How Many Different Size FSBs Are These?

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[ARCHIVED THREAD] - How Many Different Size FSBs Are These?

Posted: 2/2/2006 11:06:06 PM EDT

for the width of barrels?

Hmmm, i think that make sense.

Posted: 2/3/2006 4:04:36 AM EDT

[#1]

Believe your referring to the "diameter" there A96.

Most common diameters are 0.750" & 0.936" and can be had in many versions, see here: www.brownells.com/aspx/NS/store/catsearch.aspx?k=AR15+gas+block&ps=10&si=True

Mike

Posted: 2/3/2006 12:43:51 PM EDT

[#2]

Don't forget .625".

Posted: 2/3/2006 4:17:02 PM EDT

[#3]

Or .875

Posted: 2/3/2006 11:28:26 PM EDT

[#4]

Quoted:
Or .875

Please reference a photo or a source of 0.875" FRONT SIGHT BASES.
I'm well aware of the barrels and gas blocks, but I am not aware of actual front sight bases in this size.
Call me nit-picky if you will, but I believe the original question concerns front sight base ID's and not barrel diameters or gas block ID's.

Also, in relation to FSB sizes, one could argue that A1/A2 and "F" having different heights makes them different as well.

Posted: 2/4/2006 6:10:26 AM EDT

[#5]

think the beowulf .50 is an oddball.

Posted: 2/4/2006 9:50:50 AM EDT

[#6]

Quoted:
think the beowulf .50 is an oddball.

That's right, I heard that once too.
Something like 0.905" or 0.907"
Obviously, 0.875" was too small and 0.936" was too big

Wait, or maybe they just wanted to build a non-standard barrel so you can ONLY buy gas blocks from them?

Posted: 2/4/2006 11:14:55 AM EDT

[#7]

Quoted:
Quoted:
think the beowulf .50 is an oddball.

That's right, I heard that once too.
Something like 0.905" or 0.907"
Obviously, 0.875" was too small and 0.936" was too big
Wait, or maybe they just wanted to build a non-standard barrel so you can ONLY buy gas blocks from them?

isnt that how you do it?

Posted: 2/4/2006 11:17:36 AM EDT

[#8]

Compass Lake has an oddball setup, but it's not a FSB, really, just a gas block. I have one of their gas blocks. Some tird on ebay sold it to me as a bull barrel gas block, but guess what, it wasn't. I got it cheap enough so that I didn't pursue resolution and someday I'll by an RRA bull barrel and reprofile it so that I can use this gas block.

Link

Link - first gas block on the page.

Posted: 2/4/2006 11:43:12 AM EDT

[#9]

Quoted:
Wait, or maybe they just wanted to build a non-standard barrel so you can ONLY buy gas blocks from them?

isnt that how you do it?

Not ME, that's how THEY do it.
I make barrels to fit whatever parts the customer wants.
Sometimes that means really weird/cool setups like a 300x221 SBR barrel with a pistol located 0.936" gas block to hide under a rifle length handguard.
Then the barrel steps down to around 0.700" to save on weight out to the muzzle.
At the muzzle, there is a 0.920" shoulder to properly supprt a suppressor for 5/8-24 threads.
That's just a wacky looking barrel, but it's that way for a REASON.
I see no reason for an odd sized gas block when there are several standards available.

Posted: 2/4/2006 11:44:28 AM EDT

[#10]

Quoted:
Compass Lake has an oddball setup, but it's not a FSB, really, just a gas block.

What's the inside diameter of that CLE gas block?

Posted: 2/4/2006 12:57:42 PM EDT

[#11]

Quoted:
Quoted:
Compass Lake has an oddball setup, but it's not a FSB, really, just a gas block.

What's the inside diameter of that CLE gas block?

MSTN has one on his page in the Industry section (on a Super-SAM) and says it's .850" ID.

Posted: 2/4/2006 1:52:10 PM EDT

[#12]

Quoted:
Quoted:
Quoted:
Compass Lake has an oddball setup, but it's not a FSB, really, just a gas block.

What's the inside diameter of that CLE gas block?

