I'm wanting to build my own gas block for a .750 barrel.

Would anyone happen to know what the nominal distance is from the center of the barrel hole to the center of the gas hole is?

I've got an A2 front site I'm wanting to ditch and make a picatinny-style gas block.  Since I've got a CNC machine shop, I can't see spending the money they're asking on those things, for no more than what's in them.

If anyone knows off the top of their head, or perhaps has a link to a drawing that shows that detail, I'd greatly appreciate it.

I have that info at home, I'll get back to you tonight.  Are you asking about the distance from the gas port hole in the barrel to the corresponding hole in the gas block, from the step up in the barrel I presume?  I can tell you the hole in the gas block is a good deal larger than the one in the barrel.

I have a similar question. What is the distance from center of bore to the gas tube hole in the upper?

buckmeister

Sorry, I was really busy last night, I'll get the info tonight.

Quoted: I have a similar question. What is the distance from center of bore to the gas tube hole in the upper? buckmeister

That's a tough one to measure because that distance may not be exact from upper to upper, there is some tolerance there since the gas tube is not affixed to the upper.  However the distance from the center of the gas bore on the gas block to the step up in the barrel is .3251.  As a general rule, on a carbine length system you would add 7 inches to that so a good rough estimate would be 7.3251.  Besides you would not want to measure from the upper receiver to the barrel to determine the distance when designing a gas block, you would want to use something on the barrel as a reference point like the step up behind the hand guard cap.  Also take into account the gas hole on the barrel is much smaller and is not totally centered longitudinally on the gas hole in the gas block.

Quoted: I'm wanting to build my own gas block for a .750 barrel. Would anyone happen to know what the nominal distance is from the center of the barrel hole to the center of the gas hole is? I've got an A2 front site I'm wanting to ditch and make a picatinny-style gas block.  Since I've got a CNC machine shop, I can't see spending the money they're asking on those things, for no more than what's in them. If anyone knows off the top of their head, or perhaps has a link to a drawing that shows that detail, I'd greatly appreciate it.

I'm not sure what to points you are trying to measure between, I assume by barrel hole you mean the gas port in the barrel, but I'm not sure what you mean by gas hole.

I'm looking for the center to center distance between the .750 hole that slides over the barrel and the hole that the gas tube goes in.

In other words, if I was to bore a hole through a piece of aluminum at .750, how far would I have to move the milling machine to spot drill the hole for the gas tube?

Sorry for taking so long to respond, but I'm in the middle of moving my house.......Kinda limits my internet time right now.