07-08-2017, 11:15 PM
Brandi,
An 18" MLGS Grendel should be .076" port diameter. .0865-.0885" is slightly bigger, and will allow more gas volume to flow, which usually creates excessive bolt carrier speed and too early unlocking.
You can do adjustable gas at the block, or at the gas key or carrier if you go with adjustable gas.
Liberty barrels have normally been ported at .0935" for MLGS, which is way too much and needs to be tamed.
FTExtract is the main symptom you will see with an excessively large gas port at Mid-Length, because the case is still obdurated to the chamber wall, while the extractor is trying to rip it out. Since there is way more surface area on the case purchased to the wall and under pressure, versus the small area of the extractor contacting the case rim, the chamber wins that tug-o-war.
With adjustable gas, you will often have a hard time fitting it under slim MI Gen 3 handguards, so look for gas blocks that will clear the ID of that handguard. You could also just replace the carrier key with a Sun Devil adjustable key, which is a lot easier to access and service, or get an adjustable carrier from 2A, but they're pricey ($419).
The Sun Devil ADIGS is $60. http://shop.sundevilsales.com/ADIGS-Gas-...GS-KIT.htm
An 18" MLGS Grendel should be .076" port diameter. .0865-.0885" is slightly bigger, and will allow more gas volume to flow, which usually creates excessive bolt carrier speed and too early unlocking.
You can do adjustable gas at the block, or at the gas key or carrier if you go with adjustable gas.
Liberty barrels have normally been ported at .0935" for MLGS, which is way too much and needs to be tamed.
FTExtract is the main symptom you will see with an excessively large gas port at Mid-Length, because the case is still obdurated to the chamber wall, while the extractor is trying to rip it out. Since there is way more surface area on the case purchased to the wall and under pressure, versus the small area of the extractor contacting the case rim, the chamber wins that tug-o-war.
With adjustable gas, you will often have a hard time fitting it under slim MI Gen 3 handguards, so look for gas blocks that will clear the ID of that handguard. You could also just replace the carrier key with a Sun Devil adjustable key, which is a lot easier to access and service, or get an adjustable carrier from 2A, but they're pricey ($419).
The Sun Devil ADIGS is $60. http://shop.sundevilsales.com/ADIGS-Gas-...GS-KIT.htm
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com