2 goals:
1. No ejector smear on case head. Fix - Buffer weights
2. Brass ejection to 3:00, aka 90 deg from rifle. (Muzzle 12:00) Fix - adjustable gas block or gas port diameter.
Buffers: H-H2. Whichever to eliminate ejector smears. Buffers make for only 10% manipulation results.
Gas Block: Go standard until it's necessary to go adjustable. How to decide after STD gas block install:
- Brass ejecting forward of the ejection port, prior to 2:45, is over gassed. Fix - Adj. gas block (2 types)
- Brass ejecting rearward, past 3:30 is under gassed. Fix - drill gas port diameter larger
Over gassed situation:
Option 1 - Restrictive style adjustable gas block. Most common style. "Aero Precision" has a good one. This style gas block reduces gas port diameter in barrel until only enough gas is needed to achieve 100% desired functionality. Rest of gas is vented out the barrel behind bullet.
Option 2 - Bleed off adjustable gas block. "Superlative Arms". Has both restrictive and bleed off modes. The bleed off mode works great. The restrictive mode does not. Choose this gas block if running a suppressor. The gas block bleeds off the extra gas out the gas block. Unlike the restrictive style gas block that uses extra gas to propel the bullet. Bleed off gas block will lend to less muzzle velocity. This bleed off gas block is also a last ditch effort to save a barrel with too large a gas port diameter.
Under gassed situation:
You must drill the gas port. Harbor freight has a numbered drill bit set. Use the smooth ends of the bits as a pin gauges, and the cutting ends to drill. Measure the smooth ends with a caliper. Adjust by .002" increments larger in bit size until desired functionality achieved. A dowel rod inserted into the barrel will prevent over drilling.
Notes:
A rifle with a clean receiver, properly oiled BCG, within the first 20-30rnds, will eject brass slightly forward. About 15 minutes on the "clock illustration". 100% desired functionality is a clean rifle ejecting brass to 2:45 and settling in at 3:00 ejection.
