taper pin scars, it's not secure when used on one of those barrels.

I figured this was obvious, but yes.

Many don't understand that you can't just buy another pinned type front sight base to replace the altered one, so it bears repeating.
3/27/2012 8:37:04 PM EDT
[#10]
Quoted:
Quoted:
Without an educated eyeball or caliper here is the ghetto method.

Looking at vendor's sites you probably knew that what you had was either .750" or .625"
Whip out the hillbilly caliper (adjustable wrench) and adjust it to the exposed barrel section
that is in the center of the FSB.

If the open jaws measure  5/8" =.625"
_____________________ 3/4" = .750"

With closer dimensions the hillbilly method is much too crude, but here we have an 1/8" difference
which is enough of a difference.

Basic, electronic calipers are cheap.
Here's the Chicom caliper that gets re-labeled by many brands....
VXB caliper



wow err u could look at it and say oh its a gov profile it's 750
consider a hand guard with cut out for fsb

That would be the educated eyeball thing.
For someone not familiar with the platform, gov't profile may not be understood.
3/27/2012 8:41:43 PM EDT
[#11]
sorry everyone should have calipers anyway
3/27/2012 8:47:02 PM EDT
[#12]
Quoted:
I can't understand why you would want to remove a perfectly pinned, strong as all hell front sight and replace it with some set screw add on!

I know, I'm a fan of the iconic A-frame as well.
Having said that, removing it intact and safing it away allows the user to go back. (the barrel and FSB being a unique set)

As mentioned above there are some extended rails that have cut-outs that allow the FSB to remain.
Centurion
3/27/2012 8:55:42 PM EDT
[#13]
Quoted:
sorry everyone should have calipers anyway

If it's not in the kitchen junk drawer some will not have one....
There might be a 6" Crescent in there though.


3/27/2012 9:27:55 PM EDT
[#14]
i get out the tape measure and hold her up there and close one eye make a real funny face when i do it too.
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