05-15-2023, 04:35 PM
I also Cerakote the insides of all my upper receivers in the extension tunnel. Some I have foamed-off the carrier raceway so the carrier rails dont gall up on the Cerakote.
Im not really concerned about heating in the barrel extension area since we know what the temperature measurements are from the M4 during extreme full auto testing done by ARDEC at Rock Island.
The barrel shank area only got up to 420 deg F after a 280rd full auto set of mag dumps in compressed time.
Im not able to reach those temperature levels with any semi auto Grendel, nor would I attempt to do so on my barrels.
Grendel runs at much lower chamber pressure than 5.56 NATO and we typically dont go cyclic with 6.5 Grendel.
This is probably why I see the same accuracy today as I did when I first built my uppers. Whatever Im doing with bedding, its holding true over many years.
The sections of the barrel that seemed to accumulate the most heat in the ARDEC tests were midway on a carbine length profile before the step up, and right before the step up to the gas block journal and heavy forend, referred to TC-4 and TC-3 in the ARDEC tests. Look at pages 13 forward on that link.
Their main intent for those tests was to determine the surface temperatures between the smaller Colt Commando handguards that were common to the XM177E1/E2, GAU-5A/A, Colt 653, Colt 723, Colt 727, Colt 733, etc. and the new enlarged diameter, dual heat shield M4 handguards. They established in-depth 280rd Full Auto bare-naked barrel baseline measurements, before doing the same tests with both types of handguards.
I remember when all this was going on because there was a big deal about having real M4 handguards, vs carbine. I had carbine handguards on my personal 11.5 AR-15s, but saw the new Colt ads for the M4A1 and M4 with the fat handguards.
Ranger Regiment got Knights Armament RIS railed handguards shortly after, as did SF and NSW. The fat M4 handguards then were ridiculed and so last season.
When we got issued M4s in 1997, they were with the fat M4 dual heat shield handguards. We deployed to Panama with 2/75 November that year, and everyone in a Ranger Rifle Platoon had M4A1s with RIS, Aimpoint Comp Ms or ACOGs + Surefires and PAQ-4Cs.
The RIS was later replaced by the KAC RAS.
Im not really concerned about heating in the barrel extension area since we know what the temperature measurements are from the M4 during extreme full auto testing done by ARDEC at Rock Island.
The barrel shank area only got up to 420 deg F after a 280rd full auto set of mag dumps in compressed time.
Im not able to reach those temperature levels with any semi auto Grendel, nor would I attempt to do so on my barrels.
Grendel runs at much lower chamber pressure than 5.56 NATO and we typically dont go cyclic with 6.5 Grendel.
This is probably why I see the same accuracy today as I did when I first built my uppers. Whatever Im doing with bedding, its holding true over many years.
The sections of the barrel that seemed to accumulate the most heat in the ARDEC tests were midway on a carbine length profile before the step up, and right before the step up to the gas block journal and heavy forend, referred to TC-4 and TC-3 in the ARDEC tests. Look at pages 13 forward on that link.
Their main intent for those tests was to determine the surface temperatures between the smaller Colt Commando handguards that were common to the XM177E1/E2, GAU-5A/A, Colt 653, Colt 723, Colt 727, Colt 733, etc. and the new enlarged diameter, dual heat shield M4 handguards. They established in-depth 280rd Full Auto bare-naked barrel baseline measurements, before doing the same tests with both types of handguards.
I remember when all this was going on because there was a big deal about having real M4 handguards, vs carbine. I had carbine handguards on my personal 11.5 AR-15s, but saw the new Colt ads for the M4A1 and M4 with the fat handguards.
Ranger Regiment got Knights Armament RIS railed handguards shortly after, as did SF and NSW. The fat M4 handguards then were ridiculed and so last season.
When we got issued M4s in 1997, they were with the fat M4 dual heat shield handguards. We deployed to Panama with 2/75 November that year, and everyone in a Ranger Rifle Platoon had M4A1s with RIS, Aimpoint Comp Ms or ACOGs + Surefires and PAQ-4Cs.
The RIS was later replaced by the KAC RAS.
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