Use barrel until significant accuracy degradation develops.
The main take aways from this barrel –
- This barrel was from a batch of the first 12.5″ mid length gas barrels we ever produced from around 8 years ago.
- This barrel had a harsh firing schedule along with non existence maintenance and general upkeep regiment.
- The barrel is still capable of producing impacts at 600 yards on ⅓ silhouette humanoid target yards using 77 gr ammo, the barrel is not able to stabilize 55 gr ammo anymore because of the smaller bearing surface of that bullet combined with the bore erosion.
- Gas port erosion was significantly less than what we anticipated, we’ve seen other barrels with a comparable firing schedule with significantly more erosion, gas port only grew by .003″.
This is what we refer to as a “farm” build, which basically means it has been through hell cosmetically and mechanically. Round count for this barrel exceeds 20,000 rounds, SilencerCo saker silencer attached for the entire duration. Steel cased, cheap ammo, expensive ammo, hot ammo, etc, full auto use and mag dumps were frequent. It had never had a patch pushed down the bore, it received an occasional cleaning via pressure washer once in a blue moon after falling off ATVs into mud pits etc.
Bore was cleaned with Lucas gun cleaner- 6x wet patches followed by 3x dry to reveal bore surface. Note that is was surprisingly easy to clean with no excessive copper or carbon fouling. We attribute this to our barrel manufacturing and finishing process.
New/ freshly rifled Specs-
Note- The original bore and groove measurements were not recorded, the following measurements are what we generally hold our specs to for 5.56×45 NATO 1:7 twist.
- Minimum bore- .2190″
- Minimum groove .2247″
Gas Port- .086″
Current measurements after disassembly and cleaning
Gas Port- .089″
- Chamber end bore- .2243″
- Mid barrel bore- .2246″
- Muzzle end bore- .2230+
- Groove- .2248″
Pictures showing wear and carbon buildup during disassembly process-
Carbon buildup around noveske gas block
Carbon buildup and debris- lower receiver, wear on hammer face
Carbon buildup on SilencerCo flash hider/suppressor mount
Carbon buildup – upper receiver
First picture after uninstalling barrel and gas block
Dirt and debris buildup on upper
Ejection port shot
SilencerCo saker wear/carbon-buildup (normal)