Here are my measurements of three different Grendel barrels, OAL to touch the lands.
BCA---------------------------------------------------------RAP---------------Monster 20
Hornady 95 V-Max 2.267 2.286 2.235 full neck 2.165
Hornady 123 Eld Match 2.298 2.330 2.289
Sierra 142 MK------ 2.367 2.330
Sierra 130 GC 2.375? 2.413 2.389
Sierra 120 MK 2.330 2.292 2.265
Sierra 120 Pro Hunter 2.280 2.261 2.242
Sierra 107 MK 2.340 2.364 2.335
Speer 140 Hot cor beyond mag len 2.303 2.297
Speer 90 TNT 2.290 (full in neck 2.190) 2.290 2.260
Speer 120 gold dot beyond 2.312 2.369 2.345
Match Monster 100 gn 2.150(full in neck 2.150) 2.320 2.270
Match Monster 123 gn beyond 2.300 2.294 2.269
Nosler 90 Varmageddon --------------------------------------------------2.340 full neck 2.270
Barnes 120 Match Burner --------------------------------------------------2.275
From my experience you need to measure the bullets in your grendel as there is a lot of differences between barrels.
The above data can help with bullet selection if you want bullets that will fit the magazine, be close to the lands and be seated fully in the neck.
Note that the Sierra 120 Pro hunter loaded for the Monster 20 barrel if seated to mag length (2.260 to 2.290) would be jammed in the lands and could be dangerous.
Safe shooting all!
BCA---------------------------------------------------------RAP---------------Monster 20
Hornady 95 V-Max 2.267 2.286 2.235 full neck 2.165
Hornady 123 Eld Match 2.298 2.330 2.289
Sierra 142 MK------ 2.367 2.330
Sierra 130 GC 2.375? 2.413 2.389
Sierra 120 MK 2.330 2.292 2.265
Sierra 120 Pro Hunter 2.280 2.261 2.242
Sierra 107 MK 2.340 2.364 2.335
Speer 140 Hot cor beyond mag len 2.303 2.297
Speer 90 TNT 2.290 (full in neck 2.190) 2.290 2.260
Speer 120 gold dot beyond 2.312 2.369 2.345
Match Monster 100 gn 2.150(full in neck 2.150) 2.320 2.270
Match Monster 123 gn beyond 2.300 2.294 2.269
Nosler 90 Varmageddon --------------------------------------------------2.340 full neck 2.270
Barnes 120 Match Burner --------------------------------------------------2.275
From my experience you need to measure the bullets in your grendel as there is a lot of differences between barrels.
The above data can help with bullet selection if you want bullets that will fit the magazine, be close to the lands and be seated fully in the neck.
Note that the Sierra 120 Pro hunter loaded for the Monster 20 barrel if seated to mag length (2.260 to 2.290) would be jammed in the lands and could be dangerous.
Safe shooting all!