Sons of Liberty Armorers Class - AAR
- Thread starter pangris
- Start date
Riflespeed has:
Mechanical advantage
12 adjustment points to dial-in the optimum setting
Great design
Downside:
Space management, especially those who want to locate the suppressor up close to the handguard with a tiny gap of clearance.
Interesting to learn about the "Edgewater Spring Guide" I never knew about that. Thank you for sharing.The original production Colt Model 601 rifles had a larger gas port and an Edgewater Spring Guide, not the buffer we know today.
The original 55gr 5.56x45mm ammunition was loaded with tiny stick propellant, one of which I think was IMR 8208M (precursor to our modern IMR 8208XBR), and those rifles ran beautifully with very clean bore and gas systems. DoD could not get the round counts they were demanding that would pass the MAP, MPLM, and MPSM specs using the tiny stick powders, so surplus ball propellant with lower flame temperature (WC 846) was substituted without consulting the rifle designers. It’s also a slower-burning ball propellant, so the burn curve got extended with higher pressure down-bore.
That raised port pressure 10,000-20,000psi and caused the cyclic rate to depart from the acceptable window of operation. Changes made to the AR-15 subsequent production models and XM16E1 band-aid uppers was to reduce the gas port diameter and replace the Edgewater Spring Guide with the rifle buffer we still have today.
Those changes were standardized with the Colt 603 M16A1 and 604 (USAF M16 with no Forward Assist), in addition to chromed bores and chambers, parkerized BCG with chrome bolt bore in the carrier (replaced fully hard-chromed BCGs), forged FSBs, stronger furniture with more glass fill in the phenolic resin plus a cleaning kit compartment, birdcage FH, fully-fenced lower receiver around the mag release button, Forward Assist, and tighter controls placed on parts manufacturing with the updated TDP.
But they had to spec the rifle around that new ball propellant ammunition, which is often overlooked by those who like to dive into the details of all the other outward-appearance parts.
