Pin Gage Set to Measure GPs

[M Sadler]

Is there a reasonable option for a set like this in the sizes needed to measure gas ports? All I see are massive sets with 90% of the set too small or big for this application. Doesn’t someone make one just for this application? Any ideas or advice? Thanks!

You have too much time on your hands. What exactly do you plan to do with the trove of information you collect? If this is something you just have to do, run with @MarkM's suggestion.

[OldState]

You have too much time on your hands. What exactly do you plan to do with the trove of information you collect? If this is something you just have to do, run with @MarkM's suggestion.

Are you serious?? Maybe you would be better off posting on TOS.

Im trying to tune a 50/50 suppressed 11.5” rifle and would like to establish a point of reference to determine the best path to proceed. It has a barrel that is supposed to have a .070 GP but it shoots like its much bigger.

[WS6]

Are you serious?? Maybe you would be better off posting on TOS.

Im trying to tune a 50/50 suppressed 11.5” rifle and would like to establish a point of reference to determine the best path to proceed. It has a barrel that is supposed to have a .070 GP but it shoots like its much bigger.

Port profile in the barrel matters, and pin gauges won't show this. If its eroded out, it's flowing a lot more than the oriface you can gauge on the barrel's OD would otherwise indicate.

[OldState]

Port profile in the barrel matters, and pin gauges won't show this. If its eroded out, it's flowing a lot more than the oriface you can gauge on the barrel's OD would otherwise indicate.

It’s a brand new barrel. Colt FBI heavy 11.5”. Its ejecting xm193 at 1 o’clock with enough force to ding the side of the case on the brass deflector. This is with a H2 buffer. Recoil with that ammo is pronounced. That’s WITHOUT a suppressor. Fiocchi .223 and Brown Bear feel “normal” and eject at 3:30-4.

I’m considering a BRT reduced gas tube but would like to know where I’m at now as it’s supposed to be .069-.070. If the port truly is that size then I will have to decide which direction to go. I prefer to fix this from the gas end rather than with buffers and springs.

I plan on building a couple more rifles before the election season kicks off and could use a pin gauge set. I’m just not spending $50 for a big set when I’m only going to used a few pins.

[P2Vaircrewman]

Wire gauge drill bits, individually or sets. Use one end as a gauge and the other to drill or enlarge a hole.

https://www.mcmaster.com/number-jobbers'-drill-bits

[OldState]

Wire gauge drill bits, individually or sets. Use one end as a gauge and the other to drill or enlarge a hole.

https://www.mcmaster.com/number-jobbers'-drill-bits

For some reason I feel like I looked for these but I must have missed them. Thanks! Interesting that there are drill sizes that almost perfectly line up with popular GP sizes

[titsonritz]

What did you mean by “first three lines”?

The first three rows in the are the smallest pins and are appropriate for measuring gas ports.

[P2Vaircrewman]

Generally where possible standard tooling sizes are used in most manufacturing. I would be surprised barrel makers used custom drills for gas ports considering the increments between drill sizes is usually .003".

[Clint]

PM your address and I'll send a couple old drill bits you can use to verify the size on this thing.

It’s a brand new barrel. Colt FBI heavy 11.5”. Its ejecting xm193 at 1 o’clock with enough force to ding the side of the case on the brass deflector. This is with a H2 buffer. Recoil with that ammo is pronounced. That’s WITHOUT a suppressor. Fiocchi .223 and Brown Bear feel “normal” and eject at 3:30-4.

I’m considering a BRT reduced gas tube but would like to know where I’m at now as it’s supposed to be .069-.070. If the port truly is that size then I will have to decide which direction to go. I prefer to fix this from the gas end rather than with buffers and springs.

I plan on building a couple more rifles before the election season kicks off and could use a pin gauge set. I’m just not spending $50 for a big set when I’m only going to used a few pins.

[WS6]

Everyone knows you can buy pin gauges on Amazon for $2-7/ea, right?