URGI and Gas Port Diameter of BCM 16" Midlength?

**CajunCourier** · 09-10-19, 22:02

I'm a knuckle hair away from ordering a Geissele URGI Near Clone upper to join my other middies. It's between that and a BCM. Anyone know for certain what gas port diameter current production BCM midlength barrels are? I assume its .076", but Garand Thumb's video on the URG-I claimed that the .076" DD barrel is overgassed compared to a BCM because USASOC wanted the extra gas for reliability.

Also, for those who have a URGI, how does it run? Geissele says it's optimized for the higher pressures of M855A1 and suppressed use. How does it do with M193/M855 and .223 unsuppressed?

**JediGuy** · 09-11-19, 07:37

I don’t know the answer to your questions, but logically, I’m not sure that it makes sense to enlarge a gas port to run with higher pressure ammunition.

If true, this would suggest that BCM’s gas ports are actually undersized, if an enlargement was required for reliability.

This is all conjecture, and I would note that BCM’s location is a couple degrees of latitude north of me, so I would expect they run their guns in subzero weather for testing.

**mack7.62** · 09-11-19, 09:58

Why do you want to compare a 14.5 mid to a 16 mid?

**tehpwnag3** · 09-11-19, 10:04

Usually, an "optimization" for hot ammo plus suppressor is to shrink the GP size.

**CajunCourier** · 09-11-19, 10:12

Originally Posted by mack7.62

Why do you want to compare a 14.5 mid to a 16 mid?

Because I figure 16” mid with the slightly longer dwell time might have an advantage.

**Clint** · 09-11-19, 10:47

Our view is MID is shorter than Optimum for a 16" barrel.

Have a look at our BRT OPTIMUM barrels and uppers.

The 14.5" MPC uses a MID gas system, while the 16" MPR uses the longer EXT gas system.

Both run nicely on a wide variety of quality ammo.

Originally Posted by CajunCourier

Because I figure 16” mid with the slightly longer dwell time might have an advantage.