How do you know the gas port size -vs- barrel dia.?

[DirectDrive]

The problem with using the drill bit and caliper method is drill bits are not made in .001" increments so it will only get you in the ballpark. One of the many uses of pin gauges is to make sure instruments like calipers and micrometers are measuring accurately. The set pictured above is too large for measuring gas ports.

Come on man, work with me.
We're not building a Mars Rover.

 

[Lennie]

The problem with using the drill bit and caliper method is drill bits are not made in .001" increments so it will only get you in the ballpark. One of the many uses of pin gauges is to make sure instruments like calipers and micrometers are measuring accurately. The set pictured above is too large for measuring gas ports.

Help me. If I have pin gauges starting at .020 through .700, I would have 500 pin gauges in my tool box. That would probably earn me the slide rule, plastic insert for my shirt pocket, nerd merit badge plus drive me over the edge of sanity.

 

[Stomper]

How many Ar15 guys does it take to answer a gas port size question?

Four, one to answer it, one to question it, one to reaffirm it with more details, and one to make sure it goes to 11.

Don't you mean.... "0.11"?

 

[titsonritz]

Yeah having tools sucks.

 

[Cannonman]

The problem with using the drill bit and caliper method is drill bits are not made in .001" increments so it will only get you in the ballpark. One of the many uses of pin gauges is to make sure instruments like calipers and micrometers are measuring accurately. The set pictured above is too large for measuring gas ports.

I just picked one, of several hundred pictured for sale, as an example of what they look like. The problem is you'll rarely use more than a few of them and then on rare occasions. If you would like, PM me and I'll send you what an appropriate set of Starrett pin gauges looks like the amazing cost for a tool of such low use. I could show a drill bit and just let you imagine it's the one to fit a gas port. As far as ball park, the adjustable blocks are a set screw. No 0.001 increments. Hence, not needed.

 

[powermad]

One of the many uses of pin gauges is to make sure instruments like calipers and micrometers are measuring accurately. The set pictured above is too large for measuring gas ports.

I use the standards supplied with my micrometers to check the accuracy.
.250" dia, 1" - 6" long pins.
I use those to check calipers also.

You don't have to buy an entire set of class ZZ pins, just the ones in the range you may encounter if you want to get a precise measurement. Probably $25 or so for quality ones.
You could nerd out all the way and get the nifty pin handle so body temp doesn't affect the reading, just to be on the safe side.

 

[theduke]

If you have a stack of 3 drill bit/pin boxs

abc
123
and regular " system
You pretty much cover most all the sizes.

Whens that Mars rover leaving town......?>

 

[Cannonman]

I use the standards supplied with my micrometers to check the accuracy.
.250" dia, 1" - 6" long pins.
I use those to check calipers also.

You don't have to buy an entire set of class ZZ pins, just the ones in the range you may encounter if you want to get a precise measurement. Probably $25 or so for quality ones.
You could nerd out all the way and get the nifty pin handle so body temp doesn't affect the reading, just to be on the safe side.

"Word!"

If you have a stack of 3 drill bit/pin boxs

abc
123
and regular " system
You pretty much cover most all the sizes.

Whens that Mars rover leaving town......?>

Short, sweet, realistic, common sense. I'm not sure if C-19 has stopped ticket sale on the rover. Hope not. I'd like a nice get-away. Ya know with your grounding and summation, it seems to me that the port size is really irrelevant. Other than tap it if it seems too small, its the block that becomes the issue. And with the block there's nothing you can do except order an adjustable one. Now there's all these pages of comments that got here by me not asking the appropriate question. It is and has been an enjoyable read and now I know a whole lot more about those little holes. So.... Why all the different size holes? What drives the thinking of the manufactures to put whatever size hole they use? Limiting the idea to AR formats. Either way. You guys rule and I can not thank you all enough for the education.