MSTN has one on his page in the Industry section (on a Super-SAM) and says it's .850" ID.

Ya, 0.850 sounds right. It's in one of my boxes of "stuff" (read junk). I might get to that project in the next millenium. The MSTN rifle was the motivating factor, BTW.

Posted: 2/4/2006 3:28:25 PM EDT

[#13]

Quoted:
Ya, 0.850 sounds right.

Geesh, a whole 0.025" different from Armalite's standard.
I would chuck it up and open it to 0.875"
Should you ever want a different gas block, there is always Armalite and LaRue options as well then.
Having a special barrel diameter at the gas block seat gets you nowhere.

Posted: 2/4/2006 9:33:24 PM EDT

[#14]

I swiped ths from the Larue website:

LT202-1: LaRue Low Profile Gas Block - 0.75" AR15
LT202-2: LaRue Low Profile Gas Block - 0.625" AR15
LT202-3: LaRue Low Profile Gas Block - 0.875", 0.275" Spacing, AR10
LT202-5: LaRue Low Profile Gas Block - 0.875", 0.3" Spacing, AR10

Does that mean they don't have a 0.875" for the AR15?

The missing LT202-4 perhaps?

Posted: 2/4/2006 9:57:08 PM EDT

[#15]

Quoted:
Does that mean they don't have a 0.875" for the AR15?

There are no 0.875" diameter gas block seat AR-15 barrels unless you had one custom made from someone like me.

Posted: 2/4/2006 11:25:11 PM EDT

[#16]

What diameter gas blocks do guys use who have Bull barrels? They must be greater than 0.750"

I too was inspired by MSTN's "Super Sam" and was going to have a custom barrel made. Getting a good gas block for it is the sticking point and I was looking at the CLE one; now I know it's not a dimension commonly in use I'm not so sure.

I have a Larue low-profile on my Recce and was hoping for a bigger brother on a bull barrel. With these set-screw type gas blocks I like to go with an extended handguard which covers them to prevent them from being knocked askew.

Posted: 2/4/2006 11:30:36 PM EDT

[#17]

Quoted:
What diameter gas blocks do guys use who have Bull barrels? They must be greater than 0.750"

Traditionally, bull barrels are 0.936" at the gas block seat.
LaRue does not offer a block that big, so 0.875" is your best bet if you want a LaRue gas block.
It's gonna be a custom barrel proposition for sure, but a regular bull barrel could also be re-profiled to get where you want to be.

Posted: 2/5/2006 7:06:52 AM EDT

[#18]

Can the Larue 0.875" gas block be refitted to work on an AR15 barrel?

I'm not big on Tradition. All my ARs have either Green or Flat Dark Earth furniture. I plan on having my "bull" barrel made to be 22" long instead of the traditional 20" or 24".

Posted: 2/5/2006 7:19:58 AM EDT

[#19]

Quoted:
Can the Larue 0.875" gas block be refitted to work on an AR15 barrel?

It should not be too much trouble to bore out a 0.875" block to 0.936" if that's what you are asking.
If you want an 0.875" bull barrel, that's even easier.

Posted: 2/5/2006 12:03:30 PM EDT

[#20]

what's the standard size for "M4" type barrels? What size is it for "light weight/pencil" barrels?

Posted: 2/5/2006 12:19:45 PM EDT

[#21]

Quoted:
what's the standard size for "M4" type barrels? What size is it for "light weight/pencil" barrels?

Gas block sizing:

Pencil and true lightweights: 0.625"
Most HBARs, medium weights, govt profiles, M4's, AR-10A2/A4 etc: 0.750"
AR-10T: 0.875"
Most bulls: 0.936"

Posted: 2/5/2006 9:39:59 PM EDT

[#22]

Quoted:
Quoted:
what's the standard size for "M4" type barrels? What size is it for "light weight/pencil" barrels?

Gas block sizing:

Pencil and true lightweights: 0.625"
Most HBARs, medium weights, govt profiles, M4's, AR-10A2/A4 etc: 0.750"
AR-10T: 0.875"
Most bulls: 0.936"

Is there a place to buy a .625" FSB?